MALAYSIAN JOURNAL OF MICROBIOLOGY
Aim: The aim of this study was to assay for the biogenic amine-producing capacity of bacteria isolated from Proteinous food.
Methodology and results: Previously characterized bacterial isolates (Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae) obtained from proteinous food samples (smoked fish and yoghurt) were subjected to Proteolytic analysis using nutrient agar supplemented with 0.2 g/mL casein and decarboxylase activity using nutrient broth supplemented with 0.004 g/mL amino acids (histidine, tyrosine, asparagines, leucine and lysine). Isolates that expressed proteolytic and decarboxylase activities were screened for biogenic amine producing capacity using decarboxylase broth which was supplemented with an amino acid (tyrosine). Biogenic amines obtained in this research were classified into primary amine and secondary amine based on their qualitative characteristics. Confirmatory and quantitative analysis of biogenic amines produced was done using high-performance liquid chromatography. The confirmatory screening revealed the presence of methylamine, ethylamine, putrescine, cadaverine, histamine, spermidine, phernylethylamine, spermine, agmatine, tyramine, dopamine, tryptamine, norepinephrine and serotonin respectively. Total biogenic amines produced by S. aureus was 70.12 mg/kg, K. pneumoniae (62.58 mg/kg) and E. coli (56.57 mg/kg) respectively.
Conclusion, significance and impact of study: Enzymatic decarboxylation of free amino acids and other metabolic processes by the test organisms (S. aureus, E. coli and K. pneumoniae) leads to production of biogenic amines which can be used as a quality indicator in food in terms of degree of spoilage, use of non-hygienic raw material and poor manufacturing environment. Thus, effect of biogenic amines obtained in this research would be determined by individual toxicological threshold which can be extremely variable from few mg/kg in sensitive person to several hundred mg/kg in healthy person. The concentrations of each biogenic amine quantified are within the limit but their toxic effects depend on the type of amine, the presence of modulating compounds and the efficiency of an individual’s detoxification mechanism.
Aims: The coagulase-negative staphylococci (CoNS) are a group of Staphylococcus that is gaining clinical significance as major agents of nosocomial infections, especially amongst neonates and immuno-compromised patients. The identification of CoNS remains problematic, and there has been little information on their molecular genotyping. The overall aim of this study was to evaluate Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR) as a rapid and cost-effective tool for the genotyping of CoNS isolates from within a hospital setting.
Methodology and results: A total of 200 isolates of CoNS were collected from Hospital Tuanku Ampuan Rahimah, Klang, Malaysia and identified via sodA gene sequence analysis. Genetic diversity among the isolates was evaluated using the ERIC-PCR. The most frequently isolated species was S. epidermidis (37%) followed by S. haemolyticus (30%), S. hominis (18%) and S. capitis (8.5%). ERIC-PCR was found to be efficient for the differentiation of S. hominis isolates with a discriminatory index (DI) of 0.949 and satisfactory for S. epidermidis isolates at DI of 0.808. Poor discriminatory power was observed in S. haemolyticus (0.377) and S. capitis (0.111). The majority of the S. haemolyticus and S. capitis isolates were found to be genetically homogenous which imply that the source of these infections are due to hospital-derived contaminants. In contrast, the S. epidermidis and S. hominis strains displayed high genetic diversity suggesting the presence of different endemic strains and inflow of exogenous strains brought in by non-local residents.
Conclusion, significance and impact of study: ERIC-PCR is a useful tool to differentiate and track different selected species of CoNS.
Aims: Leptospirosis is an infectious disease that is endemic to many tropical regions. Large epidemics usually happen after heavy rainfall and flooding. This potentially fatal zoonosis is caused by pathogenic bacteria belonging to the genus Leptospira. Leptospirosis can be diagnosed using specific biomarkers such as target genes and virulence indicators that are well preserved across various Leptospira spp., including those that are prevalent in clinical samples and in the environment. To date, several pathogenicity-determinant genes, including lipL32 and lipL41, have been described and used for diagnosing leptospirosis. However, prevalence of these genes in leptospiral strains is unclear.
Methodology and results: In the present study, we assessed the distribution of eight pathogenicity-determinant genes in reference Leptospira strains and environmental isolates in Malaysia, by polymerase chain reaction (PCR). We found that only lipL32 and ligB were consistently expressed in all pathogenic Leptospira strains compared with the other tested genes. Moreover, our results suggested that the use of lipL41, lipL21, ompL1, lfb1, ligA, and ligC as biomarkers could incorrectly misdetect pathogenic Leptospira strains present in the environment.
