IMPORTANCE Strobilurin fungicides have been widely acknowledged as an essential group of pesticides worldwide. So far, their residues and toxic effects on aquatic organisms have been reported in different parts of the world. Microbial degradation can eliminate xenobiotics from the environment. Therefore, the degradation of strobilurin fungicides by microorganisms has also been reported. However, little is known about the involvement of enzymes or genes in strobilurin fungicide degradation. In this study, a novel esterase gene responsible for the detoxification of strobilurin fungicides, strH, was cloned in the newly isolated strain Hyphomicrobium sp. DY-1. This degradation process detoxifies the strobilurin fungicides and relieves their growth inhibition of Chlorella.Lactate-driven chain elongation (LCE) has emerged as a new biotechnology to upgrade organic waste streams into a valuable biochemical and fuel precursor, medium-chain carboxylate, n-caproate. Considering that a low cost of downstream extraction is critical for biorefinery technology, a high concentration of n-caproate production is very important to improve the scale-up of the LCE process. We report here that in a nonsterile open environment, the n-caproate concentration was increased from the previous record of 25.7 g·liter-1 to a new high level of 33.7 g·liter-1 (76.8 g chemical oxygen demand [COD]·liter - 1), with the highest production rate being 11.5 g·liter-1·day-1 (26.2 g COD·liter - 1·day-1). In addition, the LCE process remained stable, with an average concentration of n-caproate production of 20.2 ± 5.62 g·liter-1 (46.1 ± 12.8 g COD·liter - 1) for 780 days. Dynamic changes in taxonomic composition integrated with metagenomic data reveal the microbial ecology for long-term production of high concentrE process. We anticipate that our research will rapidly advance LCE biotechnology with the goal of promoting the sustainable development of human society.Cyclodipeptide synthases (CDPSs) catalyze the formation of cyclodipeptides using aminoacylated tRNAs as the substrates and have great potential in the production of diverse 2,5-diketopiperazines (2,5-DKPs). Genome mining of Streptomyces leeuwenhoekii NRRL B-24963 revealed a two-gene locus, saz, encoding CDPS SazA and a unique fused enzyme (SazB) harboring two domains phytoene synthase-like prenyltransferase (PT) and methyltransferase (MT). Heterologous expression of the saz gene(s) in Streptomyces albus J1074 led to the production of four prenylated indole alkaloids, among which streptoazines A to C (compounds 3 to 5) are new compounds. Expression of different gene combinations showed that the SazA catalyzes the formation of cyclo(l-Trp-l-Trp) (cWW; compound 1), followed by consecutive prenylation and methylation by SazB. Biochemical assays demonstrated that SazB is a bifunctional enzyme, catalyzing sequential C-3/C-3' prenylation(s) by SazB-PT and N-1/N-1' methylation(s) by SazB-MT. Of note, the substrate selectivity of SazB-PT and SazB-MT was probed, revealing the stringent specificity of SazB-PT but relative flexibility of SazB-MT.IMPORTANCE Natural products with a 2,5-diketopiperazine (2,5-DKP) skeleton have long sparked interest in drug discovery and development. Recent advances in microbial genome sequencing have revealed that the potential of cyclodipeptide synthase (CDPS)-dependent pathways encoding new 2,5-DKPs are underexplored. In this study, we report the genome mining of a new CDPS-encoding two-gene operon and activation of this cryptic gene cluster through heterologous expression, leading to the discovery of four indole 2,5-DKP alkaloids. The cyclo(l-Trp-l-Trp) (cWW)-synthesizing CDPS SazA and the unusual prenyltransferase (PT)-methyltransferase (MT) fused enzyme SazB were characterized. Our results expand the repertoire of CDPSs and associated tailoring enzymes, setting the stage for accessing diverse prenylated alkaloids using synthetic biology strategies.Coastal wetlands are experiencing frequent flooding because of global climate changes, such as the rising sea level. Despite the key role of archaea in soil biogeochemical cycles, the assembly processes and co-occurrence patterns of archaeal communities in coastal wetlands in response to increasing inundation