Molecular diversity of phototrophic biofilms on building stone

Abstract

Composition and diversity of aeroterrestrial phototrophic microbial communities are up to now poorly understood. Here, we present a comparative study addressing the composition of algal communities on sandstone substrata based upon the analysis of rRNA gene clone libraries from environmental samples and crude cultures. From a west-facing, shaded wall area of the mediaeval castle ruin Gleichen (Thuringia, Germany), sequences mainly related to the green algae Prasiococcus and Trebouxia (Trebouxiophyceae) were retrieved. A south-west-facing, sun-exposed wall area was mainly colonized by Apatococcus and a Phyllosiphon-related alga. Just a few species, in particular Stichococcus-related strains, were ubiquitous in both areas. Samples from a basement vault exposed to low irradiance exhibited Chlorophyceae like Chromochloris and Bracteacoccus. Thus, most green algae on the daylight-exposed walls were affiliated to Trebouxiophyceae, whereas Chlorophyceae were dominant in samples taken from the site kept under low irradiance. Accordingly, cyanobacterial communities were different: the sun-exposed area was dominated by Synechococcus-related organisms, while on the shaded wall area, cyanobacteria were almost absent. The filamentous Leptolyngbya dominated samples from the basement vault. Scanning electron microscopy revealed endolithic algal morphotypes (coccoid algae and diatoms) dominant in open pores between mineral particles. Here, the organisms may be also involved in biogenic weathering of stone.

Molecular diversity of green corticolous microalgae from two sub-Mediterranean European localities

“…Many Chlorophyceae recorded from terrestrial microhabitats are characteristic members of soil surface crust communities (Lewis & Flechtner, 2002;Büdel et al, 2009;Flechtner et al, 2013). We assume that most terrestrial chlorophyceans are better adapted to relatively high irradiation levels than members of the Trebouxiophyceae, which typically dominate in more shaded microhabitats, such as on tree bark and inside buildings (Hallmann et al, 2013).…”

“…Kalinella apyrenoidosa, one of the two species of the genus Kalinella, was recently described from a sub-Mediterranean corticolous sample (Neustupa et al, 2013a). The life cycle of a peculiar and little-known genus Phyllosiphon, another member of the Watanabea clade, probably includes chlorelloid subaerial individuals, as well as siphonaceous parasitic populations thriving in the leaves of the subtropical vascular plant genus Arisarum (Aboal & Werner, 2011;Hallmann et al, 2013).…”

Community succession of bacteria and eukaryotes in dune ecosystems of Gurbantünggüt Desert, Northwest China

“…Among the classified Chlorophyta, sequences of the order Trebouxiophyceae were most abundant, which are also known to be dominant on building facades and other crusts Fig. 2 Relative abundance of cyanobacterial sequences at genus level to total cyanobacteral sequences in each bacterial and cyanobacteial library (%) (Büdel et al 2009;Hallmann et al 2013). Most green algae of Trebouxiophyceae can synthesize high concentrations of anti-stress metabolites, which could act as antioxidants, heat protectants (protein stabilizers), and rapidly available respiratory substrates (Karsten et al 2010).…”

Cryptogam covers on sepulchral monuments and re-colonization of a marble surface after cleaning

“…In a second approach, the samples were first amplified with 20F/18L and in a second round (semi-nested PCR) with 20F and the green algal-specific primer CH1750R (5 0 CTTCCTCTAGRTGGGAGG 3 0 ; Hallmann et al 2013). About 30 ng of the extracted DNA was used as template.…”