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Angiotensin-converting enzyme 2 (ACE2) is a binding target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. An ACE2-like enzyme, such as bacterial M32-carboxypeptidase (M32-CAP), is assumed to be a potential therapeutic candidate for coronavirus disease 2019 (COVID-19). Here, we screened bacteria with an ACE2-like enzyme activity from Japanese fermented food and dietary products using the fluorogenic substrate for rapid screening. The strain showing the highest activity, Enterobacter sp. 200527-13, produced an enzyme with the same hydrolytic activity as ACE2 on Angiotensin II (Ang II). The enzymatic analysis using the heterologously-expressed enzyme in Escherichia coli revealed that the enzyme catalyzes the same reaction with that of ACE2, Ang II hydrolysis to Ang 1-7, and phenylalanine. The gene sequence information showed that the enzyme belongs to the M32-CAP family. These results suggested that the selected enzyme, M32-CAP (EntCP), from Enterobacter sp. 200527-13 was identified as an ACE2-like enzyme., (© The Author(s) 2023. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

S-Allyl-l-cysteine (SAC) has received much interest due to its beneficial effects on human health. To satisfy the increasing demand for SAC, this study aims to develop a valuable culturing method for microbial screening synthesizing SAC from readily available materials. Although tryptophan synthase is a promising enzyme for SAC synthesis, its expression in microorganisms is strictly regulated by environmental l-tryptophan. Thus, we constructed a semisynthetic medium lacking l-tryptophan using casamino acids. This medium successfully enhanced the SAC-synthesizing activity of Lactococcus lactis ssp. cremoris NBRC 100676. In addition, microorganisms with high SAC-synthesizing activity were screened by the same medium. Food-related Klebsiella pneumoniae K-15 and Pantoea agglomerans P-3 were found to have a significantly increased SAC-synthesizing activity. The SAC-producing process established in this study is shorter in duration than the conventional garlic aging method. Furthermore, this study proposes a promising alternative strategy for producing food-grade SAC by microorganisms., (© The Author(s) 2022. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

In natural indigo dyeing, the water-insoluble indigo included in the composted indigo leaves called sukumo is converted to water-soluble leuco-indigo through the reduction activities of microorganisms under alkaline conditions. To understand the relationship between indigo reduction and microorganisms in indigo-fermentation suspensions, we isolated and identified the microorganisms that reduce indigo and analyzed the microbiota in indigo-fermentation suspensions. Indigo-reducing microorganisms, which were not isolated by means of a conventional indigo carmine-reduction assay method, were isolated by using indigo as a direct substrate and further identified and characterized. We succeeded in isolating bacteria closely related to Corynebacterium glutamicum, Chryseomicrobium aureum, and Enterococcus sp. for the first time. Anthraquinone was found to be an effective mediator that facilitated the indigo-reduction activity of the isolated strains. On analysis of the microbiota in indigo-fermentation suspensions, the ratio of indigo-reducing bacteria and others was found to be important for maintaining the indigo-reduction activity., (© The Author(s) 2021. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Maltol derivatives are used in a variety of fields due to their metal-chelating abilities. In the previous study, it was found that cytochrome P450 monooxygenase, P450nov, which has the ability to effectively convert the 2-methyl group in a maltol derivative, transformed 3-benzyloxy-2-methyl-4-pyrone (BMAL) to 2-(hydroxymethyl)-3-(phenylmethoxy)-4 H -pyran-4-one (BMAL-OH) and slightly to 3-benzyloxy-4-oxo-4  H -pyran-2-carboxaldehyde (BMAL-CHO). We isolated Pseudomonas nitroreducens SB32154 with the ability to convert BMAL-CHO to BMAL-COOH from soil. The enzyme responsible for aldehyde oxidation, a BMAL-CHO dehydrogenase, was purified from P. nitroreducens SB32154 and characterized. The purified BMAL-CHO dehydrogenase was found to be a xanthine oxidase family enzyme with unique structure of heterodimer composed of 75 and 15 kDa subunits containing a molybdenum cofactor and [Fe-S] clusters, respectively. The enzyme showed broad substrate specificity toward benzaldehyde derivatives. Furthermore, one-pot conversion of BMAL to BMAL-COOH via BMAL-CHO by the combination of the BMAL-CHO dehydrogenase with P450nov was achieved.

Cyclooxygenases are responsible for the production of prostaglandin H 2 (PGH 2 ) from arachidonic acid. PGH 2 can be converted into some bioactive prostaglandins, including prostaglandin F 2α (PGF 2α ), a potent chemical messenger used as a biological regulator in the fields of obstetrics and gynecology. The chemical messenger PGF 2α has been industrially produced by chemical synthesis. To develop a biotechnological process, in which PGF 2α can be produced by a microorganism, we transformed an oleaginous fungus, Mortierella alpina 1S-4, rich in triacylglycerol consisting of arachidonic acid using a cyclooxygenase gene from a red alga, Gracilaria vermiculophylla. PGF 2α was accumulated not only in the mycelia of the transformants but also in the extracellular medium. After 12 days of cultivation approximately 860 ng/g and 6421 µg/L of PGF 2α were accumulated in mycelia and the extracellular medium, respectively. The results could facilitate the development of novel fermentative methods for the production of prostanoids using an oleaginous fungus.

The establishment of renewable biofuel and chemical production is desirable because of global warming and the exhaustion of petroleum reserves. Sebacic acid (decanedioic acid), the material of 6,10-nylon, is produced from ricinoleic acid, a carbon-neutral material, but the process is not eco-friendly because of its energy requirements. Laccase-catalyzing oxidative cleavage of fatty acid was applied to the production of dicarboxylic acids using hydroxy and oxo fatty acids involved in the saturation metabolism of unsaturated fatty acids in Lactobacillus plantarum as substrates. Hydroxy or oxo fatty acids with a functional group near the carbon-carbon double bond were cleaved at the carbon-carbon double bond, hydroxy group, or carbonyl group by laccase and transformed into dicarboxylic acids. After 8 h, 0.58 mM of sebacic acid was produced from 1.6 mM of 10-oxo-cis-12,cis-15-octadecadienoic acid (αKetoA) with a conversion rate of 35% (mol/mol). This laccase-catalyzed enzymatic process is a promising method to produce dicarboxylic acids from biomass-derived fatty acids.