Recently it was shown that motility of Vibrio alginolyticus facilitated cell attachment to glass surfaces. In the present study the same relationship between motility and cell attachment was confirmed for Alcaligenes and Alteromonas spp. These findings clearly answer a long-standing question : does motility facilitate attachment ? However, they are contradictory to a general view on cell attachment that the energy barrier due to electrostatic repulsion between negatively charged bacterial cells and a glass surface is much greater than both the thermal kinetic energy of the bacterial cell and the bacterial swimming energy. It is shown that the energy barrier becomes far less than that usually estimated when bacterial cells are rich in polymers at their surfaces. This finding reasonably explains the dependence of bacterial attachment rate on cell motility and demands reconsideration of the mechanism of bacterial attachment.

Benthic foraminiferal food sources were examined in the central part of Sagami Bay, Japan (water depth 1450 m) based on an in situ feeding experiment with 13 C-labeled food materials. In this study, 3 different 13 C-labeled food materials were used: the unicellular marine algae Dunaliella tertiolecta, the marine diatom Chaetoceros sociale, and the marine bacterium Vibrio alginolyticus. The first two are representatives of phytodetritus and the third of organic matter produced in the sediments. Each type of food material was injected into a series of in situ culture cores and incubated for up to 21 d. We observed that some benthic foraminiferal species selectively ingested 13 C-labeled algae from the sedimentary organic matter. On the other hand, benthic foraminifera ingested 13 C-labeled bacteria unselectively from sedimentary organic matter. Total benthic foraminifera assimilated 8.8 mg C m-2 d-1 of sedimentary organic matter without phytodetritus assimilation. Based on the assimilation rates estimated in this experiment, we recognized 3 types of feeding strategy among deep-sea benthic foraminifera in Sagami Bay. There are those that ingest (1) fresh phytodetritus selectively (phytophagous species: Uvigerina akitaensis, Bolivina spissa, Bolivina pacifica); (2) fresh phytodetritus selectively but sedimentary organic matter as well when phytodetritus is absent (seasonal-phytophagous species: Bulimina aculeata, Textularia kattegatensis, Globobulimina affinis); and (3) sedimentary organic matter at random (deposit feeders: Cyclammina cancellata, Chilostomella ovoidea). These different types of carbon utilization should be considered not only for understanding modern ecosystems on the deep-sea floor but also for paleoceanographic reconstructions using the abundance and distribution, or isotopic composition, of benthic foraminifera.

Two luminous marine bacterial strains, LC2-005 T and LC2-102, were isolated from seawater at Kuroshio Region and Sagami Bay in Japan, respectively. These bacteria were Gram-negative, oxidase-positive, catalase-positive, motile and rod-shaped. On the basis of 16S rRNA gene sequence analysis, strains LC2-005 T and LC2-102 formed a cluster within the Vibrio harveyi species group. However, multilocus sequence analysis using five loci (pyrH, ftsZ, mreB, gyrB and gapA) and DNA-DNA hybridization experiments indicated that these strains were distinct from the currently known Vibrio species. Additionally, these strains differ from related Vibrio species in utilization of glucose, mannitol, inositol, sorbitol, rhamnose, sucrose, melibiose and arabinose, production of lysine decarboxylase, ornithine decarboxylase, tryptophan deaminase, esterase (C4), lipase (C4), chymotrypsin, acid phosphatase, a-glucosidase, b-glucosidase and N-acetyl-bglucosaminidase and the ability to reduce nitrate to nitrite. The major fatty acids were C 15 : 0 iso 2-OH and/or C 16 : 1 v7c, C 16 : 0 , C 18 : 1 v7c and C 14 : 0 . The DNA G+C contents of strains LC2-005 T and LC2-102 were 45.2 and 45.5 mol%, respectively. On the basis of the polyphasic taxonomic evidence presented in this study, it can be concluded that strains LC2-005 T and LC2-102 belong to the same genospecies and represent a novel species of the genus Vibrio, for which the name Vibrio azureus sp. nov. is proposed. The type strain is LC2-005 T (5NBRC 104587 T 5KCTC 22352 T ).

No abstract

The attachment of Vibrio alginolyticus to glass surfaces was investigated with special reference to the swimming speed due to the polar flagellum. This bacterium has two types of flagella, i.e., one polar flagellum and numerous lateral flagella. The mutant YM4, which possesses only the polar flagellum, showed much faster attachment than the mutant YM18, which does not possess flagella, indicating that the polar flagellum plays an important role. The attachment of YM4 was dependent on Na+ concentration and was specifically inhibited by amiloride, an inhibitor of polar flagellum rotation. These results are quite similar to those for swimming speed obtained under the same conditions. Observations with other mutants showed that chemotaxis is not critical and that the flagellum does not act as an appendage for attachment. From these results, it is concluded that the attachment of V. alginolyticus to glass surfaces is dependent on swimming speed.