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We focused on the production of docosahexaenoic acid (DHA)-containing microbial lipids by Aurantiochytrium sp. using of defatted soybean (DS) as a nitrogen source. Defatted soybean is a plant biomass that could provide a sustainable supply at a low cost. Results showed that Aurantiochytrium sp. could not directly assimilate the DS as a nitrogen source but could grow well in a medium containing DS fermented with rice malt. When cultivated in a fermented DS (FDS) medium, Aurantiochytrium sp. showed vigorous growth with the addition of sufficient sulfate and chloride ions as inorganic nutrients without seawater salt. A novel isolated Aurantiochytrium sp. 6-2 showed 15.8 ± 3.4 g/L DHA productivity (in 54.8 ± 12.1 g/L total fatty acid production) in 1 L of the FDS medium. Therefore, DHA produced by Aurantiochytrium sp. using FDS enables a stable and sustainable DHA supply and could be an alternative source of natural DHA derived from fish oil. [ABSTRACT FROM AUTHOR]

ω3 Polyunsaturated fatty acids are currently obtained mainly from fisheries; thus, sustainable alternative sources such as oleaginous microorganisms are required. Here, we describe the isolation, characterization, and application of 3 novel ω3 desaturases with ω3 polyunsaturated fatty acid–producing activity at ordinary temperatures (28 °C). First, we selected Pythium sulcatum and Plectospira myriandra after screening for oomycetes with high eicosapentaenoic acid/arachidonic acid ratios and isolated the genes psulω3 and pmd17 , respectively, which encode ω3 desaturases. Subsequent characterization showed that PSULω3 exhibited ω3 desaturase activity on both C18 and C20 ω6 polyunsaturated fatty acids while PMD17 exhibited ω3 desaturase activity exclusively on C20 ω6 polyunsaturated fatty acids. Expression of psulω3 and pmd17 in the arachidonic acid–producer Mortierella alpina resulted in transformants that produced eicosapentaenoic acid/total fatty acid values of 38% and 40%, respectively, at ordinary temperatures. These ω3 desaturases should facilitate the construction of sustainable ω3 polyunsaturated fatty acid sources. [ABSTRACT FROM AUTHOR]

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)-4H-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. Enzymatic conversion of BMAL to BMAL-COOH by P450nov from Novosphingobium sp. SB32149 and BMAL-CHO dehydrogenase from Pseudomonas nitroreducens SB32154 [ABSTRACT FROM AUTHOR]

Cyclooxygenases are responsible for the production of prostaglandin H2 (PGH2) from arachidonic acid. PGH2 can be converted into some bioactive prostaglandins, including prostaglandin F2α (PGF2α), a potent chemical messenger used as a biological regulator in the fields of obstetrics and gynecology. The chemical messenger PGF2α has been industrially produced by chemical synthesis. To develop a biotechnological process, in which PGF2α 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. PGF2α 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 PGF2α 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. [ABSTRACT FROM AUTHOR]

Nitrifying microbial consortia were enriched from bark compost in a water system by regulating the amounts of organic nitrogen compounds and by controlling the aeration conditions with addition of CaCO3for maintaining suitable pH. Repeated enrichment showed reproducible mineralization of organic nitrogen via the conversion of ammonium ions () and nitrite ions () into nitrate ions (). The change in microbial composition during the enrichment was investigated by PCR-DGGE analysis with a focus on prokaryote, ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and eukaryote cell types. The microbial transition had a simple profile and showed clear relation to nitrogen ions transition.NitrosomonasandNitrobacterwere mainly detected duringandoxidation, respectively. These results revealing representative microorganisms acting in each ammonification and nitrification stages will be valuable for the development of artificial simple microbial consortia for organic hydroponics that consisted of identified heterotrophs and autotrophic nitrifying bacteria. Investigation of the transition of a nitrifying microbial community in relation to the transition of nitrogen in the organic hydroponic system. [ABSTRACT FROM PUBLISHER]

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 inLactobacillus plantarumas 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. Oxidative cleavage of oxo unsaturated fatty acid into dicarboxylic acid by laccase. [ABSTRACT FROM PUBLISHER]

2′-O-Methylribonucleosides (2′-OMe-NRs) are promising raw materials for nucleic acid drugs because of their high thermal stability and nuclease tolerance. In the course of microbial screening for metabolic activity toward 2′-OMe-NRs,Lactobacillus buchneriLBK78 was found to decompose 2′-O-methyluridine (2′-OMe-UR). The enzyme responsible was partially purified fromL. buchneriLBK78 cells by a four-step purification procedure, and identified as a novel nucleoside hydrolase. This enzyme,LbNH, belongs to the nucleoside hydrolase superfamily, and formed a homotetrameric structure composed of subunits with a molecular mass around 34 kDa.LbNH hydrolyzed 2′-OMe-UR to 2′-O-methylribose and uracil, and the kinetic constants wereKmof 0.040 mM,kcatof 0.49 s−1, andkcat/Kmof 12 mM−1 s−1. In a substrate specificity analysis,LbNH preferred ribonucleosides and 2′-OMe-NRs as its hydrolytic substrates, but reacted weakly with 2′-deoxyribonucleosides. In a phylogenetic analysis,LbNH showed a close relationship with purine-specific nucleoside hydrolases from trypanosomes. LbNH, a novel nucleoside hydrolase fromLactobacillus buchneriLBK 78 catalyzes 1'-hydrolysis reaction toward 2'-O-methyluridine to form 2'-O-methylribose and uracil as the degradation products. [ABSTRACT FROM PUBLISHER]