frequencies remain elusive. In this study, we established an in situ mesocosm with an inundation frequency gradient to investigate the response of soil archaeal community toward increasing inundation frequencies in monocultures of Spartina alterniflora and a mangrove species, Kandelia obovata Both neutral community model and null model analyses suggested that stochastic processes are dominant in governing the archaeal community assembly and that the stochastic processes are enhanced with increasing inundation frequencies. Increasing inundation frequencies significantly increased the community niche width. Moreover, archaeal community in S. alterniflora soil displayed lower niche overlap and higher stochaing inundation frequencies enhance the stochastic processes and network complexity of the soil archaeal community. This study offers a new path for an improved understanding of archaeal community assembly and species coexistence in coastal environments, with a special focus on the role of inundation frequency.Gene expression in the obligately aerobic acetic acid bacterium Gluconobacter oxydans responds to oxygen limitation, but the regulators involved are unknown. In this study, we analyzed a transcriptional regulator named GoxR (GOX0974), which is the only member of the fumarate-nitrate reduction regulator (FNR) family in this species. Evidence that GoxR contains an iron-sulfur cluster was obtained, suggesting that GoxR functions as an oxygen sensor similar to FNR. https://www.selleckchem.com/products/pf-562271.html The direct target genes of GoxR were determined by combining several approaches, including a transcriptome comparison of a ΔgoxR mutant with the wild-type strain and detection of in vivo GoxR binding sites by chromatin affinity purification and sequencing (ChAP-Seq). Prominent targets were the cioAB genes encoding a cytochrome bd oxidase with low O2 affinity, which were repressed by GoxR, and the pnt operon, which was activated by GoxR. The pnt operon encodes a transhydrogenase (pntA1A2B), an NADH-dependent oxidoreductase (GOX0313), and another oxidoreductase (GOX0314).
IMPORTANCE Strobilurin fungicides have been widely acknowledged as an essential group of pesticides worldwide. So far, their residues and toxic effects on aquatic organisms have been reported in different parts of the world. Microbial degradation can eliminate xenobiotics from the environment. Therefore, the degradation of strobilurin fungicides by microorganisms has also been reported. However, little is known about the involvement of enzymes or genes in strobilurin fungicide degradation. In this study, a novel esterase gene responsible for the detoxification of strobilurin fungicides, strH, was cloned in the newly isolated strain Hyphomicrobium sp. DY-1. This degradation process detoxifies the strobilurin fungicides and relieves their growth inhibition of Chlorella.Lactate-driven chain elongation (LCE) has emerged as a new biotechnology to upgrade organic waste streams into a valuable biochemical and fuel precursor, medium-chain carboxylate, n-caproate. Considering that a low cost of downstream extraction is critical for biorefinery technology, a high concentration of n-caproate production is very important to improve the scale-up of the LCE process. We report here that in a nonsterile open environment, the n-caproate concentration was increased from the previous record of 25.7 g·liter-1 to a new high level of 33.7 g·liter-1 (76.8 g chemical oxygen demand [COD]·liter - 1), with the highest production rate being 11.5 g·liter-1·day-1 (26.2 g COD·liter - 1·day-1). In addition, the LCE process remained stable, with an average concentration of n-caproate production of 20.2 ± 5.62 g·liter-1 (46.1 ± 12.8 g COD·liter - 1) for 780 days. Dynamic changes in taxonomic composition integrated with metagenomic data reveal the microbial ecology for long-term production of high concentrE process. We anticipate that our research will rapidly advance LCE biotechnology with the goal of promoting the sustainable development of human society.Cyclodipeptide synthases (CDPSs) catalyze the formation of cyclodipeptides using aminoacylated tRNAs as the substrates and have great potential in the production of diverse 2,5-diketopiperazines (2,5-DKPs). Genome