Effects of astaxanthin-rich dried cell powder from Paracoccus carotinifaciens on carotenoid composition and lipid peroxidation in skeletal muscle of broiler chickens under thermo-neutral or realistic high temperature conditions.

Thirty-two 15-day old broiler chicks (Chunky strain ROSS 308) were randomly divided into four treatments in a 2 × 2 factorial design. The main factors were diet (basal diet or basal diet supplemented with 0.15% astaxanthin-rich dried cell powder (Panaferd-P [astaxanthin 30 ppm]) and ambient temperature (thermo-neutral [25 ± 1°C] or high [35 ± 1°C for 6 hr]). Dietary supplementation with Panaferd-P did not affect growth performance, though high ambient temperature decreased feed intake and the weight of breast tender muscle, liver, and heart. High ambient temperature also decreased redness in both breast and leg muscles of chickens, while Panaferd-P increased redness and yellowness of breast and leg muscles of chickens. Panaferd-P increased Paracoccus carotinifaciens-derived pigments (i.e., adonixanthin, astaxanthin, adonirubin, and cantaxanthin) as well as corn-derived pigments such as zeaxanthin and lutein in breast and leg muscles. High ambient temperature increased the malondialdehyde (MDA) concentration in breast muscle, while Panaferd-P decreased the MDA concentration in breast muscle under both temperature conditions. Our results suggest that dietary supplementation with Panaferd-P increases muscle carotenoid content, the redness and yellowness of meat and decreases the muscle MDA concentration in broiler chickens kept under thermo-neutral or high ambient temperature conditions.

Influence of DMF-induced oxidative stress on membrane and periplasmic proteins in Paracoccus sp. SKG.

The present study describes the N,N-dimethylformamide (DMF)-induced oxidative stress in Paracoccus sp. SKG. The oxidative stress was evaluated by analysing membrane and periplasmic proteins and K+ efflux, as well as by monitoring the activities of antioxidant enzymes like catalase, superoxide dismutase (SOD) and glutathione S-transferase (GST). The exposure of bacterial cells to a higher concentration of DMF resulted in the modification of membrane fatty acid composition which is accompanied by K+ efflux. Further, this oxidative stress resulted in increased periplasmic protein which can be attributed to the induction of GST and methionine sulphoxide reductase (Msr) enzymes under solvent stress. Paracoccus sp. SKG is tolerant to high concentrations of DMF up to 6% (v/v) and its toxic effects. DMF concentration-dependent induction of GST and Msr activities advocates the significant role of these enzymes in the bacterial defence system. The present study provides information which helps us to understand the ROS scavenging machinery in bacteria. The high tolerance of Paracoccus sp. SKG to DMF can be efficiently explored for various bioremediation and biotransformation applications.

Paracoccus sulfuroxidans sp. nov., a sulfur oxidizer from activated sludge.

Bacterial strain LW36T was isolated from activated sludge of a wastewater-treatment bioreactor. Cells of strain LW36T were Gram-negative coccoids to short rods, 1.0-1.2x0.5 microm in size. Colonies were cream-coloured, smooth and circular. Strain LW36T was hetero-organotrophic and chemolithotrophic and was able to use reduced sulfur as an energy resource. Growth was observed at 25-36 degrees C and pH 5-10. The most abundant cellular fatty acid of strain LW36T was C18:1omega7c (64.2%). The sole respiratory quinone was ubiquinone-10. The G+C content of the genomic DNA was 61.3 mol% (Tm). 16S rRNA gene sequence analysis indicated that strain LW36T was phylogenetically related to members of the genus Paracoccus, with similarities ranging from 92.4 to 94.9%. Based on these results, it is concluded that strain LW36T represents a novel species of the genus Paracoccus, for which the name Paracoccus sulfuroxidans is proposed. The type strain is strain LW36T (=CGMCC 1.5364T=JCM 14013T).

[Methanotrophs and methylobacteria are found in woody plant tissues within a winter period]. / Metanotrofy i metilobakterii obnaruzheny v tkaniakh drevesnykh rastenii v zimnii period.

Samples of tree seeds, buds, and needles collected within a winter period at ambient temperatures from -11 to -17 degrees C were analyzed for the presence of methylotrophic microflora. Thin sections of blue spruce needles were found to contain bacteria morphologically close to pink-pigmented methylobacteria. The methylobacteria that were isolated in pure cultures from samples of linden seeds and buds, pine and blue spruce needles, as well as of lilac, maple, and apple buds, were classified into the genera Methylobacterium and Paracoccus based on the data of morphological studies, enzyme assay, and DNA-DNA hybridization analysis. The methanotrophs that were isolated in pure cultures from samples of linden buds and blue spruce needles were identified into the genus Methylocystis based on the data of morphological studies, enzyme assay, DNA-DNA hybridization, and the phylogenetic analysis of the particulate methane monooxygenase gene pmoA sequences. The inference is made that aerobic methylotrophic bacteria are permanently associated with plants. At the beginning of the vegetative period in spring, the phyllosphere of coniferous and deciduous trees is colonized by the methylotrophic bacteria that have wintered inside plant tissues.