Bioscience, Biotechnology, and Biochemistry最新文献

Euglena gracilis cells grown in the dark accumulate a β-1,3-glucan called paramylon, synthesized from organic carbon sources. Paramylon has potential applications as a raw material for bioplastics and nanofibers. Strain SM-ZK, a streptomycin-bleached mutant of E. gracilis, lacks chloroplasts permanently and accumulates more paramylon than the wild-type strain. However, data are limited on the fermentation characteristics of this mutant strain. This study compares the cultivation characteristics of E. gracilis strains Z (wild-type strain) and SM-ZK under fed-batch cultivation conditions. Strain SM-ZK showed significantly higher productivity in terms of both biomass yield and glucose consumption than strain Z. Moreover, strain SM-ZK cells appeared to be gradually enlarged during fed-batch cultivation compared with strain Z that grows in uniform sizes. These novel findings support the potential use of strain SM-ZK for industrial-scale production of paramylon.

Reactive carbonyl species (RCS), such as acrolein (Acr), are generated through the degradation of lipid peroxides and exert cytotoxic effects. To identify natural RCS scavengers, we examined 80% ethanol extracts from 46 angiosperm species for Acr-trapping activity using an HPLC-based assay. Strong activities were observed in several taxa, including garlic, spinach, avocado, broccoli, and lotus. In garlic, the active metabolite was identified as S-allyl-L-cysteine sulfoxide (alliin), a characteristic Allium amino acid. Alliin and its S-(1E)-propenyl and S-methyl derivatives (isoalliin and methiin, respectively) trapped up to two Acr molecules at the amino group and exhibited higher activities than known scavengers such as carnosine and epigallocatechin gallate. These findings highlight S-alk(en)yl-L-cysteine sulfoxides as potent secondary antioxidants and suggest that structurally diverse RCS scavengers remain to be discovered in plants.

The brown alga Dictyopteris polypodioides produces a variety of sesquiterpene derivatives. However, its potential as an antimelanogenic agent remains unclear. In this study, we investigated the ability of D. polypodioides extract and its constituent compounds to inhibit melanin biosynthesis. Methanolic extracts of D. polypodioides significantly suppressed melanin accumulation in B16 melanoma 4A5 cells. We identified four sesquiterpene hydroquinone derivatives, zonarol (1), yahazunol (2), isozonarol (3), and chromazonarol (6), as active constituents. Structure-activity relationship analyses, including those of semisynthetic analogs, indicated that the hydroquinone moiety is crucial for the antimelanogenesis activity. Chromazonarol (6), which lacks a hydroquinone group, inhibits tyrosinase (monophenolase) in an uncompetitive manner, with 50% inhibitory concentration of 6.2 µm. Quantitative analysis revealed that these sesquiterpene derivatives accounted for approximately 5.6% of the dried algal biomass. D. polypodioides is a promising natural source of bioactive compounds with potential applications in preventing melanogenesis and food browning.

Bionanocapsules (BNCs), hollow nanoparticles derived from the hepatitis B virus (HBV) surface L protein, originated from HB vaccine development and have evolved into a versatile biotechnological platform. Evolving from the first-generation S antigen vaccine, we developed second-generation (M antigen) and third-generation (L antigen) vaccines with enhanced protective efficacy, the latter giving rise to BNCs. BNCs retain the human liver-specific infection machinery of HBV and exhibit stealth, targeting, and endosomal escape abilities as a drug delivery system (DDS). Furthermore, BNCs have been applied to re-targeting via antibody display and as nanoscaffolds for high-sensitivity biosensors, resulting in breakthroughs across DDS, infection-mechanism elucidation, and biosensing technologies.

Rice produces a diverse array of phytoalexins, including diterpenoid compounds (momilactones and phytocassanes) and the flavonoid sakuranetin, which serve as crucial defense metabolites against environmental stresses such as pathogen attack. This review summarizes the regulatory mechanisms and evolutionary insights of rice phytoalexin biosynthesis. Jasmonoyl-l-isoleucine (JA-Ile) is one of the signal molecules inducing phytoalexin production. OsCOI2 functions as the primary JA-Ile receptor for phytoalexin production. Multiple transcription factors, including DPF (Diterpenoid phytoalexin factor)/bHLH25 (basic helix-loop-helix 25), OsTGAP1 (Oryza sativa TGA factor for phytoalexin production 1), and various WRKY transcription factors, coordinately regulate the expression of biosynthetic genes. Remarkably, genes encoding diterpenoid phytoalexin biosynthetic enzymes are organized into biosynthetic gene clusters in the rice genome. Comparative genomic analyses reveal dynamic evolutionary processes involving gene duplications, cluster rearrangements, and occasional losses across Oryza species. These findings provide fundamental insights into the evolution of plant chemical defense and offer potential strategies for developing stress-tolerant crops by targeting the manipulation of phytoalexin biosynthetic pathways and their regulatory networks.

