Respiration-dependent primary Na+ pump in halophilic marine bacterium, Alcaligenes strain 201

AbstractThe inverted membrane vesicles of marine bacterium Alcaligenes strain 201 generated inside positive membrane potential and accumulated Na+ on the energization with NADH. Both the generation of membrane potential and the accumulation of Na+ were resistant to a proton conductor, carbonyl cyanide m-chlorophenylhydrazone. Collapse of the membrane potential by valinomycin resulted in the stimulation of Na+ accumulation. It was concluded that Alcaligenes strain 201 possesses a respiratory Na+ pump which is analogous to that of Vibrio alginolyticus.Inverted vesicle; Na+ pump; Marine bacteria; Respiratory chai

Alkane-degrading bacteria and heavy metals from the Nakhodka oil spill-polluted seashores in the Sea of Japan after five years of bioremediation

Graduate School of Natural Science and Technology, Kanazawa UniversityDepartment of Earth Sciences, Faculty of Science, Kanazawa UniversityDepartment of Earth Sciences, Faculty of Science, Kanazawa UniversityOcean Research Institute, University of TokyoThis paper describes the isolation of alkane-degrading bacteria from the Nakhodka oil spill-polluted seashores in the Sea of Japan. Seven representative strains were identified using 16S rDNA sequence analysis as Bacillus spp., Pseudomonas sp., and Paracoccus spp. All bacterial strains showed their ability to grow well on aliphatic hydrocarbons, but not on aromatic hydrocarbons. In addition, elemental levels in heavy oil showed wide ranges in all the heavy oil samples consisting of Si, S, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb. Compounds of Si, S, and Cr were observed at high levels, while those of Ti, Mn, Fe, Co, Ni, Cu, Zn, and Pb were observed at low levels. Of all heavy metals, Co appeared to be toxic for all bacterial growth at concentrations of >1 ppm, while the presence of Ti, Cr, and Cu at 0.01 to 10 ppm were found not to inhibit growth of all bacterial strains. It is suspected that the presence of heavy metals may have a significant effect on the composition of the bacterial community, (i.e., alkane-degrading bacterial isolates), as well as on the biodegradative processes of the Nakhodka oil spill during the 5-year bioremediation

Immunoglobulin G4-Related Hepatic Inflammatory Pseudotumor Diagnosed with Endoscopic Ultrasound-Guided Fine-Needle Biopsy

A 71-year-old man with obstructive jaundice was referred to our department. He underwent cholangiojejunostomy 15 years ago for palliative drainage. At that time, he had obstructive jaundice caused by an unresectable pancreatic head tumor. Contrast-enhanced computed tomography (CE-CT) now revealed a mass with low enhancement in the hepatic hilum that occluded the hilar bile duct and infiltrated extensively along the portal vein and hepatic artery. CE-CT also showed marked atrophy of the left hepatic lobe. No swelling or tumors were observed in the pancreas. Serum immunoglobulin G4 (IgG4) levels were as high as 465 mg/dL. Endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) was performed targeting the hepatic hilar lesion. Immunohistological results of the biopsy specimens suggested that the lesion was an IgG4-related hepatic inflammatory pseudotumor (IPT) with no atypical cells. Steroid treatment resulted in rapid clinical improvement. This case suggested the usefulness of EUS-FNB for diagnosing IgG4-related hepatic hilar IPT

Presence of genes for type III secretion system 2 in Vibrio mimicus strains

<p>Abstract</p> <p>Background</p> <p>Vibrios, which include more than 100 species, are ubiquitous in marine and estuarine environments, and several of them e.g. <it>Vibrio cholerae</it>, <it>V. parahaemolyticus</it>, <it>V. vulnificus </it>and <it>V. mimicus</it>, are pathogens for humans. Pathogenic <it>V. parahaemolyticus </it>strains possess two sets of genes for type III secretion system (T3SS), T3SS1 and T3SS2. The latter are critical for virulence of the organism and be classified into two distinct phylogroups, T3SS2α and T3SS2β, which are reportedly also found in pathogenic <it>V. cholerae </it>non-O1/non-O139 serogroup strains. However, whether T3SS2-related genes are present in other <it>Vibrio </it>species remains unclear.</p> <p>Results</p> <p>We therefore examined the distribution of the genes for T3SS2 in vibrios other than <it>V. parahaemolyticus </it>by using a PCR assay targeting both T3SS2α and T3SS2β genes. Among the 32 <it>Vibrio </it>species tested in our study, several T3SS2-related genes were detected in three species, <it>V. cholerae</it>, <it>V. mimicus </it>and <it>V. hollisae</it>, and most of the essential genes for type III secretion were present in T3SS2-positive <it>V. cholerae </it>and <it>V. mimicus </it>strains. Moreover, both <it>V. mimicus </it>strains possessing T3SS2α and T3SS2β were identified. The gene organization of the T3SS2 gene clusters in <it>V. mimicus </it>strains was fundamentally similar to that of <it>V. parahaemolyticus </it>and <it>V. cholerae </it>in both T3SS2α- and T3SS2β-possessing strains.</p> <p>Conclusions</p> <p>This study is the first reported evidence of the presence of T3SS2 gene clusters in <it>V. mimicus </it>strains. This finding thus provides a new insight into the pathogenicity of the <it>V. mimicus </it>species.</p

