Table 2.

Application of ultrasound technology for the production or activation of various microbial metabolites and functions.

Metabolite/Activity	Processing Conditions	Salient Findings	References
β-1.3(1.6)-Glucan schizophyllan (SPG)	20 kHz, 2000 W, 100% amplitude	High purity SPG having immunomodulatory activity	[80]
Ethanol production	24 kHz, 60% amplitude	Inducing enzymatic hydrolysis of sugar/maximum yield of 90% ethanol	[81]
Bioethanol production	40 kHz, 5 min, 60 °C	Accelerated the starch hydrolysis, degradation of starch granules and release of glucose, Increase the ethanol concentration by 11.15%	[82]
Bioethanol	1.8 Wcm−2 20% duty cycle	Enhanced the extracellular and the intracellular levels of β-galactosidase Ethanol concentration of 5.20 ± 0.68 g L−1	[83]
Sludge activity	35 kHz, 0.2 W/cm2, 10 min	Enhanced biological removing the chemical oxygen demand (COD)	[84]
Saponins of ginseng cells	≤0.1 W/cm3, 38.5 kHz	Increased cross-membrane ion fluxes (Ca2+ influx and K+ efflux/H+ influx) Production of active oxygen species, Stimulation of useful secondary metabolites synthesis	[30]
Sophorolipid biosurfactants	40 kHz, 600 W, 10 min at duty cycle of 20%	Increased sophorolipid production by 193%	[63]
Biosurfactant	25 kHz, 7.4 W, 30 min	Increased biomass and biosurfactant production by 1.3 times	[85]
Rhamnolipid biosurfactant	150 W, 6 min, 42.5% duty cycle	Enhanced the yield of rhamnolipid 1.5 folds	[86]
Fibrinolytic enzyme	25 kHz, 160 W, 20% duty cycle for 5 min	Improving substrate intake and metabolism of microbial cell Increased productivity of fibrinolytic enzyme by 1.82-fold	[87]
Galactooligosaccharide enzyme	30% amplitude, 30 W	high yield of galactooligosaccharide production	[88]
Lactoperoxidase purification	Intermittent 35 kHz and 250 rpm, 25 ± 2 °C	Purification of lactoperoxidase by coupling aqueous two-phase extraction Increasing in flux	[89]
Fermentation profile of Lactobacillus sakei	Low power ultrasound (2.99 W) for 5 min	Higher specific growth rate (µ) and shorter lag phase Antimicrobial activity of Cell-free extracts against pathogenic bacteria	[90]
Apple juice fermentation	Pulse duration 0.5 s and 6 s rest period	Increase in biomass growth and glucose consumption	[91]