Purification and characterization of a Bacillus subtilis keratinase and its prospective application in feed industry

We have isolated a Bacillus subtilis strain (RSE163) from soil and explored for keratinase production. Keratinase was purified using chromatographic methods (Sephadex G-75 and Q Sepharose) resulting in 8.42-fold purification with 3303 U/mg specific activity.The purified enzyme displayed 3 bands in close proximity between 20 to 22 kDa in SDS-PAGE which were apparent to the zone of hydrolysis in gelatin zymogram. Enzyme was stable over a wide pH (7.0-10.0) and temperature (30 °C to 70 °C) range with optimum activity at pH 9.0 and 60 °C. Keratinase activity was stimulated in presence of Mn2+, β-mercaptoethanol and surfactants (Triton-X and Tween-80) and inhibited by Fe3+, Cd2+, K+, PMSF (phenyl methane sulfonyl fluoride) and other chelating and reducing agents. The enzyme efficiently hydrolyzed a variety of complex protein substrates (chicken feather, keratin hydrolyzate and casein) and enzyme kinetics parameters were determined using Lineweaver Burk plot (Km = 6.6 mg/ml, Vmax = 5 U/ml/min). Hydrolyzed feather keratin obtained through fermentation with B. subtilis RSE163 has been explored for its cytotoxicity using liver cell line (HepG2). No cytotoxicity has been determined up to 0.015% concentration of hydrolyzed product indicating its potential applicability as feed supplement

Effect of one-day training on Knowledge related to Biosafety and waste management among life-science Students

Context: Laboratory workers are at increased risk of occupational hazards especially microbial infections. These occupational hazards can be reduced by merely creating awareness related to Biosafety. Thus biosafety and waste management training is important and needs to be inculcated at novice stage. Aims: The present study aimed to assess the effect of one-day training program on knowledge related to biosafety and biohazard among life-science students. Settings and Design: The study was conducted through online medium, organized by Department of Microbiology, Institute of Home Economics, University of Delhi using a Quasi Experimental design. Methods and Material: A one-day training on Biosafety and Waste Management was organized by Department of Microbiology for life-science students. A pre-test with 15 questions was administered to the participants before commencement of the training. One mark was allotted for each correct response and zero marks for incorrect marks. At the end of training, post knowledge was assessed using the same questions as pre-test. Statistical analysis used: The data on pre-post knowledge assessment was analyzed using SPSS Version 21. Paired t-test was used to assess the mean difference in pre and post knowledge assessment amongst the participants. The level of significance was taken as <0.05. Results: A total of 81 participants was analyzed for pre-post analysis. The mean age was 19.98 ± 1.06 years with 59(72.8%) being females. The mean pre-knowledge and post-knowledge score was found to be 10.20 ± 2.09 and 14.02 ± 1.63 respectively. The mean difference of 3.83 ± 2.23 in pre and post knowledge was found to be significant (p<0.001). Conclusions: Life-science students have poor-to-moderate knowledge about biosafety and waste management. Training on biosafety helps in improving knowledge

Comparative transcriptome analysis of arsenate and arsenite stresses in rice seedlings

The effect of arsenic (As) exposure on genome-wide expression was examined in rice (Oryza sativa L., ssp. Indica). A group of defense and stress-responsive genes, transporters, heat-shock proteins, metallothioneins, sulfate-metabolizing proteins, and regulatory genes showed differential expression in rice seedlings challenged with arsenate (AsV) and arsenite (AsIII). AsV stress led to upregulation or downregulation of an additional set of genes in comparison to AsIII. Differential expression of several genes that showed the highest contrast in a microarray analysis was validated by following the quantitative changes in the levels of individual transcripts following challenge with AsV, AsIII, Cd, Cr, and Pb. Most of the selected genes responded to challenge by heavy metals such as arsenic. However, expression of one of the cytochrome P450 genes (Os01g43740) in rice root was induced by AsV but not by other heavy metals. Similarly, one glutaredoxin (Os01g26912) is expressed specifically in the AsIII-treated shoot