Outer membrane proteins (OMP) of the marine fish pathogen, Vibrio (Listonella) anguillarum, were examined in a wild type strain and an oxytetracycline (OTC) resistant strain. When the OTC resistant strain was cultured in the presence of OTC, the concentration of a major porin, Omp35La, decreased whereas the concentration of an unknown 26kDa OMP increased. The latter OMP was designated Omp26La. The change in the expression of Omp35La and Omp26La was unaffected by treatment with tetracycline, chlorotetracycline, maltose, rafinose and glucose. Additionally, heat shock treatment did not affect the OMP profiles. Although whether the regulation of both OMPs correlates or not is unclear, it is suggested that OTC specifically affected the expression of both OMPs in the OTC resistant strain. The nucleotide and deduced amino acid sequences of Omp26La were similar to the known OMP (OmpV) of Vibrio cholarae. From the amino acid composition and hydropathy profile, Omp26La was found to have a similar structure to porins such as OmpC and OmpF of E. coll.
Mangrove forests covered almost the costal areas in tropical and subtropical countires on the earth. Mangroves have been used for centuries by peoples overthere as a source for fuel, food, housing, and an endless variety of items. Recent years significant decrease in the area of mangrove forests became one of the serious issues for the global ecology. A little of knowlege is available about the basical ecological research of mangloves and mangrove ecosystems. In this topics microbial ecology in mangrove was summarized in the viewpoints of microbial flora, their biomass, and the role of microbial communites.
20 years have passed since Woese and Fox proposed the third group of life Archaebacteria in 1977. The presence of the distinct group of Archaebacteria is widely accepted. Although, the principal division of all the living organism has been still a matter of argument. From the analysis of the characteristics of Archaebacteria and from the comparison of that with those of Eukaryotes and Eubacteria, we can speculate the early history of life. The characteristics of a general common ancestor (Commonote) from which all the living organisms have been derived, can be speculated based on the general phylogenetic tree. The general common ancestor has been proposed to be a thermophilic or ultra-thermophilic organism. Although, several other investigators have proposed alternative possibility. Very recently, Doolittle and his coworkers have presented the estimation of the time of major division of life in the history. It may be also possible to get information related to the process evolving the first cell of Eukaryotes from the analysis of Archaebacteria.
In the last two decades, many hyperthermophiles with optimum growth temperatures above 80°C have been isolated from natural high temperature ecosystems. In this overview, we summarize the geological setting and chemistry of marine hydrothermal environments and the features of several representative marine hyperthermophilic isolates.
Importance of autotrophs is described from the standpoint of global material circulation and carbon dioxide fixing ability. Carbon dioxide fixation pathways and electron transport systems in hyperthermophiles are described in detail. Also, brief listings of hyperthermophiles with ability to grow chemoautotrophically are performed.
Thermophilic prokaryotes may be the oldest organisms to have been living in thermal environments since the early ecosystem on the Earth dating back to 3.8 billion years ago. Probably, some kind of hot spring-microbial mats creating by these thermophiles could be regarded as “living fossil”.
Green filamentous bacteria (Chloroflexus) and cyanobacteria are commonly observed in bacterial mats of hot springs with the temperature range betwen 45 and 70°C and pH range between 6.5 and 9.0. Sulfide concentration is another factor which largely affects the distribution of thermophilic photosynthetic bacteria. Chloroflexus spp. are thought to maintain many characteristics of the oldest photosynthetic bacteria. Photosynthetic bacterial mats in hot springs are important for the studies on early stages of the evolution of photosynthesis.