Poly-γ-glutamic acid (γ-PGA) occurs in three stereochemical forms-L-, DL-, and D-polymers-and the D/L ratio profoundly affects crystallinity, degradability, and materials performance. Bacillus subtilis and related secretors typically produce DL-PGA, whereas halophilic archaea yield stereoregular L-PGA and Bacillus anthracis forms a covalently anchored D-PGA capsule. Recent work has clarified how the PgsBCA/CapBCA modules access these outputs: PgsB and PgsC build and export a purely L-Glu polymer, while the MslH-like enzyme PgsA/CapA introduces D-Glu, establishing the D/L ratio. In the extracellular space, the D/L composition of γ-PGA is shaped by stereoselective hydrolases-PgdS, NlpC/P60 DL-endopeptidases, phage-derived Pgh enzymes, and GGT-family proteins. We integrate these biosynthetic and degradative pathways into a stereochemical framework and outline how tuning epimerase activity and controlling these hydrolases may enable high-molecular-weight, L-rich γ-PGA in Bacillus for coatings, absorbents, biomedical applications, and personal-care formulations where L-PGA surpasses DL-PGA in moisture retention and stability.

Molybdenum and tungsten are essential trace metals whose biological utilization requires strict and selective control of their uptake and intracellular availability. Prokaryotes achieve this through highly specialized systems, involving the oxyanion-specific ATP-binding cassette transporters (ModABC, WtpABC, and TupABC), which discriminate between molybdate and tungstate via distinct periplasmic binding mechanisms. Following molybdenum import, the molybdenum storage proteins store up to ∼130 molybdate ions as polyoxometalate clusters within a protein cage via an ATP-dependent sequestration mechanism. These transport and storage strategies maintain metal homeostasis even under nutrient-limiting conditions, allowing sustained biosynthesis of molybdoenzymes and illustrating an advanced paradigm for microbial trace metal regulation.

Mycosporine-like amino acids (MAAs) are natural compounds widely studied for their photoprotective and antioxidant properties. Typical MAAs consist of one or two amino acids attached to a cyclohexenone or cyclohexenimine ring, whereas atypical MAAs possess unique chemical modifications such as glycosylation and methylation. Recently, we identified an atypical MAA, GlcHMS326, from the cyanobacterium Gloeocapsa sp. BRSZ, characterized by glycosylation, methylation, and hydroxylation. In this study, we compared the chemical stability and biological activities of GlcHMS326 with those of a typical di-substituted MAA, porphyra-334. GlcHMS326 was less stable under high-temperature conditions but showed a slightly higher residual rate than porphyra-334 under the present visible-light exposure conditions. Functionally, GlcHMS326 showed stronger antioxidant and collagenase inhibitory activities but weaker antiglycative activity. Neither compound inhibited hyaluronidase activity. Both MAAs inhibited angiotensin-converting enzyme, with porphyra-334 showing stronger inhibition. These results provide insights into how chemical modifications influence the functional properties of MAAs.

Jasmonate is a plant hormone that regulates development and defense responses. Jasmonoyl-L-isoleucine (JA-Ile) is a ligand for the most studied jasmonate co-receptor, COI1-JAZ, in seed plants. 12-Oxygenation to 12-hydroxyjasmonoyl-L-isoleucine (12-OH-JA-Ile) is a major metabolic pathway of JA-Ile. Moreover, 12-OH-JA-Ile is a selective ligand for some COI1-JAZ pairs in Arabidopsis thaliana. However, few studies have reported on the activity of 12-OH-JA-Ile in rice (Oryza sativa L.). In this study, we synthesized 12-OH-JA-Ile and its isomers, and evaluated their biological activities against rice. 12-OH-JA-Ile inhibited root elongation but did not induce the biosynthesis of momilactone A, a phytoalexin. These results suggested that 12-OH-JA-Ile selectively induced a jasmonate response in rice. The bioactivity of the E-isomer of 12-OH-JA-Ile revealed that the Z-olefin was necessary for root inhibitory activity.

We identify a novel effect in which dietary purple non-sulfur bacteria Cereibacter sphaeroides increase body size in Caenorhabditis elegans. This response requires the Toll-like receptor homolog TOL-1 and the TIR-domain adaptor TIR-1, but not the p38 MAP kinase PMK-1. Components of the DBL-1/BMP pathway, including LON-1, also contribute, revealing a new interaction between a beneficial bacterium and host growth regulation.