Cluster formation in liverwort-associated methylobacteria and its implications

Abstract

Pink-pigmented methylotropic bacteria of the genus Methylobacterium inhabit the surfaces of plant organs. In bryophytes, these methylobacteria enhance cell growth, but the nature of this plant-microbe interaction is largely unknown. In this study, methylobacteria were isolated from the upper surface of the free-living thalli of the liverwort Marchantia polymorpha L. Identification of one strain by 16S ribosomal RNA (rRNA) gene-targeted polymerase chain reaction (PCR) and other data show that these microbes represent an undescribed species of the genus Methylobacterium (Methylobacterium sp.). The growth-promoting activity of these wild-type methylobacteria was tested and compared with that of the type strain Methylobacterium mesophilicum. Both types of methylobacteria stimulated surface expansion of isolated gemmae from Marchantia polymorpha by about 350%. When suspended in water, the liverwort-associated bacteria (Methylobacterium sp.) formed dense clusters of up to 600 cells. In liquid cultures of Methylobacterium mesophilicum, single cells were observed, but no clustering occurred. We suggest that the liverwort-associated methylobacteria are co-evolved symbionts of the plants: Cluster formation may be a behavior that enhances the survival of the epiphytic microbes during periods of drought of these desiccation-tolerant lower plants.

The core microbiome bonds the Alpine bog vegetation to a transkingdom metacommunity

“…For the first time, the microbiome composition was deeply studied for liverworts Bazzania trilobata and Mylia anomala. Despite a predominance of Alphaproteobacteria, some of which are known as symbionts of the liverwort Marchantia polymorpha L. (Kutschera et al 2007), we found a high diversity of other bacterial taxa and detected Cyanobacteria that were not previously reported for these liverworts genera (Adams & Duggan 2008).…”

Methylobacterium marchantiae sp. nov., a pink-pigmented, facultatively methylotrophic bacterium isolated from the thallus of a liverwort

“…Following isolation of a number of strains, we focused our attention on a pink-pigmented isolate designated in our laboratory as strain JT1 T . When maintained in liquid medium supplemented with methanol, the organism formed clusters of several hundred cells (Kutschera et al , 2007). This ‘crowding-effect’ was not detected in control populations of Methylobacterium mesophilicum DSM 1708 T (Austin & Goodfellow, 1979; Green & Bousfield, 1983).…”

“…In October 2003, we collected fragments of the common liverwort Marchantia polymorpha L. along moist areas of a stream in the mountains around Kassel, Germany (Bergpark Wilhelmshöhe, about 500 m above sea level, 51 u 199 N 9 u 249 E), with the aim of isolating epiphytic, pink-pigmented, facultatively methylotrophic bacteria and analysing their growth-promoting effect on sterile fragments of lower plants (Kutschera et al, 2007). The liverwort samples were stored under aseptic conditions and analysed in the laboratory.…”

Methylobacteria isolated from bryophytes and the 2-fold description of the same microbial species

“…However, the thalli of the liverwort Marchantia polymorpha, from which M. marchantiae strain JT1 T was isolated, were obtained from the moist regions along a waterfall in the Bergpark Wilhelmshöhe. 10,11 We suggest that Hoppe et al 5 assumed that we collected both bryophyte species in the same locality, the Bergpark Wilhelmshöhe, which is not correct. Thus, in the original description of isolate F3.2 (M. funariae Schauer and in this article 5 and provide novel information on the phylogenetic position, the type locality, and the correct cell size of this taxon.…”