Heterotrophic nitrification by Alcaligenes faecalis links organic and inorganic nitrogen metabolism.

Heterotrophic nitrification remains a mystery for decades. It has been commonly hypothesized that heterotrophic nitrifiers oxidize ammonia to hydroxylamine and then to nitrite in a way similar to autotrophic AOA and AOB. Recently, heterotrophic nitrifiers from Alcaligenes were found to oxidize ammonia to hydroxylamine and then to N2 ("dirammox", direct ammonia oxidation) by the gene cluster dnfABC with a yet-to-be-reported mechanism.

Cofactor-independent C-C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis.

Biosynthesis of atypical angucyclines involves unique oxidative B-ring cleavage and rearrangement reactions, which are catalyzed by AlpJ-family oxygenases, including AlpJ, JadG, and GilOII. Prior investigations established the essential requirement for FADH/FMNH as cofactors when utilizing the quinone intermediate dehydrorabelomycin as a substrate. In this study, we unveil a previously unrecognized facet of these enzymes as cofactor-independent oxygenases when employing the hydroquinone intermediate CR1 as a substrate.

Environmental Adaptability and Organic Pollutant Degradation Capacity of a Novel Species Derived from Soil in the Uninhabited Area of the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau (QTP) is known for extreme natural environments and, surprisingly, has been reported to contain widespread organic pollutants. can survive a variety of extreme environments and degrade many organic contaminants. Here, we isolated a strain (FXJ9.

Isolation and Identification of Efficient Malathion-Degrading Bacteria from Deep-Sea Hydrothermal Sediment.

The genetic and metabolic diversity of deep-sea microorganisms play important roles in phosphorus and sulfur cycles in the ocean, distinguishing them from terrestrial counterparts. Malathion is a representative organophosphorus component in herbicides, pesticides, and insecticides and is analogues of neurotoxic agent. Malathion has been one of the best-selling generic organophosphate insecticides from 1980 to 2012.

Macrocycle molecule-based cryoprotectants for ice recrystallization inhibition and cell cryopreservation.

Cyclodextrin-based cryoprotectants were developed. α-TMCD, which can be easily put into large-scale production, showed enhanced cell viabilities of 19.97 ± 0.

Identification and characterization of a novel hydroxylamine oxidase, DnfA, that catalyzes the oxidation of hydroxylamine to N.

Nitrogen (N) gas in the atmosphere is partially replenished by microbial denitrification of ammonia. Recent study has shown that Alcaligenes ammonioxydans oxidizes ammonia to dinitrogen via a process featuring the intermediate hydroxylamine, termed "Dirammox" (direct ammonia oxidation). However, the unique biochemistry of this process remains unknown.

Dirammox Is Widely Distributed and Dependently Evolved in and Is Important to Nitrogen Cycle.

Nitrogen cycle is an essential process for environmental health. Dirammox (ect onia idation), encoded by the cluster, was a novel pathway for microbial N production defined in HO-1. Here, a copy of the cluster as a whole was proved to have existed and very conserved in all genomes.

Identification of the Biosynthetic Pathway of Glycine Betaine That Is Responsible for Salinity Tolerance in Halophilic D301.

D301 has been widely used in the biodesulfurization process, as it is capable of oxidizing hydrogen sulfide to elemental sulfur under strongly halo-alkaline conditions. Glycine betaine contributes to the increased tolerance to extreme environments in some of species. However, the biosynthetic pathway of glycine betaine in remained unknown.

Transcriptome-guided identification of a four-component system, SbrH1-R, that modulates milbemycin biosynthesis by influencing gene cluster expression, precursor supply, and antibiotic efflux.

can produce numerous antibiotics and many other bioactive compounds. Recently, the molecular mechanisms of transcriptional regulators in control of antibiotic production by influencing the expression of biosynthetic gene clusters (BGCs) have been extensively studied. However, for regulators that affect both antibiotic production and cell growth, the way to influence antibiotic production may be diverse, but related studies are limited.

TerC Is a Multifunctional and Promiscuous Flavoprotein Monooxygenase That Catalyzes Bimodal Oxidative Transformations.

The flavoprotein monooxygenase (FPMO) TerC is encoded by all known cyclopentene biosynthetic gene clusters. It can catalyze oxidative dearomatization toward a series of 6-HM analogues and further induces different skeletal distortions to form either benzoquinone or pyrone by bimodal reaction cascades, which is only governed by the C7 substitutions. Beyond our study demonstrated bimodal reaction cascades and advanced the biosynthetic knowledge of fungal cyclopentenes, this work also sets the stage for the bioengineering of 6-HM polyketides.

Novel Alcaligenes ammonioxydans sp. nov. from wastewater treatment sludge oxidizes ammonia to N with a previously unknown pathway.

Heterotrophic nitrifiers are able to oxidize and remove ammonia from nitrogen-rich wastewaters but the genetic elements of heterotrophic ammonia oxidation are poorly understood. Here, we isolated and identified a novel heterotrophic nitrifier, Alcaligenes ammonioxydans sp. nov.

Detection, Structural Elucidation, and Biological Effects of Diverse -Acyl-homoserine Lactone Signaling Molecules in the Plant-Promoting Endophytic Bacterium M15.

