1.Bioprospecting of Endophytic Fungi as Promising Anti-MRSA Agents
Yee-Min WEI ; Joo-Shun TAN ; Hock-Wei TANG ; Woei-Yenn TONG ; Chean-Ring LEONG ; Wen-Nee TAN
Natural Product Sciences 2022;28(3):93-104
Methicillin-resistant Staphylococcus aureus (MRSA) is a serious threat to the global healthcare system. Ineffective and resistance to antibiotic treatments have increased morbidity and mortality rates worldwide.New and effective antibiotics are needed to combat against bacterial resistance. Endophytic fungi are crucial reservoirs of novel bioactive metabolites. In particular, the secondary metabolites show promising therapeutic potential, notably, antibacterial. This review discussed the emerging potential of endophytic fungi as anti-MRSA agents. The ecological sources of endophytic fungi were discussed with the synthesis of bioactive metabolites.The mode of antibacterial actions was elucidated to give a better understanding of the mechanisms involved. This review may serve as an important reference for future discovery and developments of anti-MRSA agents from endophytic fungi.
2.Optimization of polyhydroxyalkanoate (PHA) production by Burkholderia cepacia BPT1213 utilizing waste glycerol as the sole carbon source
Nor Fauziah Mohd Zain ; Wan Nadiah Wan Abdullah ; Tan Joo SHUN ; Lee Chee KEONG ; Mohammed Razip SAMIAN
Malaysian Journal of Microbiology 2018;14(2):164-171
Aims:This study was carried out to optimize the fermentation conditions using statistical approach for polyhydroxyalkanoate(PHA) production by a local isolate, Burkholderia cepaciaBPT1213, in the shake flask system.Methodology and results:Throughout this study, B. cepaciaBPT1213 was grown in minimal salt medium (MSM) supplemented with 2% of waste glycerol (86.70% purity).The strain can produce up to 1.33 g/L cell dry weight (CDW) with 22.21% of PHA content, thus giving a total PHA concentration 0.30 g/L before optimization. A factorial design experiment that was carried out showed all parameters KH2PO4, Na2HPO4·2H2O, carbon-to-nitrogen ratio (C/N), initial pH of medium, and temperature significantly affected the growth (cell dry weight, CDW) and PHA content. Response surface methodology (RSM) using central composite design (CCD) was then applied to optimize these parameters. The optimum conditions suggested were at 2.5 g/L KH2PO4, 4.5 g/L Na2HPO4·2H2O, 30 (g/g) C/N ratio, initial medium pH of 8.5 and 37 °C cultivation temperature, with a predicted CDW of 3.43 g/L and PHA content of 45.71% contributing to 1.57 g/L total PHA concentration. The verification experiment resulted in 3.60 g/L of CDW with 48.08% of PHA content contributing to 1.73 g/L total PHA concentration.Conclusion, significance and impact of study:The statistical approach using factorial design and RSM have succeeded in increasing the production of PHA by B. cepaciaBPT1213 using waste glycerol as the sole carbon source which is a promising renewable and cheaper feedsto
3.Biosynthesis of lipase by Burkholderia cenocepacia ST8 using waste cooking oil as feedstock
Ellie Ai Li Keong ; Joo Shun Tan ; Zee Wei Lai
Malaysian Journal of Microbiology 2021;17(3):277-285
Aims:
Every year, an estimated 25 million tons of waste oil are produced worldwide, and the generation of waste oil is
one of the biggest global environmental problems. The incorporation of oil as a substrate for lipase production has
been studied and shown to have a positive impact on its production. Burkholderia sp. is one of the major lipase-producing bacteria with their ability in bioremediation of oil-contaminated soil. This study aims to compare the
production of lipase by Burkholderia cenocepacia ST8 using waste cooking oil and unused cooking oil as feedstock.
Methodology and results:
The effect of different types of waste cooking oil (sunflower oil and palm oil) and
concentration (1-3%) of waste cooking oil, agitation speed (100-400 rpm) and initial dissolved oxygen concentration
(10-50%) on lipase production by B. cenocepacia ST8 under batch fermentation mode were investigated. The major
fatty acids of which had been consumed were determined using gas chromatography. Results showed that 2% (v/v) of
single used sunflower cooking oil produced the highest lipase activity of 138.86 U/mL with a productivity of 2.10
U/mL/h; agitation speed of 300 rpm produced the highest lipase activity of 183.56 U/mL with a productivity of 3.06
U/mL/h while 30% initial concentration of dissolved oxygen produced a lipase activity of 176.45 U/mL with a
productivity of 2.94 U/mL/h. Oleic acid and linoleic acid were found to be the most consumed by B. cenocepacia ST8
among other fatty acids.
Conclusion, significance and impact of study
This study shows that 2% (v/v) single used sunflower cooking oil
was the better type and optimum concentration of carbon source for the production of lipase by the fermentation of B.
cenocepacia under 300 rpm and 30% initial concentration dissolved oxygen. The incorporation of 2% (v/v) single used
sunflower cooking oil may be a great alternative to reduce the cost for the production of lipase as well as reducing the
amount of waste oil generation.
Lipase
;
Burkholderia cenocepacia
;
Waste Management
;
Biodegradation, Environmental
4.Isolation and characterization of Lactobacillus brevis C23 with ability to secrete antimicrobial substance for the inhibition of a foodborne pathogen Listeria monocytogenes ATCC 7644
Dharni Kuhan Sreedharan ; Sahar Abbasiliasi ; Paramasivam Murugan ; Zhang Jin Ng ; Arbakariya Bin Ariff ; Joo Shun Tan
Malaysian Journal of Microbiology 2021;17(3):266-276
Aims:
This study aims to isolate lactic acid bacteria (LAB) from various food sources to obtain a potent strain against Listeria monocytogenes.
Methodology and results:
A total of 68 LAB isolates were selected to evaluate their antimicrobial activity against L.
monocytogenes, a foodborne pathogen and a causative agent of listeriosis. The selected isolate was identified and
characterized. The isolate C23 from cabbage showed the highest antimicrobial activity against L. monocytogenes ATCC
7644 with inhibition ability of 73.94%. The isolate was closely related to Lactobacillus brevis by 16S rRNA sequencing
and subsequently deposited in GenBank with an accession number of MN880215, named as L. brevis C23. The cell free
supernatant (CFS) of L. brevis C23 had high tolerance in low pH and was able to withstand up to 60 °C. The
proteinaceous nature of the antimicrobial agent was also confirmed through the enzymatic test. The CFS was stable on
different detergents as well as bile salts. Under transmission electron microscopy (TEM), the inhibitory effect of CFS
against L. monocytogenes was proven by causing cell lysis.
Conclusion, significance and impact of study
Bacteriocin-like inhibitory substances (BLIS) of L. brevis C23 showed
very promising potential in food industrial application.
Lactobacillales
;
Listeria monocytogenes
;
Foodborne Diseases
;
Sprains and Strains