Summary
Lignin is the most abundant phenolic polymer; thus, its decomposition by microorganisms is fundamental to carbon cycling on earth. Lignin breakdown is initiated by depolymerization catalysed ...by extracellular oxidoreductases secreted by white‐rot basidiomycetous fungi. On the other hand, bacteria play a predominant role in the mineralization of lignin‐derived heterogeneous low‐molecular‐weight aromatic compounds. The outline of bacterial catabolic pathways for lignin‐derived bi‐ and monoaryls are typically composed of the following sequential steps: (i) funnelling of a wide variety of lignin‐derived aromatics into vanillate and syringate, (ii) O demethylation of vanillate and syringate to form catecholic derivatives and (iii) aromatic ring‐cleavage of the catecholic derivatives to produce tricarboxylic acid cycle intermediates. Knowledge regarding bacterial catabolic systems for lignin‐derived aromatic compounds is not only important for understanding the terrestrial carbon cycle but also valuable for promoting the shift to a low‐carbon economy via biological lignin valorisation. This review summarizes recent progress in bacterial catabolic systems for lignin‐derived aromatic compounds, including newly identified catabolic pathways and genes for decomposition of lignin‐derived biaryls, transcriptional regulation and substrate uptake systems. Recent omics approaches on catabolism of lignin‐derived aromatic compounds are also described.
The microbial conversion of lignin-derived aromatics is a promising strategy for the industrial utilization of this large biomass resource. However, efficient application requires an elucidation of ...the relevant transport and catabolic pathways. In
sp. strain SYK-6, most of the enzyme genes involved in 5,5'-dehydrodivanillate (DDVA) catabolism have been characterized, but the transporter has not yet been identified. Here, we identified SLG_07710 (
) and SLG_07780 (
), genes encoding a putative major facilitator superfamily (MFS) transporter and MarR-type transcriptional regulator, respectively. A
mutant of SYK-6 completely lost the capacity to grow on and convert DDVA. DdvR repressed the expression of the DDVA
-demethylase oxygenase component gene (
), while DDVA acted as the gene inducer. A DDVA uptake assay was developed by employing this DdvR-controlled
transcriptional regulatory system. A
UT26S transformant expressing
acquired DDVA uptake capacity, indicating that
encodes the DDVA transporter. DdvK, probably requiring the proton motive force, was suggested to be a novel MFS transporter on the basis of the amino acid sequence similarity. Subsequently, we evaluated the effects of
overexpression on the production of the DDVA metabolite 2-pyrone-4,6-dicarboxylate (PDC), a building block of functional polymers. A SYK-6 mutant of the PDC hydrolase gene (
) cultured in DDVA accumulated PDC via 5-carboxyvanillate and grew by utilizing 4-carboxy-2-hydroxypenta-2,4-dienoate. The introduction of a
-expression plasmid into a
mutant increased the growth rate in DDVA and the amounts of DDVA converted and PDC produced after 48 h by 1.35- and 1.34-fold, respectively. These results indicate that enhanced transporter gene expression can improve metabolite production from lignin derivatives.
The bioengineering of bacteria to selectively transport and metabolize natural substrates into specific metabolites is a valuable strategy for industrial-scale chemical production. The uptake of many substrates into cells requires specific transport systems, and so the identification and characterization of transporter genes are essential for industrial applications. A number of bacterial major facilitator superfamily transporters of aromatic acids have been identified and characterized, but many transporters of lignin-derived aromatic acids remain unidentified. The efficient conversion of lignin, an abundant but unutilized aromatic biomass resource, to value-added metabolites using microbial catabolism requires the characterization of transporters for lignin-derived aromatics. In this study, we identified the transporter gene responsible for the uptake of 5,5'-dehydrodivanillate, a lignin-derived biphenyl compound, in
sp. strain SYK-6. In addition to characterizing its function, we applied this transporter gene to the production of a value-added metabolite from 5,5'-dehydrodivanillate.
The Gram-positive bacterium Bacillus subtilis exhibits complex spatial and temporal gene expression signals. Although optogenetic tools are ideal for studying such processes, none has been engineered ...for this organism. Here, we port a cyanobacterial light sensor pathway comprising the green/red photoreversible two-component system CcaSR, two metabolic enzymes for production of the chromophore phycocyanobilin (PCB), and an output promoter to control transcription of a gene of interest into B. subtilis. Following an initial non-functional design, we optimize expression of pathway genes, enhance PCB production via a translational fusion of the biosynthetic enzymes, engineer a strong chimeric output promoter, and increase dynamic range with a miniaturized photosensor kinase. Our final design exhibits over 70-fold activation and rapid response dynamics, making it well-suited to studying a wide range of gene regulatory processes. In addition, the synthetic biology methods we develop to port this pathway should make B. subtilis easier to engineer in the future.
