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Environmental actinorhodopsin expression revealed by a new in situ filtration and fixation sampler
Author(s) -
Wurzbacher Christian,
Salka Ivette,
Grossart HansPeter
Publication year - 2012
Publication title -
environmental microbiology reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.229
H-Index - 69
ISSN - 1758-2229
DOI - 10.1111/j.1758-2229.2012.00350.x
Subject(s) - actinobacteria , biology , bacterioplankton , aquatic ecosystem , ecology , metagenomics , ecosystem , gene , evolutionary biology , genetics , phytoplankton , nutrient , 16s ribosomal rna
Summary Freshwater Actinobacteria are an important and dominant group of bacterioplankton in most temperate freshwater systems. Recently, metagenomic studies discovered rhodopsin‐like protein‐coding sequences present in Actinobacteria which could be a decisive hint for their success in freshwater ecosystems. We analysed the diversity of actinorhodopsin (ActR) in Lake Stechlin (northern Germany) and assessed the actR expression profile during a diurnal cycle. We obtained 85 positive actR clones which could be subsequently grouped to 17 operational taxonomic units assuming a 90% sequence similarity. The phylogenetic analysis points to a close relationship of all obtained sequences to the acI lineage of Actinobacteria , forming six independent clusters. For the first time, we followed in situ transcription of actR in Lake Stechlin revealing a rather constitutive circadian gene expression. For analysing in situ expression patterns of functional genes in aquatic ecosystems, such as actR , we invented a new in situ filtration and fixation sampler (IFFS). The IFFS enables the representative investigation of microbial transcriptomes in any aquatic ecosystem at all water depths. The IFFS sampler is simple and inexpensive, and we provide all engineering plans for an easy rebuild. Consequently, our IFFS is suitable to reliably study expression of any known functional gene of any aquatic microorganism.