MALAYSIAN JOURNAL OF MICROBIOLOGY
Aim: Urinary Tract Infection (UTI) is one of the common infections in clinical practice. Increasing incidence of Multi Drug Resistant (MDR) uropathogens limited the therapeutic options; thereby prompted the interest in old drugs like Fosphomycin. The current study was undertaken for the comparative evaluation of vitro activity of Fosphomycin and Nitrofurantoin against ESBL producing and carbapenem resistant uropathogens. We also tried to compare the coexistence of resistance of both the drugs with another commonly used oral drug for UTI, i.e. Flouroquinolone.
Methodology and Results: A total 101 MDR uropathogens were tested for ESBL production, carbapenem resistance, Fosphomycin susceptibility and Nitrofurantoin susceptibility as per the CLSI guidelines. Fosphomycin susceptibility testing was carried out by disc diffusion test. Klebsiella pneumoniae was the commonest MDR uropathogen followed by Pseudomonas aeruginosa and Escherichia coli. Susceptibility to Fosphomycin among the ESBL producer and carbapenem resistant uropathogen was found uniformly higher (91.8%, 90.1%) in comparison to Nitrofurantion (27.5%, 21.3%). Coexistence of resistance to Fosphomycin was much less than Nitrofurantoin in presence of resistance to Flouroquinolone.
Conclusion, Significance and impact of the study: Fosphomycin showed excellent in vitro susceptibility against both ESBL producing and carbapenem resistant MDR uropathogens. Fosphomycin has excellent in vitro action of Fosphomycin against ESBL producing and carbapenem resistance uropathogen in comparison to Nitrofurantoin, hence will be useful for the treatment of drug resistsant uropathogens.
Keywords: Urinary tract infection, ESBL producer, carbapenem resistance, Fosphomycin, Nitrofurantoin.
Aims: Milk is rich of nutrients that are necessary for the growth of various microorganisms. The aim of the present study was to evaluate the microbial quantity and quality of the raw cow’s milk sold through street trading in Meknes, Morocco, and to study the variation and seasonal relationship of microbial diversity during the four seasons of the year.
Methodology and results: Raw cow’s milk samples were collected randomly between May 2015 and April 2016 from 3 street trading sale points, two popular neighborhoods (station 1 and station 2) and one popular market, and they were analyzed microbiologically. The results showed that the contamination rates of Total Plate Count, Total Coliforms, Fecal Coliforms, Lactobacilli, Lactococci and Yeasts and Molds were 8.8×108 CFU/mL, 8.9×105 CFU/mL, 2×103 CFU/mL, 4.6×108 CFU/mL, 7.5×108 CFU/mL and 4.1×103 CFU/mL, respectively. Moreover, Escherichia coli, Staphylococcus aureus, Clostridium perfringens and Listeria monocytogenes were detected in 66.67% (24/36), 75% (27/36), 36.1% (13/36) and 19.44% (7/36), respectively, while Salmonella was not detected in this study.
Conclusion, significance and impact of study: The highest microbiological count in raw milk samples was found in summer, while the lowest was detected in winter (p˂0.005). Therefore, the quality of milk marketed in Meknes region of Morocco is deteriorated due to the lack of good hygienic conditions of raw cow’s milk sold through street trading.
Keywords: Raw cow’s milk, street trading, microbiological quality, season
Aims: A simple in vitro model system was applied in this study assessing the dynamics of the microbial community associated with the shrimp gut system to understand the changes that influence dietary variables.
Methodology and results: The diversity and abundance of microbiome were monitored within two different treatment slurries inoculated with shrimp faecal samples as to mimic the effect of diet manipulation, and 16S rRNA gene of MiSeq Illumina-based sequencing was applied. The different diets tested were a commercial standard diet and a prodigiosin added diet. There was very clear separation between the commercial standard diet and prodigiosin added diet as revealed by the total viable counts (TVC) and sequencing data. It suggested that the microbial community of the shrimp gut system exhibited a dynamic response with the treatments and allochthonous bacterial present. The prodigiosin added diet was clearly separated from the commercial standard diet serving as a potential shrimp feed additive. The sequencing data analysis showed that members of the genera Vibrio, Shigella and Photobacterium became predominant on the commercial standard diet treatment. The prodigiosin-added diet treatments indicated an abundance of members of the genera Micrococcus, Arthrobacter, and Shigella.
