Vilhelmsson, O. | Search bioRxiv

bioRxiv2018

Xylanolytic psychrotrophs from andosolic sedge fens and moss heaths in Iceland

Nine xylanolytic bacterial strains were isolated from fen and heath soils in northern Iceland. They were found by 16S rRNA gene sequencing to belong to the genera Paenibacillus, Bacillus, Pseudomonas, and Stenotrophomonas. Using a simple, plate-based semiquantitative assay with azo-crosslinked xylan as the substrate, it was determined that although isolated from cold environments, most of the strains displayed greater xylanolytic activity under mesophilic conditions, with only the paenibacilli displaying markedly cold-active xylanolytic activity. Indeed, for one isolate, Paenibacillus castaneae OV2122, xylanolytic activity was only detected at 15{degrees}C and below under the conditions tested. Of the nine strains, Paenibacillus amylolyticus OV2121 displayed the greatest activity at 5{degrees}C. Glycohydrolase family-specific PCR indicated that the paenibacilli produced multiple xylanases of families 10 and 11, whereas a family 8 xylanase was detected in Pseudomonas kilonensis AL1515, and a family 11 xylanase in Stenotrophomonas rhizophila AL1610.

microbiology↗

bioRxiv2018

Gas seepage pockmark microbiomes suggest the presence of sedimentary coal seams in the Oxarfjordur graben of NE-Iceland

Natural gas seepage pockmarks are found off and onshore in the Oxarfjorthur graben, NE Iceland. The bacterial communities of two onshore seepage sites were analysed by amplicon sequencing of 16S rDNA, along with determining the geochemical characteristics, hydrocarbon content and the carbon isotope composition of the sites.\n\nWhile one site was found to be characterised by biogenic origin of methane gas, with carbon isotope ratio {delta}13C [{per thousand}] = -63.2, high content of organic matter and complex hydrocarbons, the other site showed a mixed origin of the methane gas ({delta}13C [{per thousand}] = -26.6) with geothermal characteristics and lower organic matter content. While both sites harboured Proteobacteria as the most abundant bacterial phyla, the Deltaproteobacteria were more abundant at the geothermal site, and the Alphaproteobacteria at the biogenic site. The Dehalococcoidia class of the Chloroflexi phylum was abundant at the geothermal site while the Anaerolineae class was more abundant at the biogenic site. Bacterial strains from the seepage pockmarks were isolated on a variety of selective media targeting bacteria with bioremediation potential. A total of 106 strains were isolated and characterised, including representatives from the phyla Proteobacteria, Bacterioidetes, Firmicutes, and Actinobacteria. This article describes the first microbial study on gas seepage pockmarks in Iceland.

microbiology↗