Project description:The nitrogen rich compound guanidine occurs widely in nature and is used by microbes as a nitrogen source, but microorganisms that grow on guanidine have not yet been discovered. Here we show that complete ammonia-oxidizing microbes (comammox), but no other known nitrifiers, encode homologues of a guanidinase and that the comammox isolate Nitrospira inopinata grows on guanidine as sole source of energy and reductant. Proteomics, kinetic enzyme characterization, and the crystal structure of the N. inopinata guanidinase homologue demonstrated that it is a bona fide guanidinase. Transcription of comammox guanidinases was induced in wastewater treatment plant microbiomes upon incubation with guanidine, and guanidine degradation was detected in these systems. The discovery of guanidine as a selective growth substrate for comammox shows a unique niche of these globally important nitrifiers and offers new options for their isolation as well as for targeted manipulation of nitrifier communities.
Project description:Metagenome data from soil samples were collected at 0 to 10cm deep from 2 avocado orchards in Channybearup, Western Australia, in 2024. Amplicon sequence variant (ASV) tables were constructed based on the DADA2 pipeline with default parameters.
Project description:Metagenome sequencing All specimens were collected and immediately stored in a -80 freezer. All BALF samples were subjected to MS. DNA was extracted from BALF using the TIANamp Micro DNA kit (DP316, Tiangen Biotech). DNA libraries were constructed with the end-repair method and then sequenced on the BGI Sequencer platform (BGI Genomics, Shenzhen, China). Bioinformatic pipeline analysis Low-quality and short (<35 bp) reads were removed from raw data using fastp [10]. Remaining reads were mapped to the human reference genome (hg19) using the Burrows-Wheeler method to remove sequences of human origin. Filtered reads were classified with RefSeq, downloaded from NCBI (ftp://ftp.ncbi.nlm.nih.gov/genomes/).