Conclusion, significance and impact of study: In vitro model system-based testing of diets could be a useful method to determine the potential effect of diet manipulation on shrimp gut system microbiome members.
Keywords: Gut bacteria, microbial community, in vitro model system, 16S rRNA gene, prodigiosin.
Aims: Bacterial biofilms can be defined as a community of microorganisms in which cells adhere to one another on a surface and are embedded in a protective matrix of lipids, nucleic acids, proteins and polysaccharides. Biofilm produced by Vibrio cholerae represents a significant threat to food safety, as they can lead to the transmission of diseases. Hence, the purpose of this study is to review the effect of different types of sodium chloride on minimum biofilm eradication concentration (MBEC) and morphology of biofilm formation of Vibrio cholerae. Methodology and results: In this study, V. cholerae biofilm was treated with four different types of sodium chloride; ‘Bario’ salt, ‘Bakelalan’ salt, commercial sodium chloride and laboratory sodium chloride. By using MBEC test, the concentration of sodium chloride needed to eradicate the biofilm of V. cholerae was determined. Based on the result obtained, commercial sodium chloride and laboratory sodium chloride showed the highest anti-biofilm activity against the biofilm of V. cholerae at 500 mg/mL concentration while no complete eradication of V. cholerae biofilm was achieved when treated with Sarawak local salts (‘Bario’ salt and ‘Bakelalan’ salt). However, noticeable inhibitions of bacterial growth were seen at the highest concentration of local salts. Conclusion, significance and impact of study: Commercial sodium chloride and laboratory sodium chloride showed a better anti-biofilm activity towards the V. cholerae biofilm formation as compared to the local salts. Thus, commercial sodium chloride and laboratory sodium chloride can be an effective anti-biofilm agent to mitigate the biofilm formation of V. cholerae. Further studies can be done to determine the MBEC values of other pathogenic bacteria against commercial and laboratory sodium chloride.
Keywords: Bacterial biofilms, sodium chloride, minimum biofilm eradication concentration (MBEC), anti-biofilm, industrial process
Aim: Klebsiella pneumoniae is considered to be one of the most frequent bacterial species associated with urinary tract infections (UTIs) and recurrent UTIs (RUTIs) worldwide. The present study aimed to comprehensively characterize K. pneumoniae isolates from women suffering from UTI and RUTIs.
Methodology and results: A total of 15 clinical isolates, collected from different hospitals in Bangladesh, were tested for biochemical features, and amplified by PCR. Antibiogram assay was performed by disk-diffusion assay. Phylogenetic and functional features were analyzed using bioinformatics platform. XLSTAT was used for principal component analysis (PCR). PCR amplification using Klebsiella hemolysin gene (khe) confirmed the presence of K. pneumoniae in agarose gel with expected product size of 486 kb. Antibiogram assay revealed all K. pneumoniae isolates to be completely resistant to six out of ten relevant drugs namely ampicillin, cephradine, chloramphenicol, erythromycin, kanamycin and sulfamethoxazole used for treating UTIs in Bangladesh. Sequencing of 16s rRNA gene of clinically significant K. pneumoniae isolates showed a high level of sequence divergence between the isolates from UTI and RUTIs as well as functional features such as SNP variants and restriction sites.
Conclusion, significance and impact of study: We surmise that the results could be used as a pipeline for further research in the identification of K. pneumoniae associated with UTI and RUTIs, and treatment of infection.
Keywords: Klebsiella pneumoniae; khe gene; PCR; 16s rRNA sequencing; phylogenetic analysis
Aims: Bifidobacteria is a non-motile, gram-positive, strictly anaerobic and non-spore-forming bacteria that can produce exopolysaccharide (EPS). EPS is a polymer of sugars, long chained polysaccharide which have been shown to give benefit towards human health. The optimum conditions for EPS production by Bifidobacterium are still scarce. Therefore, a study was conducted to optimize the growth conditions (pH, temperature and cultivation time) for a better improvement of EPS production.
Methodology and results: Three Bifidobacterium strains were cultured and the highest EPS producing strain was selected for optimization. Response Surface Methodology (RSM) was used to optimize the growth conditions for a maximum EPS production. Subsequently, EPS was characterized by using FT-IR and GC-MS. Based on the result obtained, B. pseudocatenulatum KAKii had the highest EPS production compared to the other two strains namely B. pseudocatenulatum ATCC 27919 and B. animalis. Meanwhile, the optimization of the three factors towards selected strain found that EPS produced crucially depends on time of cultivation (23.59 h) other than pH (5.0) and temperature (34.75 °C). The validation showed that the predicted and experimental values were not significantly different (P > 0.05), indicating that the developed model is fitted well for the optimization. Meanwhile, FT-IR and GC-MS results showed that the EPS was composed of D-glucose, mannose, galactose, maltose and acetic acid as by-product.