Conclusion: Thus, our results suggest that the pathogenicity-determinant genes lipL32 and ligB can be used as biomarkers for detection pathogenic Leptospira.
Aims: The most common transmission route of hepatitis C virus (HCV) is via blood transfusion. Therefore, the screening of HCV is necessary to be performed regularly for all the volunteer blood donors. The prevalence of HCV subtypes varies in different geographical areas. The aim of this study is to identify the HCV genotypes of the HCV-RNA positive samples and performed serological and molecular characterization of HCV among blood donors from blood transfusion center of Tuban, East Java, Indonesia collected during the year of 2015.
Methodology and results: All blood donor samples were screened by enzyme-linked immunosorbent assay (ELISA) for anti-HCV. Reverse Transcription- Polymerase chain reaction (RT-PCR) was performed to detect the HCV-RNA. Subsequently, the HCV-RNA positive samples were genotyped using direct sequencing followed by subtype/genotype and phylogenetic analysis. Of the 500 blood samples, 7 were positive for anti-HCV antibody (1.4%) and 6 out of 7 (85.71%) were determined to be HCV-RNA positive. Among HCV-RNA carriers, genotyping showed genotypes 1 was the most prevalent. HCV subtypes 1a and 1b were detected in total of 4 out of 6 individuals (66.67%), two individuals for each. HCV subtypes 2a and genotype 1 were the least frequent among blood donors (each counted for 16.67%, respectively).
Conclusion, significance and impact for study: The prevalence of HCV found in this study is considerably low. The identification of genotypes 1a and 1b as major HCV genotypes circulating in blood donors in the region of Tuban may contribute in a better medical management towards HCV carriers.
Aims: Staphylococcus aureus is the most common pathogen found in humans, animals and foods worldwide. Vegetables contain essential vitamins, minerals, and fibres that may aid in protecting humans from chronic diseases and promote good health. This investigation aimed to find the prevalence of S. aureus contamination and antimicrobial resistance pattern of isolates from leafy vegetables in Peninsular Malaysia.
Methodology and results: A total of 397 samples, comprised of 16 different vegetables, were obtained from vendors in selected wet markets. Of the 397 samples, S. aureus was detected in 42 samples (10.6%) in which 9 (21.4%) were positive for methicillin-resistant Staphylococcus aureus (MRSA). The S. aureus isolates showed 52.3% resistance to tetracycline, followed by kanamycin (40.5%), penicillin G (35.7%), streptomycin (33.3%), oxacillin (21.4%) and cefoxitin (19.0%). The multiple antibiotic resistance indexes of S. aureus isolates varied from 0.21 to 0.50. The predominant antimicrobial resistance profiles of S. aureus were PDaOxSTeL (n=5), PDaSTeCe (n=4), TeKCnSxtC (n=3) and TeKCipQd, respectively.
Conclusion, significance and impact of study: The findings of this study revealed the consumption of raw or minimally prepared fresh leafy vegetables could be a possible source of infection with antimicrobial-resistant S. aureus.
Aim: Dandruff is characterized by the white flakes in the hairs and can be caused by dry skin and mainly by fungal growth of Malassezia yeasts. To treat this condition mainly synthetic type of active ingredient shampoos are used which gave severe adverse effect toward users like hair fall and weakening of the hair roots. In this study, we formulate a shampoo containing an active ingredient “Propolis” an antimicrobial agent which is also known as bee glue. Formed by the combination of bee wax and flower exudate collected from the flower bud.
Methodology and results: In this study, propolis extracts have been used as the antimicrobial agent in the shampoo formulation for treating dandruff-causing bacteria, Staphylococcus aureus. Interestingly, the developed propolis shampoo showed is 10-fold more effective against S. aureus compared to the propolis extracts alone. This is due to the presence of Tween 80 as the surfactant used in the formulation which adds to this antibacterial effect. The formulated shampoo was also compared with the commercially available shampoo (Safi Shayla brand) for physicochemical properties. Overall evaluation of the shampoo with propolis found to have pH (6-7), good foaming ability, less wetting time, a good percentage of solid content and viscosity. Also, the formulated shampoo has greater stability under accelerated room temperature and accelerated the ageing condition.