Quorum sensing (QS), usually performed by -acyl-homoserine lactones (AHLs) in Gram-staining-negative bacteria, plays an important role in plant-bacteria interactions. M15 is a plant-growth-promoting rhizobacterium (PGPR) isolated from rice roots. In this study, we found a QS system in the endogenous plasmid of M15 and detected the activity of AHLs by a bioassay method.

Positional Isomeric Effects on the Optical Properties, Multivalent Glycosidase Inhibition Effect, and Hypoglycemic Effect of Perylene Bisimide-deoxynojirimycin Conjugates.

Although multivalent glycosidase inhibitors have shown enhanced glycosidase inhibition activities, further applications and research directions need to be developed in the future. In this paper, two positional isomeric perylene bisimide derivatives ( and ) with 1-deoxynojirimycin conjugated were synthesized. Furthermore, and showed positional isomeric effects on the optical properties, self-assembly behaviors, glycosidase inhibition activities, and hypoglycemic effects.

Publisher Correction: Harnessing the intracellular triacylglycerols for titer improvement of polyketides in Streptomyces.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Harnessing the intracellular triacylglycerols for titer improvement of polyketides in Streptomyces.

Pharmaceutically important polyketides such as avermectin are mainly produced as secondary metabolites during the stationary phase of growth of Streptomyces species in fermenters. The source of intracellular metabolites that are funneled into polyketide biosynthesis has proven elusive. We applied multi-omics to reveal that intracellular triacylglycerols (TAGs), which accumulates in primary metabolism, are degraded during stationary phase.

Transcriptional Regulator AcrR Increases Ethanol Tolerance through Regulation of Fatty Acid Synthesis in .

is a versatile bacterium with significant adaptability to harsh habitats containing excessive ethanol concentrations. It was found that the NF92-TetR/AcrR family regulator, AcrR, significantly enhanced the growth rate of this lactic acid bacterium in the presence of ethanol. Through screening 172 ethanol-resistant related genes by electrophoretic mobility shift and quantitative reverse transcription-PCR (RT-qPCR) assays, six genes were identified to be regulated by AcrR under ethanol stress.

A novel family of intrinsic chloramphenicol acetyltransferase CATC in Vibrio parahaemolyticus: Naturally occurring variants reveal diverse resistance levels against chloramphenicol.

Intrinsic resistance of bacteria to antibiotics plays an increasingly significant role in antibiotic resistance. However, the breadth of intrinsic resistance has not been fully elucidated. Here we identified a novel class of chloramphenicol acetyltransferase (type C CAT or CATC) in Vibrio parahaemolyticus and its closely related species V.

Photobacterium sp. NNA4, an efficient hydroxylamine-transforming heterotrophic nitrifier/aerobic denitrifier.

An efficient heterotrophic nitrifying/aerobic denitrifying strain, Photobacterium sp. NNA4 was isolated from a recirculating aquaculture system (RAS). NNA4 was capable of utilizing ammonia, nitrate or nitrite as sole N-source with maximal removal rates of 12.

Transcriptome responses of Lactobacillus acetotolerans F28 to a short and long term ethanol stress.

Lactobacillus acetotolerans is a major microbe contributing to the Chinese liquor fermentation with unknown function. It can be grown well in a high concentration of ethanol. RNA sequencing (RNA-seq) was performed on L.

Engineered jadomycin analogues with altered sugar moieties revealing JadS as a substrate flexible O-glycosyltransferase.

Glycosyltransferases (GTs)-mediated glycodiversification studies have drawn significant attention recently, with the goal of generating bioactive compounds with improved pharmacological properties by diversifying the appended sugars. The key to achieving glycodiversification is to identify natural and/or engineered flexible GTs capable of acting upon a broad range of substrates. Here, we report the use of a combinatorial biosynthetic approach to probe the substrate flexibility of JadS, the GT in jadomycin biosynthesis, towards different non-native NDP-sugar substrates, enabling us to identify six jadomycin B analogues with different sugar moieties.

A new subclass of intrinsic aminoglycoside nucleotidyltransferases, ANT(3")-II, is horizontally transferred among Acinetobacter spp. by homologous recombination.

The emergence and spread of antibiotic resistance among Acinetobacter spp. have been investigated extensively. Most studies focused on the multiple antibiotic resistance genes located on plasmids or genomic resistance islands.

Structure and Function of a C-C Bond Cleaving Oxygenase in Atypical Angucycline Biosynthesis.

C-C bond ring cleaving oxygenases represent a unique family of enzymes involved in the B ring cleavage reaction only observed in atypical angucycline biosynthesis. B ring cleavage is the key reaction leading to dramatic divergence in the final structures of atypical angucyclines. Here, we present the crystal structure of AlpJ, the first structure of this family of enzymes.

Heterologous expression of oxytetracycline biosynthetic gene cluster in Streptomyces venezuelae WVR2006 to improve production level and to alter fermentation process.

Heterologous expression is an important strategy to activate biosynthetic gene clusters of secondary metabolites. Here, it is employed to activate and manipulate the oxytetracycline (OTC) gene cluster and to alter OTC fermentation process. To achieve these goals, a fast-growing heterologous host Streptomyces venezuelae WVR2006 was rationally selected among several potential hosts.