Conclusion, significance and impact of study: This result showed that the EPS produced by B. pseudocatenulatum KAKii is from hetero-exopolysaccharide group with acetic acid as by-product made them a possible anticancer agent in future.
Keywords: Exopolysaccharide, bifidobacteria, optimization, response surface methodology
Aims: The specific aim of this study was to evaluate for the first time the phytochemical constituents, functional group assignment, and antibacterial activities of the Philippine green-leafed Acalypha amentacea Roxb. (Maslakot-Ambulong), a wildcrafted medicinal plant of local traditional healers in the southern most region of Mindoro province.
Methodology and results: Aqueous leaf extracts of A. amentacea Roxb. were lyophilized and subjected to qualitative phytochemical screening and FT-IR analysis. The antibacterial activity of the plant using agar-well diffusion assay revealed highest Zone of Inhibition (ZOI) in 500 mg/mL concentration for Staphylococcus aureus (21.78 mm), Escherichia coli, (21.36 mm), Serratia marcescens (21.90 mm), Klebsiella pneumoniae (21.44 mm), and Enterococcus faecalis (20.52 mm) among other concentrations suggesting a dose dependent bioactivity. Also, compared to the antibiotic Rifampicin, A. amentacea Roxb. demonstrated better bioactivity against all the selected bacteria except S. aureus (p<0.05) and comparable to Ofloxacin when against E. faecalis. The minimum inhibitory concentration (MIC) of the extract was found to be at 15.6 mg/mL for all the bacteria except for S. marcescens with 31.25 mg/mL as MIC. The bioactivity of the plant may be accounted to the presence of alkaloid, phenol, flavonoid, tannin, and saponin which were supported by its functional groups like carboxylic acid, alcohols, amine, conjugated alkene, aromatic esters, and alkyl aryl ether.
Conclusion, significance and impact of study: The results of this investigation, proved that A. amentacea Roxb. has bioactive antibacterial principles against the selected microorganisms. This also confirms its potentiality as a new source of antibacterial agents.
Aims: Groundnut is an important food crop and is susceptible to contamination by Aspergillus. The present study was conducted to identify Aspergillus spp. from groundnuts as well as to detect mycotoxin production by toxigenic species.
Methodology and results: Molecular identification using ITS region, β-tubulin and calmodulin genes identified six species, A. niger, A. tubingensis, A. flavus, A. aculeatus, A. sydowii and A. fumigatus. Phylogenetic tree of combined sequences showed the isolates from the same species were grouped with reference strains in the same clade, thus the species identity was confirmed. Detection of mycotoxin biosynthesis genes can give an indication of mycotoxin production. Two ochratoxin A genes, PKS15KS and PKS15C-MeT were detected in seven A. niger isolates but none of the isolates produced ochratoxin A when quantification was conducted using Ultra-High Performance Liquid Chromatography. Two aflatoxin B1 biosynthesis genes, Nor-1 (norsolorinic acid) and Ver-1 (Versicolorin) genes were detected in A. flavus but only KDH7 and KL27b isolates produced aflatoxin B1 with concentrations of 1.0 μg/g and 1.1 μg/g, respectively.
Conclusion, significance and impact of the study: Various species of Aspergillus found on groundnuts may lead to potential mycotoxin contamination as toxigenic species were also recovered. The occurrence of Aspergillus spp. can reduce the quality of the legumes as well as reducing their shelf life.
Aims: The investigation aimed to examine the crude oil-contaminated soil Streptomyces flora and study their capability to grow on diesel fuel as a sole carbon source and their analysis for the presence of alkane hydroxylase gene (alkB) by PCR.
Methodology and Results: A total of 17 Streptomyces isolates were recovered from hydrocarbon-contaminated soil samples on starch casein nitrate agar medium with the ability of 4 isolates to grow on diesel [0.1 % (v/v)] as assessed by agar plate diffusion method, enzymatic assay and dry weight measurements. The ability of the four isolates (JR2b, JR3a, JR5b, and JR6f) to grow on diesel was revealed by the colour change of the reaction mixture, and showing a growth response by growing around diesel-containing wells with a percentage increase in the dry weight of 24.60, 26.23, 18.03, and 18.03 after 28 days of incubation as compared to zero time, respectively. Although the four isolates were capable to degrade diesel as indicated by the three assessment techniques they did not show any PCR product.
