Hideyuki Tamaki

Coal-bed methane is one of the largest unconventional natural gas resources. Although microbial activity may greatly contribute to coal-bed methane formation, it is unclear whether the complex aromatic organic compounds present in coal can be used for methanogenesis. We show that deep subsurface-derived Methermicoccus methanogens can produce methane from more than 30 types of methoxylated aromatic compounds (MACs) as well as from coals containing MACs. In contrast to known methanogenesis pathway

Comparative analysis of bacterial diversity in freshwater sediment collected from a shallow eutrophic lake was performed by using 16S rRNA gene clone library and improved cultivation-based techniques. Our study demonstrated that the use of gellan gum as a gelling reagent instead of agar was more effective at increasing culturability, cultivating a diverse array of novel microbes, and reducing the gaps of the results between molecular and cultivation-based analyses.

Our findings clearly demonstrated that alternative pyrosequencing methods for 16S rRNA genes could drastically affect sequencing output (e.g. number of reads before and after trimming) but have little effect on the outcomes of microbial community analysis. This finding is important for both researchers and sequencing facilities utilizing 16S rRNA gene pyrosequencing for microbial ecological studies.

A novel aerobic, chemoheterotrophic bacterium, strain YO-36(T), isolated from the rhizoplane of an aquatic plant (a reed, Phragmites australis) inhabiting a freshwater lake in Japan, was morphologically, physiologically and phylogenetically characterized. Strain YO-36(T) was Gram-negative and ovoid to rod-shaped, and formed pinkish hard colonies on agar plates. Strain YO-36(T) grew at 20-40 °C with optimum growth at 30-35 °C, whilst no growth was observed at 15 °C or 45 °C. The pH range for grow

Viruses have been detected in the different stages of wastewater treatment plants (WWTPs) at concentrations of 10(8) -10(10) ml(-1) of virus-like particles (VLPs), 10-1000 times higher than in natural aquatic environments, suggesting that WWTPs can be considered as an important reservoir and source of viruses. This study revealed novel diversity and function with the DNA viral communities in the influent, activated sludge, anaerobic digester, and effluent of a domestic WWTP using metagenomics. W

Three novel strains of cold-adapted bacteria, ST-82T, ST-10 and ST-92, were isolated from freshwater sediments. These three isolates were very similar to each other in phenotypic and chemotaxonomic traits, as well as in 16S rDNA sequence. The strains were Gram-negative, elongated filament-like rods that formed bright yellow colonies. They showed neither flexirubin pigments nor gliding motility. The strains were able to hydrolyse casein, gelatin, starch, agar, aesculin, urea, uric acid and tyrosi

Since Robert Koch and colleagues found agar to be an effective gelling agent over a century ago, the pure culture method using agar plates has long been a standard of microbiology. Agar is undoubtedly easy to handle and useful for culture of microorganisms, but recent discovery of the ubiquity of microorganisms that cannot be cultured on agar raises a question: is agar really the best agent? In this study, we investigated the effect of two gelling agents, agar and gellan gum, on colony formation

Duckweeds are small, fast growing, and starch- and protein-rich aquatic plants expected to be a next generation energy crop and an excellent biomaterial for phytoremediation. Despite such an importance, very little is known about duckweed-microbe interactions that would be a key biological factor for efficient industrial utilization of duckweeds. Here we first report the duckweed growth promoting ability of bacterial strains belonging to the phylum <i>Acidobacteria</i>, the members of which are

<i>Lactobacillus gasseri</i> is one of the most likely probiotic candidates among many <i>Lactobacillus</i> species. Although bile salt resistance has been defined as an important criterion for selection of probiotic candidates since it allows probiotic bacteria to survive in the gut, both its capability and its related enzyme, bile salt hydrolase (BSH), in <i>L. gasseri</i> is still largely unknown. Here, we report that the well-known probiotic bacterium <i>L. gasseri</i> JCM1131^T po

The bile resistance of intestinal bacteria is among the key factors responsible for their successful colonization of and survival in the mammalian gastrointestinal tract. In this study, we demonstrated that lactate-producing Atopobiaceae bacteria (<i>Leptogranulimonas caecicola</i> TOC12^T and <i>Granulimonas faecalis</i> OPF53^T) isolated from mouse intestine showed high resistance to mammalian bile extracts, due to significant bile salt hydrolase (BSH) activity. We further

N-Acyl homoserine lactones (AHLs) are signaling molecules used in the quorum sensing (QS) of Gram-negative bacteria. Some bacteria interfere with the QS system using AHL-inactivating enzymes, commonly known as quorum-quenching (QQ) enzymes. We have recently isolated a new QQ bacterium showing high resistance to multiple β-lactam antibiotics, and its QQ enzyme (MacQ) confers β-lactam antibiotic resistance and exhibits QQ activities. This observation suggests the possibility of isolating novel QQ

Plant growth-promoting bacteria (PGPB) can exert beneficial growth effects on their host plants. Little is known about the phylogeny and growth-promoting mechanisms of PGPB associated with aquatic plants, although those of terrestrial PGPB have been well-studied. Here, we report four novel aquatic PGPB strains, MRB1-4 (NITE P-01645-P-01648), for duckweed <i>Lemna minor</i> from our rhizobacterial collection isolated from <i>Lythrum anceps</i>. The number of <i>L. minor</i> fronds during 14 days