Gracilibacteria

{{Short description|Phylum of bacteria}}

{{Taxobox

|name = Gracilibacteria

|image =

|image_caption =

|domain = Bacteria

|unranked_phylum = CPR group

|phylum = "Gracilibacteria"

|phylum_authority = Rinke et al. 2013

|genus = "Ca. Altimarinus"

|type_species = "Ca. A. pacificus"

|type_species_authority = Rinke et al. 2013

}}

Gracilibacteria is a bacterial candidate phylum formerly known as GN02, BD1-5, or SN-2. It is part of the Candidate Phyla Radiation and the Patescibacteria group.

The first representative of the Gracilibacteria phylum was reported in 1999 after being recovered from a deep-sea sediment sample. The representative 16S rRNA sequence was referred to as "BD1-5" (sample BD1, sequence 5) and while it was noted that it displayed low sequence identity to any known 16S rRNA gene, it was not proposed as a new phylum at this time.{{Cite journal|last1=Li|first1=Lina|last2=Kato|first2=Chiaki|last3=Horikoshi|first3=Koki|date=1999-05-01|title=Bacterial diversity in deep-sea sediments from different depths|journal=Biodiversity & Conservation|language=en|volume=8|issue=5|pages=659–677|doi=10.1023/A:1008848203739|s2cid=25820840|issn=1572-9710}} In 2006, representatives of Gracilibacteria were recovered from a hypersaline microbial mat from Guerrero Negro, Baja California Sur, Mexico and proposed as a new phylum "GN02".{{Cite journal|last1=Ley|first1=Ruth E.|last2=Harris|first2=J. Kirk|last3=Wilcox|first3=Joshua|last4=Spear|first4=John R.|last5=Miller|first5=Scott R.|last6=Bebout|first6=Brad M.|last7=Maresca|first7=Julia A.|last8=Bryant|first8=Donald A.|last9=Sogin|first9=Mitchell L.|last10=Pace|first10=Norman R.|date=2006-05-01|title=Unexpected Diversity and Complexity of the Guerrero Negro Hypersaline Microbial Mat|journal=Applied and Environmental Microbiology|language=en|volume=72|issue=5|pages=3685–3695|doi=10.1128/AEM.72.5.3685-3695.2006|issn=0099-2240|pmid=16672518|pmc=1472358|bibcode=2006ApEnM..72.3685L}} The name "Gracilibacteria" was proposed for the BD1-5/GN02 lineage in 2013, based on a substantial expansion of the genomic representation of this phylum.{{Cite journal|last1=Sieber|first1=Christian M. K.|last2=Paul|first2=Blair G.|last3=Castelle|first3=Cindy J.|last4=Hu|first4=Ping|last5=Tringe|first5=Susannah G.|last6=Valentine|first6=David L.|last7=Andersen|first7=Gary L.|last8=Banfield|first8=Jillian F.|date=2019-11-12|title=Unusual Metabolism and Hypervariation in the Genome of a Gracilibacterium (BD1-5) from an Oil-Degrading Community|journal=mBio|volume=10|issue=6|doi=10.1128/mbio.02128-19|pmid=31719174|pmc=6851277|issn=2150-7511}}{{Cite journal|last1=Rinke|first1=Christian|last2=Schwientek|first2=Patrick|last3=Sczyrba|first3=Alexander|last4=Ivanova|first4=Natalia N.|last5=Anderson|first5=Iain J.|last6=Cheng|first6=Jan-Fang|last7=Darling|first7=Aaron|last8=Malfatti|first8=Stephanie|last9=Swan|first9=Brandon K.|last10=Gies|first10=Esther A.|last11=Dodsworth|first11=Jeremy A.|date=July 2013|title=Insights into the phylogeny and coding potential of microbial dark matter|journal=Nature|language=en|volume=499|issue=7459|pages=431–437|doi=10.1038/nature12352|pmid=23851394|bibcode=2013Natur.499..431R|issn=1476-4687|doi-access=free|hdl=10453/27467|hdl-access=free}}

The first Gracilibacteria genome was recovered from an acetate-amended aquifer (Rifle, CO, USA) using culture-independent, genome-resolved metagenomic techniques in 2012.{{Cite journal|last1=Wrighton|first1=K. C.|last2=Thomas|first2=B. C.|last3=Sharon|first3=I.|last4=Miller|first4=C. S.|last5=Castelle|first5=C. J.|last6=VerBerkmoes|first6=N. C.|last7=Wilkins|first7=M. J.|last8=Hettich|first8=R. L.|last9=Lipton|first9=M. S.|last10=Williams|first10=K. H.|last11=Long|first11=P. E.|date=2012-09-27|title=Fermentation, Hydrogen, and Sulfur Metabolism in Multiple Uncultivated Bacterial Phyla|journal=Science|volume=337|issue=6102|pages=1661–1665|doi=10.1126/science.1224041|pmid=23019650|bibcode=2012Sci...337.1661W|s2cid=10362580|issn=0036-8075}} Genomic analyses suggest that members of the Gracilibacteria phylum have limited metabolisms and are likely symbionts or endosymbionts. Members of Gracilibacteria use an alternative genetic code in which UGA encodes the glycine amino acid instead of a stop codon{{Cite journal|last1=Hanke|first1=Anna|last2=Hamann|first2=Emmo|last3=Sharma|first3=Ritin|last4=Geelhoed|first4=Jeanine S.|last5=Hargesheimer|first5=Theresa|last6=Kraft|first6=Beate|last7=Meyer|first7=Volker|last8=Lenk|first8=Sabine|last9=Osmers|first9=Harald|last10=Wu|first10=Rong|last11=Makinwa|first11=Kofi|date=2014-05-16|title=Recoding of the stop codon UGA to glycine by a BD1-5/SN-2 bacterium and niche partitioning between Alpha- and Gammaproteobacteria in a tidal sediment microbial community naturally selected in a laboratory chemostat|journal=Frontiers in Microbiology|volume=5|page=231|doi=10.3389/fmicb.2014.00231|pmid=24904545|pmc=4032931|issn=1664-302X|doi-access=free}}