Conclusion, Significance and Impact of study: The isolates that grew on diesel and showed no PCR product might not contain the alkB gene, which implies that alkB gene is not the only gene that is responsible for the degradation of alkanes.
Avian influenza (AI), caused by the avian strain of influenza A virus (AIV) is one of the significant health concerns globally. Human infections with AI viruses were reported sporadically and often exhibited high mortality and morbidity rate. AI outbreaks also influenced the safety of the food supply and caused significant economic losses. Immediate control measures are required during AI outbreaks in poultry to prevent further viruses spreading. Hence, accurate, sensitive, and rapid detection methods are pivotal for decision making. Traditional methods of detection, such as virus isolation in embryonated chicken eggs, immuno-based methods, and nucleic acid amplification method, pose different limitations. These always grab the attention of researchers to improve existing methods or invent novel diagnostic approaches to compensate for the shortcoming of current methods applied. However, the method of choice is highly dependent on the availability of facilities and resources. Among the detection methods, reverse transcription-polymerase chain reaction (RT-PCR) is the most favourable method used for detecting AIV. However, a constant review of the virus genome is crucial to maintain the assay’s sensitivity. More comprehensive research and evaluation study are needed for new diagnostic approaches.
Keywords: Avian influenza, detection methods.
Aims: Brewer’s rice is one of the by-products from rice processing industry that is rich in bioactive compounds but currently underutilized. Exploitation of agro-industrial by-products as substrates in solid-state fermentation processes provides value-addition to these underutilized by-products. The purpose of this research is to evaluate the potentiality of brewer’s rice as a source of cosmeceutical or cosmetic bio-ingredient by utilizing solid-state fermentation process.
Methodology and results: Brewer’s rice was submitted to solid-state fermentation with Aspergillus oryzae from MARDI’s Collection of Functional Food Culture (CFFC). Extracts of unfermented and fermented brewer’s rice were later subjected to determination of biological content and biological activities, as well as measurement of their phenolic and organic acids content. The extract of fermented brewer’s rice exhibited an increase in total phenolic and total flavonoid content and showed enhanced 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging and ferric-reducing activities. Additionally, it was also found that the tyrosinase and elastase inhibition activities of fermented brewer’s rice extract is significantly higher with nearly 7- and 57-fold, respectively, than the unfermented extract. Ferulic and kojic acid – two of the most important compounds in cosmeceutical formulations, were also detected in fermented brewer’s rice extract.
Conclusion, significance and impact of study: Antioxidant, anti-pigmentation and anti-wrinkle properties of brewer’s rice were successfully enhanced by fermentation with A. oryzae. Fermented brewer’s rice extract has high potential to be developed as functional bio-ingredient for cosmeceutical as well as nutraceutical products.
Keywords: Aspergillus oryzae, brewer’s rice, fermentation, cosmeceuticals
Aims: A rare marine-derived actinomycete, Plantactinospora sp. KBS50, has been identified as a potential source of bioactive secondary metabolites compounds. The present study aimed to evaluate the secondary metabolites biosynthetic capability of strain KBS50 using the One Strain Many Compound (OSMAC) fermentation strategy.
Methodology and results: Strain KBS50 was fermented in a basal medium (ISP2) supplemented with selected biological and chemical elicitors, as well as cultivation at different pH value and incubation temperature. Statistical analysis revealed that the antimicrobial activities were significantly increased, as compared to the basal medium, ISP2. Similarly, the comparative High Performance Liquid Chromatography (HPLC) analysis showed an increase in secondary metabolites production, as well as the detection of potential new metabolites, particularly from the crude extracts of ISP2 medium supplemented with 1% (w/v) sodium chloride and with the culture filtrate of Aspergillus niger. The bioassay-guided fractionation showed that the extract of strain KBS50 contains multiple compounds with antibacterial activity against the Gram-positive strains. Further fractionation led to the isolation of two semi-pure compounds (compound 3 and 4) with bactericidal properties against Staphylococcus aureus. The Minimum Inhibitory Concentration (MIC) values of compound 3 and 4 were recorded at 7.81 µg/mL and 62.50 µg/mL, respectively. The minimum bactericidal concentration (MBC) for compound 3 was recorded at 15.63 µg/mL while the MBC for compound 4 was recorded as 125.00 µg/mL.
