In silico structural exploration of serine protease from a CTG-clade yeast Meyerozyma guilliermondii strain SO.

In eukaryotes, serine proteases are cellular localized hydrolases reported to regulate essential biological reactions. Improved industrial applications of proteins are aided by prediction and analysis of their 3-dimensional structures (3D). A serine protease was identified from CTG-clade yeast Meyerozyma guilliermondii strain SO and its 3D structure as well as its catalytic attributes have not been fully understood yet, thus we seek to report on the catalytic mechanism of M. guilliermondii strain SO MgPRB1 using substrate PMSF via in silico docking as well as its stability by way of disulfide bonds formation. Herein, bioinformatics tools and techniques were used to predict, validate and analyze the possible changes of CUG ambiguity (if any) in strain SO using template PDB ID: 3F7O. Structural assessments confirmed the classic catalytic triad Asp305, His337, and Ser499. Superimposition of MgPRB1 and template 3F7O structures revealed the unlinked cysteine residues between Cys341, Cys440, Cys471 and Cys506 of MgPRB1 compared to template 3F7O with two disulfide bonds formation, which confers structural stability. In conclusion, serine protease structure from strain SO was successfully predicted and studies towards understanding at the molecular level may be undertaken for its potential applications in the degradation of peptide bonds.

Biosynthesis of lipase by Burkholderia cenocepacia ST8 using waste cooking oil as feedstock

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.

Isolation and characterization of Lactobacillus brevis C23 with ability to secrete antimicrobial substance for the inhibition of a foodborne pathogen Listeria monocytogenes ATCC 7644

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.