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

Abundance and production of bacterioplankton in the Antarctic

The abundance and production rate of bacterioplankton in the Antarctic were measured in order to clarify their role in the food web. The production rate was estimated from the incorporation rate of [methyl-^3H] thymidine into TCA (trichloroacetic acid) insoluble fraction. In summer, the production in the upper layer ranged 0.45-5.2×(10)^7 cells/l/day, which correspond to e. g., 0.068-0.79μgC/l/day. The apparent doubling time of bacterial population was an order of a few days, which was equal to that observed in an equatorial area. Both abundance and production rate decreased with depth. The isotope dilution method to clarify the size of intracellular dTTP (deoxythymidine triphosphate) pool did not give meaningful data. The present results indicate that the abundance and production rate of bacterioplankton in the Antarctic were as high as those in an equatorial or temperate zone

The role of epiphytic and epibenthic algal productivity in a tropical seagrass, Syringodium isoetifolium (Aschers.) Dandy, community

The overall aim of this study, which was part of a multidisciplinary investigation, was to evaluate the role of epiphytic and epibenthic algae in a tropical seagrass, Syringodium isoetifolium (Aschers.) Dandy, community. Algal biomass (chlorophyll a) and productivity were determined over 20 days. The rates of photosynthesis were measured with both gas (oxygen) release and HCO incorporation techniques. The photosynthetic characteristics of the algal community are described by the relationship between the rates of photosynthesis and irradiance (PI curve). The saturating light intensity (I), determined in the laboratory, was 240 µE m s (1 µE = 1 µmol). However, the maximum rate of net epibenthic production (P) in situ of 2 g C g chla h was reached only at light intensities above the leaf canopy of more than 480 µE m s because of shading.The photoperiod (the period when algae were at P) was determined from the daily light profiles and used to calculate the mean net productivity of the epibenthic (4-2 g C m day) and epiphytic (11-5 gCm day) algae during the study. The net epiphytic and seagrass productivities were equal and positively correlated (slope = 1.0; r = 0.92). However, the net seagrass leaf production was only 25% of the total seagrass net production. Most of the seagrass production appeared to be directed elsewhere, possibly into the below-ground tissue. Epiphytic algae accounted for more than four times the above-ground primary production. Compared with the bare sediment surface, the dense seagrass stand afforded 27 ±4 (s.d.) times more surface area on which the epiphyton could colonize. Thus, seagrasses provided the surfaces essential for maintaining the substantial epiphytic primary productivity, a passive but nonetheless important role. We compare our findings with other results of the multidisciplinary study and construct a carbon budget from which we infer a model of carbon transfer through this ecosystem. The algae were quantitatively the most important of the primary producers, seeming to provide most of the organic carbon to the higher trophic groups, at least for the period of this study

Bacterial decomposition of detritus in a tropical seagrass (Syringodium isoetifolium) ecosystem, measured with [methyl-3H]thymidine

The bacterial decomposition of detritus was measured in a tropical seagrass meadow (Syringodium isoetifolium) off Dravuni Island, Fiji, and compared with the seagrass and algal productivity. Our estimates of bacterial decomposition of organic matter was based on the rate at which the bacteria divided, and this was measured by the rate at which [methyl-3H]thymidine was incorporated into the bacterial DNA. Bacterial activity was greatest in the top 1 cm of the seagrass sediments. The number of bacteria, their specific growth rate, and their productivity were 6.3±0.3×10 cells cm, 0-04 ± 0-005 h, and 0.671 g C day m (depth-integrated over 30 cm), respectively. At the sediment surface, bacterial activity coincided with the daily light intensities during the day. Benthic microalgal production seemd to be coupled to the heterotrophic bacterial activity. However, the amount of organic carbon passing through the bacterial decomposition process was small compared with the total autotrophic production. The net bacterial productivity was only between 4 and 6% of that of microalgae and 6% of that of the seagrass. The bacteria appeared to play a minor role in the transfer of organic carbon between the primary producers and the higher trophic groups. Much of the microalgal production could have been directly consumed by the benthic infauna, whereas the seagrass production may have been translocated, via the seagrass roots and rhizomes, to other parts of the plant and/or converted into more refractory or storage compounds