Conclusion, significance and impact of study: The OSMAC fermentation strategy used in this study had successfully enhanced the detection of antibiotics and secondary metabolites from Plantactinospora sp. KBS50. The bioassay-guided fractionation further established the capability of strain KBS50 as a source of bioactive secondary metabolite compounds with potent antimicrobial activity.
Keywords: Marine actinomycete, elicitors, OSMAC, antimicrobial activity
Aims: Aerobic rice is a potential crop introduced to encourage water conservation in rice planting. However, a decline of aerobic rice yield has been reported and thus this study was initiated with the aim to observe the response of microbial community in this environment which are exposed to various plant growth stage and soil types.
Methodology and results: To determine the effect of soil types such as peat and sandy clay loam on microbial community. A total of four growth stages were tested namely vegetative, reproductive, ripening and maturing. To determine the influence of growth stages and soil types towards microbial community in aerobic rice, Biolog Ecoplate™ technique was used to quantify the response of microbial community through microbial functional diversity and carbon source utilization. The abundance of culturable aerobic bacteria, fungi, actinomycetes, nitrogen-fixing microorganism and phosphate-solubilizing microorganism were determined using five different selective media. Soil physical and chemical properties as well as total nitrogen in plant tissues were also determined. It was found that microbial functional diversity during plant growth (except for microbial evenness) varied between the soil types. Correlation analysis revealed different relationships between carbon source utilization and microbial functional diversity in both soil types.
Conclusion, significance and impact of study: Microbial community in rhizosphere responded according to plant development which is primarily determined by soil type. Therefore, it is concluded that soil type particularly the soil physical and chemical properties are important factors in shaping the microbial community by directly influencing the rhizosphere environment.
Keywords: Microbial functional diversity, CLPP, MRIA 1, peat, sandy clay loam
Aims: This study determined the optimum temperature for cell immobilization, the optimum time of fructose production by immobilized cell, and immobilized cell stability against repeated use in fructose production.
Methodology and results: Research on cell immobilization of Streptomyces griseus and the variant have been done. The S. griseus variant was resulted from UV mutation. The variant was able to produce fructose as hydrolysis product 3 times as much after 30 min. Heating was done at 50, 60, 70, 80 and 90 C. The fructose production was performed at intervals of 4 h for 32 h. The results showed that the optimum cell immobillization temperature of S. griseus and its variant was 80 C. The optimum time of fructose production by immobilizing cell of S. griseus was 28 h and its variant cells was 24 h. Immobilized cells of S. griseus can be reused for 6 × 28 h to produce fructose compared to variants cells was 5 × 24 h, respectively.
Conclusion, significance and impact of study: This study reported that immobilized cells of S. griseus can be reused and its variant were highly advantageous in the production of fructose. The amount of fructose production was increased as compared to the conventional method and the cost of production could be reduced as well.
Keywords: Cell immobilization, fructose, Streptomyces griseus, variant
Aims: To determine the optimum culture incubation time for β-glucanase and chitinase production by Bacillus subtilis as well as optimum pH and temperature condition for enzymatic activity against Ganoderma boninense. The suitable solvent (methanol, ethyl acetate or hexane) for the extraction of bacterial metabolites from B. subtilis were also determined.
Methodology and results: In vitro antagonistic activity of antifungal metabolites derived from B. subtilis to inhibit the growth of G. boninense was evaluated based on time of culture incubation, extraction solvent of the metabolites, and enzymatic treatments conditions including pH and temperature. The results showed that β-glucanase could be optimally produced (with a specific activity 4.222 U/mg-protein) after 28 h of incubation. The optimum pH and temperature for the activity of β-glucanase were 7.5 and 45 °C respectively when 1% laminarin used as the substrate. B. subtilis showed optimum chitinase activity (0.0514 U/mL) after 8 h of incubation. Optimum pH and temperature of chitinase were at pH 6.0 and 40 °C, respectively using 1% colloidal chitin as the substrate. β-glucanase crude enzyme showed strongest antifungal activities against the mycelial growth of G. boninense better than crude enzyme of chitinase with an inhibition rate of 47.75% at 5 days of incubation. Furthermore, cultivation of B. subtilis over 48 h produced antifungal metabolites which could inhibit the growth of G. boninense the most. The best solvent to extract metabolite from B. subtilis was identified as ethyl acetate that rendered an inhibition value of 38.91%.