Objective Alongside non-pharmacological intervention, pharmacotherapy particularly with atypical antipsychotics is assumed to be effective for behavioral and psychological symptoms of dementia ...(BPSD).Methods This retrospective study investigated the effectiveness and safety of pharmacotherapy including antipsychotics in outpatients or inpatients with BPSD.Results Of all Alzheimer-type dementia (AD) patients with BPSD initiating treatment between March and August 2011, a total of 102 patients available for 12-month follow-up comprised the subjects in this chart review. Of these, 68 (66.7%) continued treatment in the ambulatory or inpatient setting, with their MMSE scores improved from 17.3 ± 3.6 at baseline to 18.3 ± 3.53, 17.9 ± 3.80 and 17.0 ± 4.14 after 3, 6 and 12 months, respectively. In contrast, their NPI scores were significantly different from 11.7 ± 11.2 at baseline to 4.86 ± 5.40, 3.56 ± 4.65 and 2.27 ± 3.77 after 3, 6 and 12 months, respectively. Of the 36 inpatients available for follow-up, 27 (75%) on concurrent antipsychotics (chlorpromazine CP equivalent, 162.2 mg) at baseline remained on concurrent antipsychotics (CP equivalent, 212.5 mg) after 12 months, while, of the 66 outpatients available for follow-up, 13 (19.7%) on concurrent antipsychotics (CP equivalent, 93.4 mg) at baseline remained on concurrent antipsychotics (CP equivalent, 113.0 mg) after 12 months.Conclusions Study results confirmed the effectiveness and safety of the study treatment in Japanese AD patients with BPSD for up to 12 months. How best to incorporate antipsychotics into the treatment of BPSD in clinical settings lies in the hands of us Japanese clinicians.
TonB-dependent transporters (TBDTs) mediate outer membrane transport of nutrients using the energy derived from proton motive force transmitted from the TonB-ExbB-ExbD complex localized in the inner ...membrane. Recently, we discovered ddvT encoding a TBDT responsible for the uptake of a 5,5-type lignin-derived dimer in Sphingobium sp. strain SYK-6. Furthermore, overexpression of ddvT in an SYK-6-derivative strain enhanced its uptake capacity, improving the rate of platform chemical production. Thus, understanding the uptake system of lignin-derived aromatics is fundamental for microbial conversion-based lignin valorization. Here we examined whether multiple tonB-, exbB-, and exbD-like genes in SYK-6 contribute to the outer membrane transport of lignin-derived aromatics. The disruption of tonB2-6 and exbB3 did not reduce the capacity of SYK-6 to convert or grow on lignin-derived aromatics. In contrast, the introduction of the tonB1-exbB1-exbD1-exbD2 operon genes into SYK-6, which could not be disrupted, promoted the conversion of β-O-4-, β-5-, β-1-, β-β-, and 5,5-type dimers and monomers, such as ferulate, vanillate, syringate, and protocatechuate. These results suggest that TonB-dependent uptake involving the tonB1 operon genes is responsible for the outer membrane transport of the above aromatics. Additionally, exbB2/tolQ and exbD3/tolR were suggested to constitute the Tol-Pal system that maintains the outer membrane integrity.
TonB-dependent receptors (TBDRs) mediate substrate-specific transport across the outer membrane, utilizing energy derived from the proton motive force transmitted from the TonB-ExbB-ExbD complex ...located in the inner membrane (TonB system). Although a number of TonB systems involved in the uptake of siderophores, vitamin B12 and saccharides have been identified, their involvement in the uptake and catabolism of aromatic compounds was previously unknown. Here, we show that the outer membrane transport of a biphenyl compound derived from lignin is mediated by the TonB system in a Gram-negative bacterium capable of degrading lignin-derived aromatic compounds,
sp. strain SYK-6. Furthermore, we found that overexpression of the corresponding TBDR gene enhanced the uptake of this biphenyl compound, contributing to the improved rate of platform chemical production. Our results will provide an important basis for establishing engineered strains optimized for use in lignin valorisation.