mining of Streptomyces leeuwenhoekii NRRL B-24963 revealed a two-gene locus, saz, encoding CDPS SazA and a unique fused enzyme (SazB) harboring two domains phytoene synthase-like prenyltransferase (PT) and methyltransferase (MT). Heterologous expression of the saz gene(s) in Streptomyces albus J1074 led to the production of four prenylated indole alkaloids, among which streptoazines A to C (compounds 3 to 5) are new compounds. Expression of different gene combinations showed that the SazA catalyzes the formation of cyclo(l-Trp-l-Trp) (cWW; compound 1), followed by consecutive prenylation and methylation by SazB. Biochemical assays demonstrated that SazB is a bifunctional enzyme, catalyzing sequential C-3/C-3' prenylation(s) by SazB-PT and N-1/N-1' methylation(s) by SazB-MT. Of note, the substrate selectivity of SazB-PT and SazB-MT was probed, revealing the stringent specificity of SazB-PT but relative flexibility of SazB-MT.IMPORTANCE Natural products with a 2,5-diketopiperazine (2,5-DKP) skeleton have long sparked interest in drug discovery and development. Recent advances in microbial genome sequencing have revealed that the potential of cyclodipeptide synthase (CDPS)-dependent pathways encoding new 2,5-DKPs are underexplored. In this study, we report the genome mining of a new CDPS-encoding two-gene operon and activation of this cryptic gene cluster through heterologous expression, leading to the discovery of four indole 2,5-DKP alkaloids. The cyclo(l-Trp-l-Trp) (cWW)-synthesizing CDPS SazA and the unusual prenyltransferase (PT)-methyltransferase (MT) fused enzyme SazB were characterized. Our results expand the repertoire of CDPSs and associated tailoring enzymes, setting the stage for accessing diverse prenylated alkaloids using synthetic biology strategies.Coastal wetlands are experiencing frequent flooding because of global climate changes, such as the rising sea level. Despite the key role of archaea in soil biogeochemical cycles, the assembly processes and co-occurrence patterns of archaeal communities in coastal wetlands in response to increasing inundation frequencies remain elusive. In this study, we established an in situ mesocosm with an inundation frequency gradient to investigate the response of soil archaeal community toward increasing inundation frequencies in monocultures of Spartina alterniflora and a mangrove species, Kandelia obovata Both neutral community model and null model analyses suggested that stochastic processes are dominant in governing the archaeal community assembly and that the stochastic processes are enhanced with increasing inundation frequencies. Increasing inundation frequencies significantly increased the community niche width. Moreover, archaeal community in S. alterniflora soil displayed lower niche overlap and higher stochaing inundation frequencies enhance the stochastic processes and network complexity of the soil archaeal community. This study offers a new path for an improved understanding of archaeal community assembly and species coexistence in coastal environments, with a special focus on the role of inundation frequency.Gene expression in the obligately aerobic acetic acid bacterium Gluconobacter oxydans responds to oxygen limitation, but the regulators involved are unknown. In this study, we analyzed a transcriptional regulator named GoxR (GOX0974), which is the only member of the fumarate-nitrate reduction regulator (FNR) family in this species. Evidence that GoxR contains an iron-sulfur cluster was obtained, suggesting that GoxR functions as an oxygen sensor similar to FNR. https://www.selleckchem.com/products/pf-562271.html The direct target genes of GoxR were determined by combining several approaches, including a transcriptome comparison of a ΔgoxR mutant with the wild-type strain and detection of in vivo GoxR binding sites by chromatin affinity purification and sequencing (ChAP-Seq). Prominent targets were the cioAB genes encoding a cytochrome bd oxidase with low O2 affinity, which were repressed by GoxR, and the pnt operon, which was activated by GoxR. The pnt operon encodes a transhydrogenase (pntA1A2B), an NADH-dependent oxidoreductase (GOX0313), and another oxidoreductase (GOX0314).
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