Observation on the microbial incorporation of thymidine and leicine in marine sediments

The simultaneous incorporation of radiolabelled thymidine and leucine was followed in intact muddy sand sediments from the North Sea. As it could be shown, incorporation activities covaried over sediment depth. Parallel analysis of the enzymatic decomposition of organic material (by means of the hydrolysis of fluoresceindiacetate) revealed that stimulations of microbial biomass production coincided with stimulations of enzymatic activities although maxima of both processes occurred at different sediment depths

Availability of nutrients to a deep-sea benthic microbial community : results from a ship-board experiment

Intact sediment cores from the Vøring-Plateau (Norwegian Sea) were incubated under in situ temperature on board ship with and without the addition of natural detritus to follow the reaction of deep-sea benthic microbial communities to nutrient enrichment. Concentration and enzymatic decomposition of organic material, total microbial number, biomass and production were followed in timecourse experiments. The addition of decomposable organic material caused an immediate stimulation of microbial metabolic processes: following the induction of enzymatic activity, microbial biomass production increased. During the initial period of incubation metabolic processes were also stimulated in the untreated "control" sediments. This "incubation effect" competed with the "feeding effect" caused by the enrichment with organic material

PCR detection and 16S rRNA sequence-based phylogeny of a novel Propionibacterium acidipropionici applicable for enhanced fermentation of high moisture corn

AIMS The aims of this study were to develop a sensitive and more rapid detection of Propionibacterium acidipropionici DH42 in silage and rumen fluid samples, and to explore its 16S rRNA sequence-based phylogeny. METHODS AND RESULTS Nested polymerase chain reaction (PCR) was used with DH42-specific primers dhb1 and dhb2 for the secondary amplification of a 1267-bp fragment of 16S rRNA encoding gene. Using the established protocols for PCR amplification, as low as 10(2) and 10(3) CFU ml(-1) of strain DH42 in silage extracts and rumen fluid, respectively, were detected. To determine phylogenetic relationships between DH42 and other representatives of Propionibacterineae, a 1529-bp fragment of its 16S rRNA was amplified by PCR and sequenced. The propionibacterium DH42 formed a cluster with Eubacterium combesii, P. acidipropionici and P. microaerophilus. CONCLUSIONS 16S rRNA-based PCR detection technique was developed for DH42 in silage and rumen fluid samples. The 16S rRNA sequence confirmed the earlier identification of strain DH42 as P. acidipropionici. However, variable nucleotide positions were revealed. SIGNIFICANCE AND IMPACT OF THE STUDY Variability of 16S rRNA sequence within the species P. acidipropionici, determined in this study, poses the need of re-sequencing for some species of the suborder Propionibacterineae for a more reliable classification