Ultrasonic intensification as a tool for enhanced microbial biofuel yields

Abstract

Ultrasonication has recently received attention as a novel bioprocessing tool for process intensification in many areas of downstream processing. Ultrasonic intensification (periodic ultrasonic treatment during the fermentation process) can result in a more effective homogenization of biomass and faster energy and mass transfer to biomass over short time periods which can result in enhanced microbial growth. Ultrasonic intensification can allow the rapid selective extraction of specific biomass components and can enhance product yields which can be of economic benefit. This review focuses on the role of ultrasonication in the extraction and yield enhancement of compounds from various microbial sources, specifically algal and cyanobacterial biomass with a focus on the production of biofuels. The operating principles associated with the process of ultrasonication and the influence of various operating conditions including ultrasonic frequency, power intensity, ultrasonic duration, reactor designs and kinetics applied for ultrasonic intensification are also described.

Effects of ultrasound on submerged fermentation for producing antioxidant metabolites from Botryosphaeria dothidea

“…After the stimulus, it returns to its steady-state. Intermittent applications of ultrasound have been evaluated (Naveena et al 2015) to increase the rate of sugar consumption and to improve the production of metabolites. However, intermittent applications can cause the lysis of the cells or the formation of free radicals.…”

“…The treatment with ultrasound can increase the release of desired substances (Liu et al 2012 ranging from 10 to 100 kHz), low-intensity ultrasound (< 1 W cm −2 and frequencies ranging from 1 to 10 MHz) does not destroy the microorganism because the sound waves permeate the liquid medium, causing no permanent physical or chemical changes (Naveena et al 2015;Yao et al 2014). Sun et al (2017), Yao et al (2014), and Wang et al (2013) evaluated the fungi Shiraia bambusicola, Aspergillus fumigatus and Trametes versicolor, respectively, for the production of antioxidant enzymes and compounds based on low-intensity ultrasound (< 2 W cm −2 ) and low frequency (< 100 kHz).…”

Sonochemistry: Applications in Biotechnology

“…Ultrasonic intensification (periodic ultrasonic treatment during the fermentation process) can result in a more effective homogenization of biomass and faster energy and mass transfer to biomass over short time periods which can result in enhanced microbial growth. Ultrasonic intensification can allow the rapid selective extraction of specific biomass components and can enhance product yields which can be of economic benefit [24]. During lipid extraction from biomass, the physical effects of ultrasonication Sonochemistry: Applications in Biotechnology DOI: http://dx.doi.org/10.5772/intechopen.88973 can significantly enhance the lipid yield.…”

“…Micro-turbulence can lead to a more efficient mixing of the biomass and solvent (without induction of shear stress), while shock waves can cause rupture of the cell wall. Ultrasound can also generate intense local turbulence in the medium, pushing the extracted lipids away from the surface of the microbial cells, and thus, maintaining a constant concentration gradient for continuous diffusion of lipids from the cells [24] (Figure 19).…”

Acoustofluidic harvesting of microalgae on a single chip

“…1,8 For harvesting such microalgae from environmental samples, cultivation ponds, or photobioreactors, methods for sampling, isolating, and purifying target microalgae and their unique strains are of prominent importance, but are required to overcome a number of technical challenges before they can be broadly deployed in the competitive fuel market. 9,10 Unfortunately, conventional harvesting methods are not cost-effective as they involve timeand energy-consuming procedures such as filtration, chemical flocculation, centrifugation, and a combination of any of these before drying. 11,12 Since nearly 30% of the total biofuel production a) sangwook_l@chem.s.u-tokyo.ac.jp b) goda@chem.s.u-tokyo.ac.jp…”