Trophic interaction of the aerotolerant anaerobe Clostridium intestinale and the acetogen Sporomusa rhizae sp. nov. isolated from roots of the black needlerush Juncus roemerianus

Abstract

Acetogens were enumerated from root homogenates of the black needlerush Juncus roemerianus obtained from a nearly pristine salt marsh. An isolated colony, ST1, yielded acetogenic activity and was initially thought to be a pure culture; however, ST1 was subsequently found to be composed of an aerotolerant fermentative anaerobe (RC) and an acetogen (RST) (T indicates type strain). The two spore-forming mesophiles were separated by selective cultivation under conditions favouring the growth of either RC or RST. The 16S rRNA gene sequence of RC was 99 % similar to that of Clostridium intestinale, indicating that RC was a new isolate of this clostridial species. The rRNA gene sequence most similar to that of RST was only 96 % similar to that of RST and was from a species of the acetogenic genus Sporomusa, indicating that RST was a new sporomusal species; the name Sporomusa rhizae sp. nov. is proposed. RC grew at the expense of saccharides. H2-forming butyrate fermentation was the primary catabolism utilized by RC under anoxic conditions, while homolactate fermentation was the primary catabolism under oxic conditions. RC consumed O2 and tolerated 20 % O2 in the headspace of shaken broth cultures. In contrast, RST was acetogenic, utilized H2, lactate and formate, did not utilize saccharides, and could not tolerate high concentrations of O2. RST grew by trophic interaction with RC on saccharides via the uptake of H2, and, to a lesser extent, lactate and formate produced by RC. Co-cultures of the two organisms yielded high amounts of acetate. These results indicate that (i) previously uncharacterized species of Sporomusa are associated with Juncus roots and (ii) trophic links to O2-consuming aerotolerant anaerobes might contribute to the in situ activities and survival strategies of acetogens in salt marsh rhizospheres, a habitat subject to gradients of plant-derived O2.

Isolation and characterization of a hydrogen- and ethanol-producing Clostridium sp. strain URNW

“…The newly identified Clostridium sp. strain URNW is a mesophilic bacterium that has the ability to synthesize H 2 at a rate that is comparable with those of the mesophilic, saccharophilic, butyrate-producing bacteria C. acetobutylicum (Peguin and Soucaille 1995;Zhang et al 2006) and C. butyricum (Chen et al 2005); the mesophilic, acetateproducing bacteria C. termitidis (Ramachandran et al 2008) and Clostridium cellulolyticum (Desvaux et al 2000); and the aerotolerant, butyrate-producing bacterium C. intestinale (Gössner et al 2006). Unlike the acetate-producing bacteria C. termitidis and C. cellulolyticum, which have doubling times of 6.9 h (Ramachandran et al 2008) and 7 h (Giallo et al 1983) on cellobiose, respectively, Clostridium sp.…”

“…The type strain of C. intestinale ATCC 49213 was isolated from cattle faeces, but no metabolic end-product data are available (Lee et al 1989). An aerotolerant, rhizospheric strain of C. intestinale RC AM158323 was shown to synthesize butyrate and H 2 under anoxic conditions, and the production of butyrate was enhanced by the presence of other H 2 -utilizing bacteria, such as Sporomusa rhizae, in cocultures (Gössner et al 2006). The major end-products of C. intestinale RC AM158323 on cellobiose and glucose were acetate, butyrate, lactate, formate, and H 2 , but ethanol production was absent (Gössner et al 2006).…”

“…The butyrate-producing, aerotolerant, mesophilic C. intestinale AM158323 strain produced H 2 at 16.6 and 10.9 mmolÁL -1 from an initial substrate concentration of 5 mmolÁL -1 cellobiose and glucose, respectively (Gössner et al 2006). During the batch fermentation of C. butyricum CGS5 on 17.8 g sucroseÁL -1 at pH 6.0, H 2 evolution was observed only after mid-exponential phase (14-16 h), with a maximum H 2 production rate (219 mLÁh -1 ÁL -1 ) obtained during stationary phase (Chen et al 2005).…”

Effect of temperature change on the composition of the bacterial and archaeal community potentially involved in the turnover of acetate and propionate in methanogenic rice field soil

“…These two microorganisms formed a consortium in which the C. intestinale degraded saccharides and produced H 2 , lactate and formate, which were then used by S. rhizae , which by itself is unable to degrade saccharides but can degrade the fermentation products of C. intestinale . This consortium was found to produce acetate under anoxic conditions and consume acetate under oxic conditions (Gössner et al , 2006). Hence, it might be possible that members of the family Acidaminococcaceae are involved in syntrophic acetate oxidation.…”

Response of the Microaerophilic Bifidobacterium Species, B. boum and B. thermophilum , to Oxygen

“…Although anaerobes are defined as being unable to grow in the presence of O 2 , their degree of O 2 sensitivity exhibits wide variation (2,3,10,11,14,15,16,17,18,20,21,25,28). The genus Bifidobacterium is a well-investigated anaerobe known to be beneficial to human health.…”