MALAYSIAN JOURNAL OF MICROBIOLOGY
Aims: A study on biosorption ability using encapsulated endophytic fungi has been carried out to investigate its biosorption potential in removing heavy metals. Biosorption has emerged as an alternative bioremediation process to remove and sequester heavy metal ions from polluted water. An endophytic Pestalotiopsis sp. (isolated from Nypa fruticans) was found to be able to resist Copper (Cu), Chromium (Cr), Lead (Pb) and Zinc (Zn) upto 1,000 ppm and thus the aim of this study was to investigate the biosorption ability using encapsulated live and dead Pestalotiopsis sp. biomass (at pH 4-6) to remove heavy metals. Additionally, a proteomic study was conducted to investigate down- and up-regulation expression levels of proteins under the treatment of the heavy metals.
Methodology and results: Encapsulated live fungal biomass displayed higher efficiency in removing Chromium at pH 5 and 6, while both encapsulated live and dead biomass were able to remove Lead at pH 4 and 5 and Copper at pH 5. Five (5) proteins of interest were identified via MALDI-ToF analysis. Among the proteins identified, multidrug resistance protein (MRP homolog) was up-regulated in the presence of Lead.
Conclusion, significance and impact of study: The data obtained in this study provides an initial understanding of the biosorptive and defensive mechanisms of Pestalotiopsis sp. under heavy metal stress.
Aims: A combination of the antimicrobial drug with the herbal derived antifungal agent was exploited as alternative therapeutic approaches for infectious diseases caused by drug resistant strains. In this study, we determine the antifungal effects of eugenol alone and in combination with fluconazole against Candida sp.
Methodology and Results: Candida strains including fluconazole resistant (C. parapsilosis ATCC 22019 and C. albicans U821/10) and susceptible strains (C. tropicalis U624/10 and C. glabrata U71/1) were used in this study. By broth microdilution technique, eugenol exhibited antifungal activity with MIC and MFC against Candida sp. tested ranging from 0.5-1 mg/mL. The interaction between eugenol and fluconazole against Candida sp. was determined by chequerboard microtiter technic. Eugenol decreased the MIC of fluconazole against Candida sp. tested. No antagonism was observed in strains test.
Conclusion, Significance and Impact of study: From these results, eugenol displayed a promising antifungal effect alone as well as combination with fluconazole against Candida sp.
Aims: Brown spot disease is among the important crop diseases of rice caused by the infection of a pathogenic fungus, Cochliobolus miyabeanus that results in yield losses. Nowadays, limited studies on volatile organic compounds (VOCs) have been carried out using pathogenic fungal isolate. Hence, this study was conducted to identify VOCs produced by C. miyabeanus wild-type isolate, WK1C, a causal agent of brown spot disease using gas chromatography-mass spectrometry (GC-MS).
Methodology and results: Fungal isolate WK1C was cultured on potato dextrose agar (PDA) and in potato dextrose broth (PDB) for extraction. The extracts were analysed using GC-MS and the profiles of VOCs were obtained. Cochliobolus miyabeanus WK1C isolate showed a significant presence of various types of organic compound including ester, alcohol, phenol, alkane, alkene, ketone, carboxylic acid, amide and aldehyde.
Conclusion, Significance and Impact of Study: This study important for a preliminary assessment of VOCs profiles of C. miyabeanus, a causal agent of brown spot disease. In order to identify the compounds contribute to pathogenicity, further study can be conducted to identify the virulence factor of brown spot disease using different approaches.
Aims: Metal transcriptional regulators controlled the regulation of metal ion homeostasis in bacteria genera. Cd(II)/Pb(II) transcriptional regulator is one of the member of MerR family found in Alcaligenes faecalis SF-S1-60 (PbrT-AF).
Methodology and results: The PbrT-AF gene with 432 bp open reading frame was successfully isolated from genomic DNA of A. faecalis using polymerase chain reaction (PCR) analysis. This gene was phylogenetically grouped with A. alcaligenes species using PHYLIP version 3.69 by the neighbor-joining method with 1000 bootstrap replicates. Phylogeny analysis shows that these proteins have distinct amino acids compared to Cd(II)/Pb(II) regulators from different species. The structure of PbrT-AF shows similar conformation with other members of MerR family using MODELLERv9.17. We also demonstrated that the expression of Pbrt-AF in Escherichia coli BL21 were able to increase the bacteria tolerance towards Pb up to 1000 ppm.
Conclusion, significance and impact of study: This result suggests that PbrT-AF promotes cell adaptation and tolerance towards Pb toxicity.
