Sediment microbes of deep-sea bioherms on the northwest shelf of Australia

Bacterial communities in sediment of a Mediterranean marine protected area

Biodiversity is crucial in preservation of ecosystems, and bacterial communities play an indispensable role for the functioning of marine ecosystems. The Mediterranean marine protected area (MPA) “Capo Gallo–Isola delle Femmine” was instituted to preserve marine biodiversity. The bacterial diversity associated with MPA sediment was compared with that from sediment of an adjacent harbour exposed to intense nautical traffic. The MPA sediment showed higher diversity with respect to the impacted site. A 16S rDNA clone library of the MPA sediment allowed the identification of 7 phyla: Proteobacteria (78%), Firmicutes (11%), Acidobacteria (3%), Actinobacteria (3%), Bacteroidetes (2%), Planctomycetes (2%), and Cyanobacteria (1%). Analysis of the hydrocarbon (HC)-degrading bacteria was performed using enrichment cultures. Most of the MPA sediment isolates were affiliated with Gram-positive G+C rich bacteria, whereas the majority of taxa in the harbour sediment clustered with Alpha- and Gammaproteobacteria; no Gram-positive HC degraders were isolated from the harbour sediment. Our results show that protection probably has an influence on bacterial diversity, and suggest the importance of monitoring the effects of protection at microbial level as well. This study creates a baseline of data that can be used to assess changes over time in bacterial communities associated with a Mediterranean MPA.

Tateyamaria pelophila sp. nov., a facultatively anaerobic alphaproteobacterium isolated from tidal-flat sediment, and emended descriptions of the genus Tateyamaria and of Tateyamaria omphalii

A Gram-negative motile rod, strain SAM4T, was isolated from the highest positive dilution of a most probable number series inoculated with tidal-flat sediments from the German North Sea coast. The isolate grew at 4-35 degrees C and showed constant growth yields throughout almost the whole temperature range. Growth was observed between pH 6 and 9 and at salinities of 0.3-10.2%. Strain SAM4T required Na+ for growth, contained bacteriochlorophyll a and was catalase- and oxidase-positive. It was nutritionally versatile growing on a variety of carbon compounds including carbohydrates, amino acids and organic acids like lactate or succinate. It grew anaerobically on complex media such as marine broth, indicating fermentation, and by reducing trimethylammonium oxide. The dominant phospholipids were phosphatidylethanolamine and phosphatidylglycerol, whereas only traces of phosphatidylcholine and an unidentified lipid were found. The major fatty acid was n-C18:1omega7c. The DNA G+C content was 56.4 mol%. The isolate was identified as a member of the Roseobacter clade within the class Alphaproteobacteria. However, based on phylogenetic, phenotypic and physiological data, it clearly differs from its closest relative Tateyamaria omphalii. Therefore, a novel species is proposed: Tateyamaria pelophila sp. nov., with strain SAM4T (=DSM 17270T=LMG 23018T) as the type strain. Emended descriptions of the genus Tateyamaria and of Tateyamaria omphalii are also presented.

Microbial diversity in biofilms from corroding heating systems

Culture-independent investigations of the bacterial diversity and activity in district heating systems with and without corrosion did not make it possible to relate one group of microorganisms with the observed corrosion. Fluorescence in situ hybridization by oligonucleotide probes revealed the dominance of beta-proteobacteria, sulphate reducing prokaryotes and alpha-proteobacteria. Analysis of a clone library from one Danish heating (DH) system showed that the most sequences formed two clusters within the alpha-proteobacteria affiliated to the families Rhizobiaceae and Acetobacteraceae and two clusters within the beta-proteobacteria belonging to the family Comamonadaceae. Functional groups were determined by microautoradiography showing aerobic and anaerobic bacteria (sulphate reducing and methanogenic bacteria). The corrosion study showed that pitting corrosion rates were five to ten times higher than the general corrosion rates, suggesting the presence of biocorrosion. The results indicate that several bacterial groups could be involved in corrosion of DH system piping including sulphate reducing prokaryotes, Acidovorax (within the beta-proteobacteria), methanogenic bacteria and others.

Bacterial Diversity in Spent Mushroom Compost Assessed by Amplified rDNA Restriction Analysis and Sequencing of Cultivated Isolates

Spent mushroom compost (SMC) is the residual by-product of commercial Agaricus spp. cultivation, and it is mainly composed of a thermally treated cereal straw/animal manure mixture colonized by the fungal biomass. Research on the valorization of this material is mainly focusing on its use as soil conditioner and plant fertilizer. An investigation of the bacterial diversity in SMC was performed using molecular techniques in order to reveal the origin of SMC microflora and its potential effect on soil microbial communities after incorporation into agricultural soils. The bacterial population was estimated by the plate count method to a mean of 2.7 10(9) colony forming units (cfu) per g of dry weight, while the numbers of Gram-positive and Gram-negative bacteria were 1.9 10(9) and 4.9 10(8) cfu per g dw respectively as estimated by enumeration on semi-selective media. Fifty bacterial isolates were classified into 14 operational taxonomic units (OTUs) following ARDRA-PCR of the 16S rDNA gene. Sequencing of the 16S rDNA amplicon assigned 12 of the 14 OTUs to Gram-positive bacteria, associated with the genera Bacillus, Paenibacillus, Exiguobacterium, Staphylococcus, Desemzia, Carnobacterium, Brevibacterium, Arthrobacter and Microbacterium of the bacterial divisions Firmicutes and Actinobacteria. Two bacterial groups have phylogenetic links with the genera Comamonas and Sphingobacterium, which belong to beta-Proteobacteria and Bacteroidetes respectively. Two potentially novel bacteria are reported, which are associated with the genera Bacillus and Microbacterium. Most of the bacteria identified are of environmental origin, while strains related to species usually isolated from insects, animal and clinical sources were also detected. It appears that bacterial diversity in SMC is greatly affected by the origin of the initial material, its thermal pasteurization treatment and the potential unintended colonization of the mushroom substrate during the cultivation process.