Biology subjects

Vijay Kothari

Publications and source records attributed to Vijay Kothari.

3 recordsLinked to original sources

bioRxiv2016

Quorum sensing modulatory effect of sound stimulation on Serratia marcescens and Pseudomonas aeruginosa

Effect of nine different mono-frequency sound stimuli on two gram-negative bacteria (Pseudomonas aeruginosa and Serratia marcescens) was investigated. Frequency of the test sound ranged from 100 Hz to 2,000 Hz. Both the test bacteria responded differently to sonic stimulation. Sound corresponding to 600 HZ caused a notable reduction in quorum sensing (QS) regulated production of the pigment pyoverdine by P. aeruginosa. 400 Hz sound affected prodigiosin production by S. marcescens the most. 500 Hz sound could enhance prodigiosin production without affecting growth of the producing bacterium, suggesting the effect purely to be QS modulatory. This study has demonstrated the capacity of the sound waves of affecting bacterial growth and quorum sensing regulated metabolite production.

Microbiology↗

bioRxiv2016

Influence of a mono-frequency sound on bacteria can be a function of the sound-level

Chromobacterium violaceum was subjected to sonic stimulation with 300 Hz sound, at five different levels of loudness in the range of 70 - 89.5 dB. Sonic stimulation was found to affect bacterial growth and quorum sensing regulated pigment (violacein) production significantly. Magnitude of this effect was found to be dependent on sound-level. The minimum critical difference required to cause any statistically significant change in bacterial response with respect to sound-level was found to be 13 dB. Growth of C. violaceum was affected more at lower sound intensity, whereas pigment production was affected more at higher sound intensity. Additional experiments with C. violaceum and Serratia marcescens indicated that even a silent speaker emitting no sound can alter bacterial growth and/or pigment production upto a minor extent. Size of the test tube in which bacteria are exposed to sonic stimulation, was not found to affect the results much.

Microbiology↗

bioRxiv2016

MICROWAVE MUTAGENESIS OF BREVIBACILLUS PARABREVIS FOR ENHANCED CELLULASE PRODUCTION, AND INVESTIGATION ON THERMOSTABILITY OF THIS CELLULASE

Microwave mutagenesis of Brevibacillus parabrevis for enhanced cellulase production was attempted. Though microwave treatment could alter the cellulase activity of the test bacterium, none of the mutants obtained were found to be genetically stable, indicating the reversible nature of microwave-induced mutation(s). Thermal stability of the B. parabrevis cellulase was also investigated. This enzyme was found to be capable of retaining its activity even after heat treatment (50-121{degrees}C, for 30-60 min). Fluorescence spectrum revealed a red shift in the emission maxima of the heat-treated enzyme preparations, indicating some structural change upon heating, but no major loss of activity was observed. This enzyme was found to be active over a broad temp range, with 90{degrees}C as the optimum temp, which is interesting as the producing organism is a mesophile.

Microbiology↗