Conclusion, significance, and impact of study: Bacillus subtilis could be a potential biological control agent against G. boninense.
Keywords: Bacillus subtilis, Ganoderma boninense, antifungal, β-glucanase, chitinase
Aims: The current gold standard method for the detection of Campylobacter jejuni is the culturing method followed up by immuno-based detection method, of which, the ELISA is the most often used. Many commercial detection methods based on ELISA use monoclonal antibody preparations although polyclonal antibody can be more sensitive and cheaper to produce. In this study, a comparison of indirect and sandwich ELISA-based detection methods for the detection of C. jejuni using a commercial monoclonal and polyclonal antibody preparations was explored.
Methodology and results: An indirect and sandwich ELISA-based methods for the detection of C. jejuni was carried out using the same concentration of antibody (5 µg/mL) and the same concentration of the bacterium at 1×109 CFU/mL. At the pre-screening for optimum concentration of antibody to be used for both assay formats, the commercial monoclonal preparation gave a poor absorbance value of about 0.112 compared to 1.582 for the polyclonal antibody preparation. Hence, the use of the monoclonal antibody was not pursued further. Using the polyclonal antibody, the calculated Limits of Detection (LOD) value obtained for the indirect and sandwich ELISA methods were at 1.6×104 CFU/mL and at 1.29×104 CFU/mL, respectively, which are more sensitive than commercially used methods. The results of the specificity test obtained from the developed polyclonal antibody were then tested against other common food borne bacterial pathogens such as Salmonella Typhimurium, Listeria monocytogenes and Escherichia coli tested using the sandwich ELISA format indicated that the responses by other bacterial genus were relatively low with the translated cross-reactivity percentages of 1.78, 2.36, and 6.87 %, respectively.
Conclusion, significance and impact of study: The results indicated that the developed system using a polyclonal antibody preparation can be more sensitive than monoclonal preparation. In addition, it is also specific towards Campylobacter while the monoclonal antibody preparation fares poorly.
Keywords: Campylobacter jejuni, campylobacteriosis, ELISA, polyclonal antibody, monoclonal antibody
Aims: The objective of this study is to identify the causal agent of a new fruit rot disease on jackfruit which was observed in the jackfruit-growing area in Taman Kekal Pengeluaran Makanan (TKPM), Pahang State of Malaysia in late 2016. The disease has been continuously spreading and caused huge economic loss to jackfruit farmers in Malaysia.
Methodology and results: Bacterial strains isolated from the disease plant were preliminary identified using basic morphological and physiological test and confirmed by polymerase chain reaction (PCR) and sequencing of the 16S rRNA gene. The isolates from infected tissue were Gram-negative and motile rods bacteria producing circular, mucoid colonies on LB medium that are 2 mm wide after 48 h at 28 °C. It appeared creamy to white in colour on NA medium with more watery consistency. The 16S rRNA was amplified for the isolated strains and sequences were compared with the NCBI database using BLAST. The results showed 97 to 99% identity similarity to Dickeya fangzhongdai, strain JS5 (accession no. KT992690). Phylogenetic analysis indicated that the isolates from this study were clustered together in the clade of D. fangzhongdai. Sequence data from isolated strains were deposited in GenBank (accession no. MH197139, MH842152 and MH842153). Characteristic symptoms of fruit rot disease appeared after 2 days of post inoculation though Koch’s postulate.
Conclusion, significance and impact of study: To the best of our knowledge, this is the first report of a new bacterial fruit rot disease of jackfruit caused by species of Dickeya in Malaysia. The bacterium is now considered as one of several bacterial causing diseases which impacted major loses of jackfruit industry in Malaysia.
Keywords: Jackfruit, Dickeya fangzhongdai, fruit rot, PCR, bacterial disease
Aims: Fermented mango leaves of Chokanan variety was produced using selected symbiotic culture of bacteria and yeast (SCOBY) from MARDI’s Collection of Functional Food Cultures (CFFC). The aim of this work was to investigate its functional benefits as food remedy to reduce the risk of food poisoning illness incidence.
