Comprehensive understanding of biological wastewater treatment mechanisms was prevented because a wide range of uncultured and unknown lineages existed in the wastewater treatment sludges. In this study, therefore, to understand the patterns of uncultured phyla in wastewater treatment sludges, we analyzed a total of 54 aerobic, anoxic and anaerobic sludge samples collected from 17 different wastewater treatment reactors by massively parallel 16S rRNA gene sequencing. We analyzed total of 1, 041, 539 sequence reads of 16S rRNA gene. The results of microbial community analysis at the phylum level and phylogenetic diversity analyses indicated that patters of microbial communities depended heavily on types of wastewater and types of treatment technologies. We could estimate the putative habitats and environmental conditions of these uncultured lineages by the distribution pattern of the microbial communities in different wastewater treatment sludges.

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 The Japanese deep sea waters contain several recently discovered energy and mineral resources, such as methane hydrate and hydrothermal vents. This study examined the feasibility of in-situ ground improvement technologies for promoting precipitation of minerals based on in-situ microbial functions. The study also examined the solidification effect of deep-sea surface sediments. We sampled seawater from sea surface level to a depth of 750 m in the Toyama Bay using an oceanographic ship and carried out two types of calcium carbonate precipitation tests. The main findings of this research are as follows: (1) the population of urease-producing bacteria from sea surface to deep sea waters can enhance the 1-month cultivation and (2) these bacteria can accelerate the calcite precipitation.

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 Hydroxypropylcellulose (HPC) powder was selected as polymer gel material, and the HPC hydrogel was prepared applying the radiation crosslinking technique. The hydrogel was packed into a carbon felt hollow cylinder (carrier), and then the carrier was submerged in the reactor. After a 2-week bacterial acclimatization period, the continuous denitrification experiments were carried out over three months. In the experiment using the carrier without the hydrogel, total nitrogen (TN) concentration in the reactor was not decreased. On the other hand, a significant difference between influent and effluent TN concentrations was recognized in the experiment using the carrier with the hydrogel. The use of the hydrogel stimulated the denitrification in the reactor. These results showed that the hydrogel could be used as an electron donor and/or carbon source in the denitrification.

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