Glycerol bioconversion in unconventional magnetically assisted bioreactor seeking whole cell biocatalyst (intracellular lipase) production

Low frequency magnetic field assisted production of acidic protease by Aspergillus niger

Acid protease is widely used in industries such as food processing and feed additives. In the study, low frequency magnetic field (LF-MF) as an aid enhances acid protease production by Aspergillus niger (A. niger). The study assessed mycelial biomass, the enzymic activity of the acidic protease and underlying mechanism. At low intensities, alternating magnetic field (AMF) is more effective than static magnetic fields (SMF). Under optimal magnetic field conditions, acid protease activity and biomass increased by 91.44% and 16.31%, as compared with the control, respectively. Maximum 19.87% increase in enzyme activity after magnetic field treatment of crude enzyme solution in control group. Transcriptomics analyses showed that low frequency alternating magnetic field (LF-AMF) treatment significantly upregulated genes related to hydrolases and cell growth. Our results showed that low-frequency magnetic fields can enhance the acid protease production ability of A. niger, and the effect of AMF is better at low intensities. The results revealed that the effect of magnetic field on the metabolic mechanism of A. niger and provided a reference for magnetic field-assisted fermentation of A. niger.

Improving microbial production of value-added products through the intervention of magnetic fields

The magnetic field application is emerging as an auxiliary physical strategy to facilitate rapid biomass accumulation and intracellular production of compounds. However, the underlying mechanisms and principles governing the application of magnetic fields for microbial growth and biotransformation are not yet fully understood. Therefore, a better understanding of interdisciplinary technologies integration, expanded magnetic field application, and scaled-up industrial implementation is crucial. In this review, the magnetic field characteristics, magnetic field-assisted fermentation devices, and the working mechanism of magnetic field have been reviewed comprehensively from both physical and microbiological perspectives. The review suggests that magnetic fields affect the biochemical processes in microorganisms by mediating nutrient transport across membranes, electron transfer during photosynthesis and respiration, enzyme activity and gene expression. Moreover, the recent advances in magnetic field application for microbial fermentation and conversion in biochemical, food and agricultural fields have been summarized.

Extracellular lipase production by Yarrowia lipolytica under magnetic fields

This study aimed at estimating cultivation conditions to enable Yarrowia lipolytica NNRL Y-1095 to produce extracellular lipase and at evaluating the influence of magnetic fields (MF) on the lipase production and on its catalytic conditions. Culture conditions of carbon sources and surfactant defined to produce extracellular lipase were 10 g L-1 glucose, 15 g L-1 olive oil and 2 g L-1 Triton X-100. The highest lipase activity (34.8 U mL-1) was reached after 144 h when MFs were applied from 72 to 144 h of culture. It corresponds to an increase of 287.5% by comparison with the highest lipase activity in the control culture. MF application from 72 to 144 h did not change the optimal temperature of lipase, which was 37 °C, by comparison with the control. However, the optimal pH of the control was 7.0 while the one of lipase produced with MF was 8.0. Findings highlighted that the presence of MFs led to increase in synthesis of lipase by Y. lipolytica, with changes in the catalytic profile. This is one of the first studies of MF application to Y. lipolytica NRRL Y-1095 cultures to produce lipase.

An overview on the conversion of glycerol to value-added industrial products via chemical and biochemical routes

Glycerol is a common by-product of industrial biodiesel syntheses. Due to its properties, availability, and versatility, residual glycerol can be used as a raw material in the production of high value-added industrial inputs and outputs. In particular, products like hydrogen, propylene glycol, acrolein, epichlorohydrin, dioxalane and dioxane, glycerol carbonate, n-butanol, citric acid, ethanol, butanol, propionic acid, (mono-, di-, and triacylglycerols), cynamoil esters, glycerol acetate, benzoic acid, and other applications. In this context, the present study presents a critical evaluation of the innovative technologies based on the use of residual glycerol in different industries, including the pharmaceutical, textile, food, cosmetic, and energy sectors. Chemical and biochemical catalysts in the transformation of residual glycerol are explored, along with the factors to be considered regarding the choice of catalyst route used in the conversion process, aiming at improving the production of these industrial products.

On the performance of immobilized cell bioreactors utilizing a magnetic field

This review focuses on the performance of immobilized cell bioreactors utilizing a magnetic field. These reactors utilized immobilized cells on magnetic particles or beads as the solid phase. All published research papers dealing with the performance of immobilized cell bioreactors utilizing a magnetic field from the early 1960s to the present time were considered and analyzed. It was noted that many microorganisms such as Saccharomyces cerevisiae were immobilized on different supports in these reactors. These papers used the magnetic field for several purposes, mainly for the stabilization of magnetic particles to prevent their washout from the column while operating with relatively high substrate flow rates to enhance mass transfer processes. It was observed that most publications used an axial magnetic field. In addition, most of the magnetic particles were prepared by entrapment. Some comments are presented at the end of the review which show the gaps in this promising application.