Methodology and results: Five species of foodborne pathogens: Escherichia coli O157:H7 UPMEC32 (local isolate), Salmonella typhimurium ATCC®53648™, Salmonella enteritidis MDC15 (local isolate), Listeria monocytogenes ATCC®51772™ and Streptococcus gallolyticus (ATCC®9809™) were selected to examine the antimicrobial effect of fermented mango leaves beverage by means of agar well diffusion assay and broth microdilution method to determine its minimum bactericidal concentration (MBC>99). In comparison with chemical inhibitor (acetic acid, 1%) and antibiotic (Penicillin streptomycin, 1%), the agar diffusion assay results confirmed the inhibition efficacy of fermented mango leaves beverage against all five foodborne pathogens tested. Particularly, fermented mango leaves beverage was showing a significant inhibitory effect (P<0.05) against S. gallolyticus, whereas both acetic acid and penicillin streptomycin have no inhibitory activities at all towards this pathogen. Another antimicrobial activity assay using broth microdilution method also confirmed the 100% inhibition effect of fermented mango leaves beverage against these selected pathogenic microorganisms. Furthermore, the efficacy retained 100% inhibitory activities even though the fermented mango leaves beverage has been diluted to 50%. Synergetic effect of significant amount of multiple organic acids present in fermented mango leaves beverage were the main factors contributing to its potent antimicrobial properties and improvement taste after fermentation. On the contrary, little or no antimicrobial inhibitory activity was observed in all non-fermented mango leaves beverages treated samples.
Conclusion, significance and impact of study: This finding indicates that the potential of fermented mango leaves beverages as prophylaxis measures to reduce the risk of food poisoning incidence as it has shown a good antimicrobial effect against selected foodborne pathogens. Moreover, this fermented mango leaves beverage are more tasteful after gone through the microbial fermentation process. It is recommended to consume daily to reduce the incidence of food poisoning illness.
Keywords: Mango leaves, foodborne pathogens, antimicrobial activity, broth microdilution, fermentation
Aims: Oil sludge is one of pollutant sources in the environment. Bacterial abundance, interaction, and compatibility of environmental factors ensure the success of biodegradation. The purpose of this study was to determine the effectiveness of bacterial consortium in degrading oil sludge using bioslurry method.
Methodology and results: The research design used was completely randomized design 4×5 with variation of bacterial consortium concentration and incubation time. Composition of contaminant and liquid phase in bioslurry method was 1:9 ratio with aeration, at room temperature. The liquid phase comprises distilled water with the addition of 2% (v/v) of molasses as nutrient for bacterial growth. Bacterial growth was evaluated using the Total Plate Count (TPC) method. Total Petroleum Hydrocarbon (TPH) measurements were evaluated using the gravimetric method while the oil sludge hydrocarbon component was evaluated by Gas Chromatography Mass Spectrophotometry (GCMS). The pH and temperature data were analyzed descriptively while TPC and TPH data were analyzed using Two Way ANOVA (α=0.05). The bacterial consortium could grow on oil sludge hydrocarbon substrate with a range of temperature of 29 °C-32 °C and an optimum pH of 7. Biodegradation of TPH was 70.48% at consortium concentration of 15% in 14 days of incubation.
Conclusion, significance and impact of study: Biodegradation of oil sludge using a bacterial consortium by bioslurry method is one of the effective methods to reduce pollutants in the management of oil sludge.
Keywords: Bacterial consortium, biodegradation, bioslurry, molasses, oil sludge
Aims: A study had been conducted to isolate lactic acid bacteria (LAB) from Malaysian stingless bee gut and to determine their population in 4 stingless bee species. The isolated LAB was subjected to antimicrobial activity against selected bacterial pathogens and antibiotic resistance towards several antibiotics.
Methodology and results: Lactic acid bacteria isolated from the gut of 4 Malaysian stingless bee species (Heterotrigona itama, Geniotrigona thoracica, Tetragonula laeviceps and Tetrigona melanoleuca) were subjected to antimicrobial activity test against selected pathogenic bacteria, antibiotic resistance assay and identification of potent LAB through molecular 16S rRNA gene sequencing. A total of 99 putative LAB isolated from 4 stingless bee species were found to exhibit LAB characteristics such as Gram positive, oxidase negative and catalase negative. Out of 99 isolates, only 7 LAB isolates viz. TIS 5, TIS 25, TID 18, TTD 6, TLH 13, TLH 16 and TMH 2 exhibited strong to intermediate inhibition against Staphylococcus aureus, Eschericia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Bacillus cereus, and Bacillus subtilis. The antibiotic susceptibility test demonstrated that all 7 isolates were not susceptible to streptomycin (10 µg), gentamycin (10 µg), tetracycline (30 µg) and kanamycin (30 µg). Nevertheless, these 7 isolates exhibited intermediate susceptibility to antibiotic penicillin G (10 µg), carbenicillin (100 µg) and ampicillin (10 µg). These 7 potent LABS were identified genotypically as Lactobacillus plantarum (TIS 5 and TIS 25), Fructobacillus tropaeoli (TID 18 and TTD 6) and Pediococcus pentosaceus (TLH 13, TLH 16 and TMH 2).