Aims: This study aims to detect the effect of nano-sized calcium carbonate as an ingredient in growth medium on the production of alkaline protease by Streptomyces spororaveus. The proportional relationship between highly production of alkaline protease and calcium carbonate nanoparticles emphasizes the unique and super properties of nanotechnology that applied in all field.
Methodology and results: The high production of protease from S. spororaveus accompanied with presence of calcium carbonate nanoparticles as one of growth medium's constituents. Both qualitative and quantitative tests for proteolytic activity proved this fact. Agar-well diffusion method revealed that, the proteolytic activity with calcium carbonate nanoparticles (45 mm) is higher than that with calcium carbonate (30 mm). Calcium carbonate nanoparticles led to 150 µg/mL of protease, while calcium carbonate led to 65 µg/mL only. The crude protease was purified by ammonium sulphate precipitation and gel filtration column chromatography using Sephadex G-100. The purified protease was separated by SDS-PAGE as a single band at 30 kDa. The highest proteolytic activity was obtained at pH 8.5 and 45 °C as optimum environmental conditions. The purified protease has inhibited the growth of Candida albicans ATCC-10231 and Aspergillus brasiliensis ATCC-16404 at 8 mm and 10 mm of inhibition zone respectively.
Conclusion, significance and impact of study: Calcium carbonate nanoparticles in the composition of starch nitrate broth is good stimulus for highly proteolytic activity of S. spororaveus. Shake-flask fermentation method proved that, the concerned protease is an alkaline and thermostable up to 70 °C. However, the best pH and temperature values are 8.5 and 45 °C, respectively. This study can be applied to manufacture a modified starch nitrate broth medium for highly production of proteases from Streptomyces bacteria.
Aims: The aim of this study was to screen bacterial endophytes with antibacterial and enzyme activity from mangrove leaves of Indonesia.
Methodology and results: Bacterial endophytes were isolated and evaluated for antibacterial activity against five strains of pathogenic bacteria. Enzymatic Index (EI) was measured to evaluate the production of protease, amylase and cellulase. Hemolysin test was performed on Blood Agar and the sensitivity to antibiotic was performed. Bacterial endophyte Strain 1-1 isolated from Bruguiera gymnorrhiza showed strong inhibition against Escherichia coli, Salmonella sp., Staphylococcus aureus and Pseudomonas aeruginosa with inhibition zone of 12.6 ± 1.4, 8.8 ± 4.1, 12.5 ± 2.3 and 8.4 ± 0.9 mm respectively. Isolate 1-16 which also isolated from B. gymnorrhiza exhibited antibacterial activity against E. coli and P. aeruginosa, while Isolate 6-10 isolated from Avicennia lanata exhibited strong inhibition on Salmonella sp. (13.1 ± 3.3 mm). All of those three isolates produced protease, non-haemolysin-producing strain and sensitive to Gentamicin or Kanamycin but resistant to Ampicillin, Tetracycline and Chloramphenicol. Those three isolates were identified based on homology of 16S rDNA sequence. Strain 1-1 and 1-16 were identified as P. aeruginosa, while Strain 6-10 identified as Sa marcescens.
Conclusion, Significance and impact of study: This finding was showed the potential endophytic bacteria from Indonesian mangrove plants with antibacterial and enzyme production.
of their safety. Microorganisms are interesting for pigment production and many of them have been used in food industry. Many research have been conducted to find out for natural pigment sources. The objective of this research was to investigate the characteristics of a red-pigmented bacteria isolated from Gedong Songo hot spring, Bandungan-Indonesia.
Methodology and results: Bacterial isolates were grown on Nutrient Agar for 24 h, and the morphology of the colonies and of the cells were identified. Biochemical tests included indole, methyl red, catalase, urease tests and carbohydrate fermentation. Molecular identification was based on 16S rRNA sequence. The isolate was a rod shape and Gram-negative. Biochemical tests showed that the isolate was indole negative, catalase positive, methyl red negative and urease negative. This isolate was glucose, maltose and sucrose positive and negative for lactose. 16S rRNA sequence was BLAST and it matched with Serratia marcescens strain S823. The red pigment antioxidant activity showed the highest DPPH radical scavenging of 49.11% obtained from 48 h of incubation. Functional group of S. marcescens pigment on Fourier Transform InfraRed Spectroscopy (FTIR) displayed specific peak at 1740 cm-1 represented of C═O (carbonyl) stretching group.
