Search

Non-human primates harbor diverse microbiomes in their guts. As a part of China Microbiome Initiatives, we cultivated and characterized the gut microbiome of cynomolgus monkeys (Macaca fascicularis). In this report, we communicate the characterization and taxonomy of 8 bacterial strains that were obtained from fecal samples of captive cynomolgus monkeys. The results revealed that they represented 8 novel bacterial species. The proposed names of the 8 novel species are Alkaliphilus flagellate (type strain MSJ-5T =CGMCC 1.45007T=KCTC 15974T), Butyricicoccus intestinisimiae MSJd-7T (type strain MSJd-7T =CGMCC 1.45013T =KCTC 25112T), Clostridium mobile (type strain MSJ-11T =CGMCC 1.45009T=KCTC 25065T), Clostridium simiarum (type strain MSJ-4T =CGMCC 1.45006T =KCTC 15975T), Dysosmobacter acutus (type strain MSJ-2T =CGMCC 1.32896T=KCTC 15976T), Paenibacillus brevis MSJ-6T (type strain MSJ-6T =CGMCC 1.45008T=KCTC 15973T), Peptoniphilus ovalis (type strain MSJ-1T =CGMCC 1.31770T=KCTC 15977T), and Tissierella simiarum (type strain MSJ-40T =CGMCC 1.45012T=KCTC 25071T).

Hydroxylamine is a key intermediate of microbial ammonia oxidation and plays an important role in the biogeochemical cycling of N-compounds. Hydroxylamine is oxidized to NO or N2O by hydroxylamine oxidases or cytochrome P460 from heterotrophic or autotrophic bacteria, but its enzymatic oxidation to N2 has not yet been observed. Here, we report on the discovery of a novel oxidase that converts hydroxylamine to N2 from the newly isolated heterotrophic nitrifier Alcaligenes strain HO-1. Strain HO-1 accumulated hydroxylamine and produced N2 from ammonia oxidation. Using transcriptome analysis and heterologous expression via fosmid library screening, we identified three genes (dnfABC) of strain HO-1 that enabled E. coli cells not only to produce hydroxylamine from 15N-labelled ammonium but also to further convert it to 15N2. The three genes were individually cloned and expressed, and their translational products DnfA, DnfB, and DnfC were purified. In vitro DnfA bound to hydroxylamine and catalyzed the conversion of hydroxylamine to N2 in the presence of FAD, NADH and O2. Thus, DnfA was identified as a novel hydroxylamine oxidase and catalyzed a previously unknown N-N bond forming reaction with a yet-to-be discovered mechanism. DnfA homologs were detected in different bacterial groups, suggesting that hydroxylamine oxidation to nitrogen might occur in additional microbial taxa.