Clonothrix fuscaRoze 1896, a Filamentous, Sheathed, Methanotrophic γ-Proteobacterium

Abstract

Crenothrix polyspora Cohn 1870 and Clonothrix fusca Roze 1896 are two filamentous, sheathed microorganisms exhibiting complex morphological differentiation, whose phylogeny and physiology have been obscure for a long time due to the inability to cultivate them. Very recently, DNA sequencing data from uncultured C. polyspora-enriched material have suggested that Crenothrix is a methane-oxidizing ␥-proteobacterium (39). In contrast, the possible ecological function of C. fusca, originally considered a developmental stage of C. polyspora, is unknown. In this study, temporal succession of two filamentous, sheathed microorganisms resembling Cohn's Crenothrix and Roze's Clonothrix was observed by analyzing the microbial community of an artesian well by optical microscopy. Combined culture-based and culture-independent approaches enabled us to assign C. fusca to a novel subgroup of methane-oxidizing ␥-proteobacteria distinct from that of C. polyspora. This assignment was supported by (i) methane uptake and assimilation experiments, (ii) ultrastructural data showing the presence in C. fusca cytoplasm of an elaborate membrane system resembling that of methanotrophic ␥-proteobacteria, and (iii) sequencing data demonstrating the presence in its genome of a methanol dehydrogenase ␣ subunit-encoding gene (mxaF) and a conventional particulate methane mono-oxygenase ␣ subunit-encoding gene (pmoA) that is different from the unusual pmoA (u-pmoA) of C. polyspora.

Active methylotrophs in the sediments of Lonar Lake, a saline and alkaline ecosystem formed by meteor impact

“…Methanotrophs are a specialized group of methylotrophs that use methane as the sole carbon and energy source. These are distributed among Gammaproteobacteria (type I methanotrophs), Alphaproteobacteria (type II methanotrophs) (reviewed in Trotsenko and Murrell, 2008), filamentous methane oxidizers (Stoecker et al, 2006;Vigliotta et al, 2007) and Verrucomicrobia (Dunfield et al, 2007;Pol et al, 2007;Islam et al, 2008). Methanotrophs oxidize methane to methanol by the enzyme methane monooxygenase (MMO), present either as the particulate form (pMMO) in all characterized methanotrophs (except in the genus Methylocella (Dedysh et al, 2000)) or as the soluble form (sMMO) in some methanotrophs (Trotsenko and Murrell, 2008).…”

The impact of environmental perturbation on microbial community structure and dynamics: Factors affecting growth ofClonothrix fuscain groundwater

“…In December of 1936, both C. fusca and C. polyspora appeared in great quantity, often attached to the same mass substrate, during a period of unseasonably warm weather (Kolk 1938). Although a possible correlation between the growth of these microorganisms in the artesian well and an increase of iron, calcium, magnesium, ammonia and nitrite levels in the water with a moderate decrease of pH values was suggested in our previous study (Vigliotta et al 2007), the link between the physical-chemical environmental parameters and the physiology of this microorganism remained elusive. In this study we associate the absolute requirement of high magnesium and calcium levels for growth of C. fusca to the absence, among its membrane lipids, of cardiolipin, a dimeric phospholipid derived from phosphatidylglycerol, generally abundant in Proteobacteria membranes (Cronan & Gelmann 1975, Dowhan 1997).…”

“…coli and P. aeruginosa were cultivated in LuriaBertani (LB) Broth/Agar (DIFCO) at 378C in air atmosphere; growth of V. harveyi was carried out in Nutrient Broth/Agar (DIFCO) containing 3% NaCl at 308C in air atmosphere; N. meningitidis was cultivated in Gonococcal (GC) Broth/Agar with 1% Polyvitox, at 378C in 5% CO 2 incubator. The enrichment media for C. fusca were previously described (Vigliotta et al 2007). They were formulated using DSMZ medium 569 (www.dsmz.de/) that was diluted 1:5 (569-0.2X) as a base.…”

“…In a previous work temporal succession of two sheathed, filamentous microorganisms resembling Cohn's Crenothrix (Cohn 1870) and Roze's Clonothrix (Roze 1896) was observed by analyzing the microbial community of an artesian well by optical microscopy (Vigliotta et al 2007). Taking advantage of luxuriant growth of Clonothrix fusca in this environment, the problem of defining the taxonomy of this microorganism, originally considered a developmental stage of Crenothrix polyspora (Molisch 1910, Lieske 1922, Kolk 1938), a methanotrophic microorganism (Stoecker et al 2006), was also addressed.…”

“…Taking advantage of luxuriant growth of Clonothrix fusca in this environment, the problem of defining the taxonomy of this microorganism, originally considered a developmental stage of Crenothrix polyspora (Molisch 1910, Lieske 1922, Kolk 1938), a methanotrophic microorganism (Stoecker et al 2006), was also addressed. Combined culture-based and cultureindependent approaches enabled us to assign C. fusca to a novel subgroup of methane oxidizing g-Proteobacteria distinct from that of C. polyspora on the basis of physiological, ultrastructural and molecular data (Vigliotta et al 2007). …”