Open Access Articles- Top Results for Poribacteria


Poribacteria are a candidate phylum of bacteria originally identified in the microbiome of sea sponges (Porifera). Poribacteria were distinguished from other microorganisms associated with sea sponges by their distinctive morphology featuring a large membrane-bound cellular compartment that frequently contains DNA, a highly unusual feature for a prokaryote.[1] Poribacteria are Gram-negative mixotrophs.[2]


Single-cell genomics analysis of poribacteria reveals a genome with a lower size bound of 1.88 megabases and 1585 protein-coding genes, of which an unusually high 24% have no homology to known genes. Among the genes of identifiable homology, genetic infrastructure can be identified for aerobic metabolism, denitrification and urea uptake, and carbon fixation through the Wood-Ljungdahl pathway.[2]

The poribacterial genome is also reported to contain an unusually high number of phyH-domain proteins, which are enzymes involved in oxidative reactions. The functional significance of this observation is not known.[3]

Cell compartmentalization

Cell compartmentalization into distinct membrane-bound organelles is a universal and defining property of eukaryotes, but had not been not observed in prokaryotes other than the Planctomycetes before the identification of Poribacteria.[1] The distinctive poribacterial compartments were originally identified using fluorescence in situ hybridization and electron microscopy and were found to frequently, but not always, contain DNA.[1] Genomic evidence reveals the presence of proteins associated with compartmentalization, but not of membrane coat proteins.[3]

Eukaryote-like proteins

Genomic analyses of poribacteria reveal several families of cell-surface repeat proteins that resemble those found in eukaryotes, and are infrequently found in prokaryotes. Examples include ankyrin and leucine-rich repeat domains,[2] as well as tetratricopeptides.[3] Unusual low-density lipoprotein receptor repeat proteins are also found, of unknown function. Most of these protein families are thought to be involved in surface interactions with the sponge host.[3]

In addition, genetic infrastructure for sterol biosynthesis is observed in poribacterial genomes, otherwise found almost exclusively in eukaryotes and the planctomycete Gemmata obscuriglobus.[2]

Ecological niche

Poribacteria are symbionts of sea sponges, among the most abundant microorganisms in the highly diverse microbiome of the sponge mesohyl.[2] They have been found in a large variety of sponge species from diverse geographic origins.[4] The distribution of microorganisms in the sponge microbiome can be vertically inherited, with adult sponges transmitting their distinctive microbial communities to offspring.[5]


  1. ^ a b c Fieseler, L; Horn, M; Wagner, M; Hentschel, U (June 2004). "Discovery of the novel candidate phylum "Poribacteria" in marine sponges.". Applied and environmental microbiology 70 (6): 3724–32. PMID 15184179. 
  2. ^ a b c d e Siegl, A; Kamke, J; Hochmuth, T; Piel, J; Richter, M; Liang, C; Dandekar, T; Hentschel, U (January 2011). "Single-cell genomics reveals the lifestyle of Poribacteria, a candidate phylum symbiotically associated with marine sponges.". The ISME journal 5 (1): 61–70. PMID 20613790. 
  3. ^ a b c d Kamke, J; Rinke, C; Schwientek, P; Mavromatis, K; Ivanova, N; Sczyrba, A; Woyke, T; Hentschel, U (2014). "The candidate phylum Poribacteria by single-cell genomics: new insights into phylogeny, cell-compartmentation, eukaryote-like repeat proteins, and other genomic features.". PloS one 9 (1): e87353. PMID 24498082. 
  4. ^ Lafi, FF; Fuerst, JA; Fieseler, L; Engels, C; Goh, WW; Hentschel, U (September 2009). "Widespread distribution of poribacteria in demospongiae.". Applied and environmental microbiology 75 (17): 5695–9. PMID 19561181. 
  5. ^ Schmitt, S; Angermeier, H; Schiller, R; Lindquist, N; Hentschel, U (December 2008). "Molecular microbial diversity survey of sponge reproductive stages and mechanistic insights into vertical transmission of microbial symbionts.". Applied and environmental microbiology 74 (24): 7694–708. PMID 18820053.