Production of 10-hydroxy-12,15(Z,Z)-octadecadienoic acid from α-linolenic acid by permeabilized Stenotrophomonas nitritireducens cells

Production of 7,10-dihydroxy-8(E)-octadecenoic acid using cell-free supernatant of Pseudomonas aeruginosa

Cell-free synthesis has been adopted in the bioconversion process due to its known advantages, such as fast production rate, high product content, and no substrate/product inhibition effect. In this study, the cell-free supernatant of Pseudomonas aeruginosa was used to improve the production of 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) from oleic acid. DOD production using cell-free supernatant demonstrated reduction in bioconversion duration and higher product concentration than conventional method using whole cell culture. The maximum DOD concentration (6.41 g/L) was obtained after 36 h of biotransformation using 1 % v/v oleic acid as a substrate with a productivity of 0.178 g/L/h and a yield of 74.8 %. DOD concentration, productivity, and yield using cell-free supernatant were 2.12, 7.12, and 2.22 times higher, respectively, than using the conventional whole cell culture method. Of the carbon and nitrogen sources used in pre-culture, galactose and sodium glutamate along with diammonium phosphate were found to be the most effective for DOD production. An incubation temperature of 27 °C and pH 8.0 were found to be most favorable for DOD production. In addition, sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis demonstrated the presence of enzymes related to DOD production in the cell-free supernatant, which was substantiated by performing DOD production experiment using the supernatant enzymes extracted from protein gel bands with oleic acid as a substrate. To the best of our knowledge, this is the first report on DOD production using a cell-free supernatant and verifying the existence of the relevant enzymes in the cell-free supernatant. Compared to whole cell process, cell-free DOD production holds several advantages, including higher DOD productivity which could be beneficial for large-scale production.

An integrative approach to improving the biocatalytic reactions of whole cells expressing recombinant enzymes

Biotransformation is a selective, stereospecific, efficient, and environment friendly method, compared to chemical synthesis, and a feasible tool for industrial and pharmaceutical applications. The design of biocatalysts using enzyme engineering and metabolic engineering tools has been widely reviewed. However, less importance has been given to the biocatalytic reaction of whole cells expressing recombinant enzymes. Along with the remarkable development of biotechnology tools, a variety of techniques have been applied to improve the biocatalytic reaction of whole cell biotransformation. In this review, techniques related to the biocatalytic reaction are examined, reorganized, and summarized via an integrative approach. Moreover, equilibrium-shifted biotransformation is reviewed for the first time.

Complete Biotransformation of Protopanaxadiol-Type Ginsenosides into 20-O-β-Glucopyranosyl-20(S)-protopanaxadiol by Permeabilized Recombinant Escherichia coli Cells Coexpressing β-Glucosidase and Chaperone Genes

The ginsenoside 20-O-β-glucopyranosyl-20(S)-protopanaxadiol or compound K is an essential ingredient in functional food, cosmetics, and traditional medicines. However, no study has reported the complete conversion of all protopanaxadiol (PPD)-type ginsenosides from ginseng extract into compound K using whole-cell conversion. To increase the production of compound K from ginseng extract using whole recombinant cells, the β-glucosidase enzyme from Caldicellulosiruptor bescii was coexpressed with a chaperone expression system (pGro7), and the cells expressing the coexpression system were permeabilized with ethylenediaminetetraacetic acid. The permeabilized cells carrying the chaperone coexpression system showed a 2.6-fold increase in productivity and yield as compared with nontreated cells, and completely converted all PPD-type ginsenosides from ginseng root extract into compound K with the highest productivity among the results reported so far. Our results will contribute to the industrial biological production of compound K.

Complete genome sequence of Stenotrophomonas sp. KACC 91585, an efficient bacterium for unsaturated fatty acid hydration

Hydroxy fatty acids (HFAs) such as 10-hydroxystearic acid (10-HSA) and 10-hydroxy-12(Z)-octadecenoic acid (10-HOD), which are similar to ricinoleic acid, are important starting materials and intermediates for the industrial manufacture of many commodities. Stenotrophomonas sp. KACC 91585, which was isolated from lake sediment, is an efficient bacterium for unsaturated fatty acid hydration that produces 10-HSA and 10-HOD from oleic acid and linoleic acid, respectively, with high conversion rates. The complete genome of this strain is 4,541,729bp with 63.83% GC content and devoid of plasmids. Sets of genes involved in the fatty acid biosynthesis and modification as well as modified lipids were identified in the genome, and these genes were concerned with HFA production. This genome sequence provides molecular information and elucidation for HFA production, and will be used as an efficient biocatalyst source for the biotechnological production of HFA.

D-Allulose Production from D-Fructose by Permeabilized Recombinant Cells of Corynebacterium glutamicum Cells Expressing D-Allulose 3-Epimerase Flavonifractor plautii

A d-allulose 3-epimerase from Flavonifractor plautii was cloned and expressed in Escherichia coli and Corynebacterium glutamicum. The maximum activity of the enzyme purified from recombinant E. coli cells was observed at pH 7.0, 65°C, and 1 mM Co²⁺ with a half-life of 40 min at 65°C, K_m of 162 mM, and k_cat of 25280 1/s. For increased d-allulose production, recombinant C. glutamicum cells were permeabilized via combined treatments with 20 mg/L penicillin and 10% (v/v) toluene. Under optimized conditions, 10 g/L permeabilized cells produced 235 g/L d-allulose from 750 g/L d-fructose after 40 min, with a conversion rate of 31% (w/w) and volumetric productivity of 353 g/L/h, which were 1.4- and 2.1-fold higher than those obtained for nonpermeabilized cells, respectively.