Low-Intensity Ultrasound Effect on Bacillus subtilis Biomass and Metabolite Synthesis

Abstract

This study set out to see if using 33 Khz ultrasonic frequency for Bacillus subtilis increases biomass and metabolite synthesis. Increased oxygen and nutrient delivery to cells is assumed to be the cause of the rise in biomass on surfaces and in suspension. Although ultrasonic loss of cells is undesirable, some cell removal or death may be tolerated if the accelerated rate of cell growth exceeds the rate of cell removal. Bacillus sp. was selected as the test isolates because members of this gram-positive genus are known to be industrially relevant bacteria. Ultrasound was used to accelerate growth of Bacillus subtilis cells. When compared to growth without ultrasound, low-frequency ultrasound (33 kHz) was found to accelerate cell development. Ultrasonic exposure over a shorter amount of time (up to 30 min) not only increased planktonic development of the bacterial cells, but also increased protease synthesis to 121.5 g/mL from 95 g/mL. (60 min). It is believed to promote cell growth by improving the transport of oxygen, nutrients, and waste materials within and out of cells.