Conclusion, significance and impact of study: This study demonstrated the propolis extracted can be used as a potential antimicrobial agent. As it came from the natural resource the acceptance will high among the consumers.
Aims: Rice blast disease caused by Pyricularia oryzae is one of the major biotic diseases of rice in Sarawak, Malaysian Borneo. This study aims to isolate and characterize rice blast fungus obtained from infected leaf collected from four different divisions in Sarawak, viz, Miri, Serian, Sri Aman, and Kuching.
Methodology and results: Twelve succeeded isolates were pre-identified as P. oryzae by morphological characteristics of spores, followed by verification through (internal transcribed spacer) ITS sequencing. The isolates were evaluated for morphological characteristics, growth rate and sporulation rate, which were grown on two types of media, (filtered oatmeal agar) FOMA and (potato dextrose agar) PDA. Morphological characterization showed that the colony surface of the different isolates varied from smooth and fluffy to rough and flattened mycelia; some were with the present of concentric rings, and some with aerial mycelia. The growth rate and sporulation rate of each isolate varied based on types of media used. Most of the isolates grew faster on PDA than on FOMA but produced higher number of spores on FOMA as compared to PDA.
Conclusion, significance and impact of study: This preliminary study showed that there were variations observed based on morphological and physiological characterization for the different isolates collected in Sarawak, Malaysian Borneo. This study is the first step towards understanding variation in the population of P. oryzae from Sarawak.
Aims: Mycorrhiza has an important role as a biocontrol agent. Its association with Phalaenopsis amabilis was molecularly identified through rDNA-ITS sequence analysis. The aims of the study were to identify molecular of orchids mycorrhiza isolate from native tropical orchids in Indonesia, conducted as one of native orchid conservation efforts in Indonesia.
Methodology and results: One group of Ceratobasidium were isolated from the root of orchid plant in Yogyakarta based on morphological and microscopical analysis. The results of molecular analysis showed 600-750 bp of DNA products located on the ITS1-5.8S-ITS4 region. The sequenced products showed insertion and substitution occurances, which may result in strain diversity and possible variation. Reconstruction of phylogenetic trees using Maximum Parsimony and Bootstrap-1000 approach showed showed the Indonesian isolate is at the basal clade and already far apart from the other isolates.
Conclusion, significance and impact of study: Isolate Ceratobasidium from Yogyakarta, Indonesia successfully isolated based on identification of rDNA-ITS sequences. Results of this study were expected to become the basic information in an effort of native orchid cultivation and protection against infectious diseases in Indonesia. The study was the first to report regarding Ceratobasidium isolated from native tropical orchids in Indonesia.
Aims: The present study deals with the isolation and identification of lactase producing probiotic strains from camel and sheep milk, determination of the enzyme activity by β-galactosidase assay (Miller Assay) in the presence of garlic, peas, onion and leeks extracts containing inulin as a prebiotic component.
Methodology and results: The two isolates were screened for lactase producing ability to degrade lactose on MRS agar at 37 °C. These were identified as Lactococcus lactis from camel (Marecha) milk and Lactobacillus casei from sheep (Kajli) milk through morphological and biochemical tests using MRS medium. The optimized pH and temperature of both strains were 6 and 35 °C, respectively. Among the three concentrations used (0.2 %, 0.4 %, 0.8 %), the optimal concentration of inulin rich onion and leeks extracts was 0.8 % for maximum growth of L. casei and of the peas extract for L. lactis growth. 0.2% garlic extract was more effective prebiotic source for L. lactis growth. 0.8% commercial inulin used as a positive control was less effective as compared to plant extracts used in the study. With o-nitrophenyl-β-D-galactoside) used as a substrate in the enzyme assay, maximum lactase activity obtained with 0.8 % concentration of garlic extract is 7.10 Miller Units as compared to the peas extract with 6.17 Miller Units from L. lactis. Lactobacillus casei has produced more lactase, 6.85 Miller units with onion extract than with leeks extract, 6.43 Miller Units. Pure commercial inulin used as a control has given maximum enzyme activity as 9.14 Miller Units at 0.2 % concentration.
Conclusion, significance and impact of the study: It is concluded that the extracted prebiotic may enhance lactase activity of the probiotics to supplement the development of food products for lactose intolerant patients.