Conclusion, significant and impact of study: Based on morphological, biochemical and moleculer identifications, it showed that the bacteria isolated from Gedong Songo hot spring Bandungan-Indonesia had 94% homology with Serratia marcescens strain S823. Based on DPPH radical scavenging test, it demonstrated that S. marcescens had potency as an antioxidant.
Aims: Preterm premature rupture of membrane (PPROM) is usually associated with maternal vaginal colonization of Group B Streptococci (GBS). However, there are reports on isolation of Acinetobacter baumannii in PPROM cases. In order to ascertain A. baumannii’s role in PPROM, we determine the colonization of A. baumannii and other common vaginal tract flora, i.e. GBS and Candida albicans, in women with PPROM, and compared them to those with normal labor at term (NLT). The transmissibility of the organisms to their babies was also investigated.
Methodology and results: A total of 218 high vaginal swabs from 108 and 100 women with PPROM and NLT respectively were collected. The transmission of these organisms to their 215 babies was determined by swabbing the ears and axillae. These were cultured for isolation of A. baumannii, GBS and C. albicans. Results showed that mothers with PPROM were predominantly colonized with GBS (32.4%), followed by C. albicans (19.4%) and A. baumannii (7.4%), compared to 10.9%, 17.3% and 7.2% respectively, in women with NLT. Between 34 to 50% of the babies of mothers with PPROM acquired the organisms, with GBS being the most significantly (p=0.000) transferred compared to other organisms. Co-existence of A. baumannii with either GBS or C. albicans, or both, did not enhance the occurrence of PPROM.
Conclusion, significance and impact of study: Colonization of A. baumannii in vaginal tract of pregnant women does not increase the possibility of PPROM, as compared to GBS.
Aims: Oleaginous yeasts are widely used for the production of biodiesel feedstocks because of their high lipid content. This research was aimed to conduct random mutagenesis of Rhodotorula mucilaginosa using ethyl methane sulfonate (EMS) and identify the mutants with improved lipid production.
Methodology and results: A total of twenty-two mutant isolates prescreened with cerulenin were produced and further characterized via M13 PCR fingerprinting to determine their polymorphism and genetic distances. Eight strains, namely M1, M2, M3, M4, M7, M10, M11 and M18, were chosen based on their genetic distances from the parental strain for biomass production. Six mutants (M1, M2, M3, M4, M7 and M18) showing the highest dry cell weights were further selected for evaluation of lipid production in a laboratory-scale bioreactor using glucose as a carbon source. Results indicated that parental strain exhibited lipid content of 1.83 g/L, while strains M1, M2, M3, M7 and M18 generated 2.37 g/L, 2.27 g/L, 2.27 g/L, 3.10 g/L and 3.83 g/L of intracellular lipid, respectively. These five mutants were identified to have significant increase in lipid production compared to the parental strain.
Conclusion, significance and impact of study: This study demonstrated enhanced lipid production in R. mucilaginosa by random mutagenesis. New generated strains had higher lipid productivity compared to parental strain and application of these strains in industry may reduce the overall cost of biodiesel production.
Aims: Hyaluronic acid (HA) is a high molecular weight polymer and a major component of mucoid capsule in bacteria and extracellular matrix (ECM) of vertebrate tissue. Due to its unique characteristics, HA is used extensively in medical and cosmetic field. However, because of the exotoxins production from animal tissues extraction and Streptococcus zooepidemicus, HA production by recombinant microorganisms has gained interest. The present study was aimed at cloning of hasA gene in Escherichia coli and optimization of the medium components for HA production.
Methodology and results: A fragment of an approximate size of 1.5kb that encodes the hyaluronan synthase (hasA) gene from S. zooepidemicus ATCC 39920 was amplified by PCR using hasA-specific primers. The hasA gene was ligated into the bacterial expression vector pLbADH and transformed into the expression host, Escherichia coli BL21 strain. Then, genetically engineered E. coli strain BL21 was used for the production of HA by fermentation using different glucose concentration (10-50 g/L) and different IPTG concentration (0.1, 0.5 and 1.0 mM) in shake flask culture. Amongst varying glucose concentrations, results showed that 50 g/L glucose with nutrient rich media containing nitrogen source was able to produce the highest HA concentration (0.115 ± 0.002 g/L). With addition of 1.0 mM IPTG, HA production reached a peak 0.532 ± 0.026 g/L which is around fivefold higher compared to without IPTG.
Conclusion, significance and impact of study: The hasA gene was cloned from S. zooepidemicus and successfully expressed in recombinant E. coli BL21 cells. This low molecular weight HA is gaining more importance in medical and cosmetic application due to possess pronounced free radical scavenging and antioxidant activities.