Iron, an essential element for all organisms, acts as a cofactor of enzymes in bacterial degradation of recalcitrant aromatic compounds. The bacterial family, Sphingomonadaceae comprises various ...degraders of recalcitrant aromatic compounds; however, little is known about their iron acquisition system. Here, we investigated the iron acquisition system in a model bacterium capable of degrading lignin-derived aromatics, Sphingobium sp. strain SYK-6. Analyses of SYK-6 mutants revealed that FiuA (SLG_34550), a TonB-dependent receptor (TBDR), was the major outer membrane iron transporter. Three other TBDRs encoded by SLG_04340, SLG_04380, and SLG_10860 also participated in iron uptake, and tonB2 (SLG_34540), one of the six tonB comprising the Ton complex which enables TBDR-mediated transport was critical for iron uptake. The ferrous iron transporter FeoB (SLG_36840) played an important role in iron uptake across the inner membrane. The promoter activities of most of the iron uptake genes were induced under iron-limited conditions, and their regulation is controlled by SLG_29410 encoding the ferric uptake regulator, Fur. Although feoB, among all the iron uptake genes identified is highly conserved in Sphingomonad strains, the outer membrane transporters seem to be diversified. Elucidation of the iron acquisition system promises better understanding of the bacterial degradation mechanisms of aromatic compounds.
The number of wheat grains is one of the major determinants of yield. Many quantitative trait loci (QTLs) and some causal genes such as
GNI-A1
and
WAPO-A1
that are associated with grain number per ...spike (GNS) have been identified, but the underlying mechanisms remain largely unknown. We analyzed QTLs for grain number and other related traits using 188 doubled haploid lines derived from the Japanese high-yield variety, Kitahonami, as a parent to elucidate the genetic mechanism determining grain number. The major QTLs for grain number at the apical, central, and basal parts of the spike were identified in different chromosomal regions. We considered
GNI-A1
and
WAPO-A1
as candidate genes controlling grain number at the central and basal parts of the spike, respectively. Kitahonami had the favorable 105Y allele of
GNI-A1
and
WAPO-A1b
allele and unfavorable alleles of QTLs for grain number at the apical part of spikes. Pyramiding the favorable alleles of these QTLs significantly increased GNS without significantly reducing thousand-grain weight (TGW). In contrast, the accumulation of favorable alleles of QTLs for TGW significantly decreased GNS, whereas days to heading positively correlated with GNS. Late heading increased the spikelet number per spike, resulting in a higher GNS. Pyramiding of the QTLs for TGW and days to heading also altered the GNS. In conclusion, GNS is a complex trait controlled by many QTLs, and it is essential for breeding to design.
Effect of retained austenite characteristics on V-bending in ultrahigh-strength TRIP-aided steel sheets with bainitic ferrite matrix (TBF steel) was investigated for automotive applications. ...V-bending tests were performed on a servohydraulic testing machine at a processing speed of 1 mm/min using a 88-degree V-punch (2.0 mm in punch radius), 88-degree V-die (12 mm in die gap, 0.8 mm in die shoulder radius), and a rectangular specimen (50 mm in length, 5 mm in width, 1.2 mm in thickness). The results are summarized as follows.(1) The 0.2C-1.5Si-1.5Mn (mass%) TBF steel sheets were able to perform V-bending by strain-induced martensitic transformation of TRIP effect. On the other hand, ferrite-martensite dual-phase (MDP0) steel sheet of 900 MPa grade was not able to perform 90-degree V-bending because of initiation of crack in tension area.(2) The TBF375 steel sheet that produced by heat treatment of annealing at 1173 K (900°C) for 1200 s followed by austempering at 648 K (375°C) for 200 s, of 1100 MPa grade was able to enable the 90-degree V-bending that considered an amount of springback (Δθ=θ1−θ2), in which the θ1 and the θ2 were a bending angle on loading and a bending angle after unloading respectively, of more than 2-degree by controlling a displacement of punch bottom dead center.
At the major vernalization locus ‘Vrn-D1’, the spring allele, Vrn-D1a, and two winter alleles, Vrn-D1b and vrn-D1, have been identified in wheat. We conducted field trials to determine the effects of ...alleles on growth and yield-related traits, using near-isogenic lines developed in the genetic background of spring type wheat cultivars, ‘Abukumawase’ and ‘Asakazekomugi’, both of which carry the Vrn-D1a allele. Although maturity date of three alleles was same, the panicle development occurred earlier in the following order of genotype: Vrn-D1a > Vrn-D1b > vrn-D1. There was a significant difference in panicle development even between two winter type alleles vrn-D1 and Vrn-D1b. Grain yield and the spikelet number per spike of the original spring type cultivars were lower than those of the winter type NILs. In addition, while the young panicle development of the tillers in the spring type cultivars was found to be two weeks to one month later in the tillers than that in the main stem, young panicle development of the main stem and tillers in the winter type NILs were almost identical. Hence, winter type wheat bearing vrn-D1 which exhibit later panicle development than that bearing Vrn-D1b, was elucidated to might be more useful especially in areas with high risk of frost damage. Spring type wheat had a lower sink capacity and grain yield, meanwhile that was considered to prevent severe frost damage by allowing late-developed tillers to survive.
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