Shewanella irciniae sp nov., a novel member of the family Shewanellaceae, isolated from the marine sponge Ircinia dendroides in the Bay of Villefranche, Mediterranean Sea

Strain UST040317-058(T), comprising non-pigmented, rod-shaped, facultatively anaerobic, Gram-negative cells that are motile by means of single polar flagella, was isolated from the surface of a marine sponge (Ircinia dendroides) collected from the Mediterranean Sea. Comparative 16S rRNA gene sequence-based phylogenetic analysis placed the strain in a separate cluster with the recognized bacterium Shewanella algae IAM 14159(T), with which it showed a sequence similarity of 95.0 %. The sequence similarity between strain UST040317-058(T) and its other (six) closest relatives ranged from 91.6 to 93.8 %. Strain UST040317-058(T) showed oxidase, catalase and gelatinase activities. The typical respiratory quinones for shewanellas, menaquinone MK-7 and ubiquinones Q-7 and Q-8, were also detected. The predominant fatty acids in strain UST040317-058(T) were i15 : 0, 16 : 0, 17 : 1omega8c and summed feature 3 (comprising i15 : 0 2-OH and/or 16 : 1omega7c), altogether representing 56.9 % of the total. The DNA G+C content was 39.9 mol%. The strain could be differentiated from other Shewanella species by its inability to reduce nitrate or produce H(2)S and by 10-22 additional phenotypic characteristics. On the basis of the phylogenetic and phenotypic data presented in this study, strain UST040317-058(T) represents a novel species in the genus Shewanella, for which the name Shewanella irciniae sp. nov. is proposed. The type strain is UST040317-058(T) (=JCM 13528(T)=NRRL B-41466(T))

Quorum Sensing Influences Vibrio harveyi Growth Rates in a Manner Not Fully Accounted For by the Marker Effect of Bioluminescence

The light-emitting Vibrios provide excellent material for studying the interaction of cellular communication with growth rate because bioluminescence is a convenient marker for quorum sensing. However, the use of bioluminescence as a marker is complicated because bioluminescence itself may affect growth rate, e.g. by diverting energy. quorum mutants. growth rate can be either positive or negative and includes both bioluminescence-dependent and independent components. Bioluminescence tends to slow growth rate but not enough to account for the effects of quorum sensing on growth rate

Behavioral and Chemical Ecology of Marine Organisms with Respect to Tetrodotoxin

The behavioral and chemical ecology of marine organisms that possess tetrodotoxin (TTX) has not been comprehensively reviewed in one work to date. The evidence for TTX as an antipredator defense, as venom, as a sex pheromone, and as an attractant for TTX-sequestering organisms is discussed. Little is known about the adaptive value of TTX in microbial producers; thus, I focus on what is known about metazoans that are purported to accumulate TTX through diet or symbioses. Much of what has been proposed is inferred based on the anatomical distribution of TTX. Direct empirical tests of these hypotheses are absent in most cases

Larval pufferfish protected by maternal tetrodotoxin

Marine pufferfish contain tetrodotoxin (TTX), an extremely potent neurotoxin. All species of the genus Takifugu accumulate TTX in the liver and ovaries, although the tissue(s) in which it is localized can differ among species. TTX is the major defense strategy the pufferfish appears to use against predators. TTX is also used as a male-attracting pheromone during spawning. Here we demonstrate an additional (and unexpected) use of maternal TTX in the early larval stages of the Takifugu pufferfish. Predation experiments demonstrated that juveniles of all the species of fish used as predators ingested pufferfish larvae, but spat them out promptly. Liquid Chromatography-Tandem Mass Spectrometry (LC-MSMS) analysis revealed that the pufferfish larvae contain a small quantity of TTX, which is not enough to be lethal to the predators. Immunohistochemical analysis with anti-TTX monoclonal antibody revealed that the TTX is primarily localized in the body surface of the larvae as a layer of protection. Our study showed the female parent of the Takifugu pufferfish vertically transfers TTX to the larvae through its accumulation in the ovaries, and subsequent localization on the body surface of the larvae

The gut microbiota of marine fish

The body of work relating to the gut microbiota of fish is dwarfed by that on humans and mammals. However, it is a field that has had historical interest and has grown significantly along with the expansion of the aquaculture industry and developments in microbiome research. Research is now moving quickly in this field. Much recent focus has been on nutritional manipulation and modification of the gut microbiota to meet the needs of fish farming, while trying to maintain host health and welfare. However, the diversity amongst fish means that baseline data from wild fish and a clear understanding of the role that specific gut microbiota play is still lacking. We review here the factors shaping marine fish gut microbiota and highlight gaps in the research

South Pacific Ocean

航海番号: KH-88-1 ; 航海日程: January 22 - March 25, 198

Heterotrophic bacterial flora of the Antarctic Ocean

Vertical distribution of heterotrophic bacteria was surveyed at six sampling stations in the Antarctic and the Indian Oceans. Seawater samples were collected at various water depths, ranging from 0 to 2000m. Total bacterial counts were determined by the direct microscopic method. Plate counts were carried out by the surface spreading method and the filter method using ORI agar medium. At a sampling station in the Antarctic Ocean, the enumeration of oligotrophic bacteria was also made using an MPN method. The total bacterial counts per ml of seawater in the Antarctic region ranged from (10)^4 to (10)^5,whereas the plate counts by the filter method were (10)^0 to (10)^1 at the upper 500m layers and (10)^ to (10)^0 at the deeper water lyers. The plate counts at 2℃ incubation temperature were higher than those at 20℃ by 1-2 orders of magnitude for the samples at stations in the Antarctic region. In contrast, the 20℃ counts for seawater from the Indian Ocean were slightly higher than 2℃ counts. The surface spreading method gave bacterial counts that were one order of magnitude higher than the filter method, and the counts with the MPN method using diluted medium were greater still, reaching about 10% of total bacterial counts. The results suggested that a fairly large proportion of the bacterial population in Antarctic seawater is in the actively growing state. More than 87% of the bacterial strains isolated from surface water of the Antarctic Ocean were orange- and yellow-pigmented bacteria. Among the pigmented bacteria, Gram-negative, non-motile, orange-pigmented rods that appeared to constitute a single species belonging to Flavobacterium-Cytophaga predominated