Conclusion, significance and impact of study: Findings from this study demonstrated the stingless bee’s gut as a reservoir for LAB with anticipating antimicrobial properties and tolerance to certain antibiotics.
Keywords: Lactic acid bacteria, insect gut microbiota, meliponine, human pathogen, in vitro
Aims: The present study was designed to evaluate in vitro antifungal activity of plant extracts against Curvularia sp., a causative agent of leaf blotch in local purple sweet potato crops.
Methodology and results: The plants were selected on the basis of commonly used traditional remedies. Various dilutions, 1/2, 1/4, 1/6, 1/8 and 1/10 of black pepper, garden croton, garlic, tobacco and turmeric extracts were used for screening. The lesion characteristics on purple sweet potato leaves were collected from plots in MARDI Bachok. The “poisoning agar technique method” was used to get the antifungal activity. The results of antifungal activities were reported in terms of inhibition of mycelial growth of the test fungus. Out of five types of plant extracts used, only garlic and tobacco showed significantly high antifungal activity against the test pathogen based on poisoned food technique. Garlic extract showed complete inhibition (100%) at 1/2 dilution and more than 94% growth inhibition at concentrations as low as 1/10 dilution after seven days of incubation. However, black pepper and turmeric extracts showed moderate inhibition (20-70%) whereas, no inhibition was recorded in 1/8 and 1/10 dilution of garden croton extract.
Conclusion, significance and impact of study: Our findings suggested that garlic extract is the most potential antifungal agent against Curvularia sp. and can be used as bio-fungicide thus would reduce the dependency on synthetic fungicides by farmers.
Keywords: Antifungal, purple sweet potato, Curvularia sp., plant extract
Aims: Bacterial heart rot (BHR) disease caused by Erwinia Chrysanthemi or the new nomenclature Dickeya Zeae was identified as the lethal disease of pineapple and caused massive losses for the farmers due to non-satisfactory solutions. Thus, this study aims to understand the disease dissemination pattern and screen for tolerance pineapple variety prior to establishment of disease management strategies.
Methodology and results: Dissemination of BHR disease was observed visually in 2 study plots consisting 200 plants in each plot. Single plant inoculation of the pathogen was done in each plot namely Plot A at the edge and Plot B at the middle. Disease incidence was recorded at weekly interval for 12 weeks. The pattern of disease spreading in both plots was then mapped based on the results. Separately, 8 commercial pineapple varieties (Maspine, N36, MD2, Morris, Sarawak, Kristal, Gandul and Josapine) were screened for their resistance towards BHR. The varieties screening study was carried out using complete randomized block design. Overall, disease incidence (DI) was observed lower in plot A compared to Plot B. Percentage of DI in Plot A increased continuously from week 1 to 12, but in plot B the DI was stagnant starting from week 3 onwards. This study revealed that there is highly significant difference in percentage of infection between varieties tested. Josapine and MD2 were the most infected varieties based on lesion on plant. Both were found susceptible to BHR. Besides that, Chrystal Honey, Maspine and Sarawak varieties were less infected and classified as moderately resistance compared to other varieties.
Conclusion, significance and impact of study: Inoculum source was recognized as determinant factor for dissemination of BHR. Aggregation pattern was observed, and disease spreading was severe when disease started from the edge of the plot compared to in the middle. These findings will help farmers to choose the varieties of interest and plan for disease control measure based on first observed disease symptom in their field. This study is also important to researchers and plant breeders for varietal improvement in the future.
Keywords: Bacterial heart rot, Erwinia Chrysanthemi, pineapple, Josapine, MD2, Dickeya sp
Dissemination pattern of bacterial heart rot (BHR) disease and screening of the disease resistance among commercial pineapple varieties in Malaysia
- Muhamad Nor, A. A., Zainol, R., Abdullah, R., Jaffar, N. S., Abdul Rasid, M. Z., Laboh, R., Ahmad Shafawi, N. , Abdul Aziz, N. B.