Caulobacter zeae sp. nov. and Caulobacter radicis sp. nov., novel endophytic bacteria isolated from maize root (Zea mays L.).

Four bacterial strains designated 410T, 441, 695T and 736 were isolated from maize root in Beijing, P. R. China. Based on 16S rRNA gene phylogeny, the four strains formed two clusters in the genus Caulobacter. Since strain 441 was a clonal variety of strain 410T, only three strains were selected for further taxonomic studies. The whole genome average nucleotide identity (ANI) value between strains 410T and 695T was 94.65%, and both strains shared less than 92.10% ANI values with their close phylogenetic neighbors Caulobacter vibrioides DSM 9893T, Caulobacter segnis ATCC 21756T and Caulobacter flavus CGMCC 1.15093T. Strains 410T and 695T contained Q-10 as the sole ubiquinone and their major fatty acids were C16:0, 11-methyl C18:1ω 0, 11-methyl C18: 1ω7c, summed feature 3 (C16:1ω7c and/or C16:1ω 1ω7c and/or C16: 1ω6c) and summed feature 8 (C18:1ω7c and/or C18:1ω 1ω7c and/or C18: 1ω6c). Their major polar lipids consisted of glycolipids and phosphatidylglycerol, and phenotypic tests differentiated them from their closest phylogenetic neighbors. Based on the results obtained, it is proposed that the three strains represent two novel species, for which the names Caulobacter zeae sp. nov. (type strain 410T=CGMCC 1.15991=DSM 104304) and Caulobacter radicis sp. nov. (type strain 695T=CGMCC 1.16556=DSM 106792) are proposed.

[Ammonia Removal Rate and Microbial Community Structures in Different Biofilters for Treating Aquaculture Wastewater].

Three MBBRs and three curtain type trickling filters (CTFs) with different carriers were operated in lab-scale simulated RASs. The characteristics of biofilms, ammonia removal rates and microbial communities in six reactors were compared with each other. Compared with the biofilms of MBBRs, the biofilms of CTFs were heavier and grew faster. The weight of biofilms on CTFs with carbon fiber carriers was the maximum (45.97 g·m-2), and the ammonia nitrogen removal efficiency (86.76%) of this CTFs was higher than the other filters or reactors (61.96%~78.76%). In addition, the concentration of the accumulated nitrite in the carbon fiber CTFs was the lowest in all the six reactors. The microbial communities of biofilms in the six biofilters were evaluated by the high-throughput Illumina-MiSeq sequencing technology. The results showed that the microbial (bacteria and eukaryote) community in biofilms of CTFs was different from that in biofilms of MBBRs. At both bacteria and micro-eukaryote level, the species richness and biological diversity of biofilms in the trickling filters were higher than those in the MBBRs. On the contrary, the Simpson index of bacterial community in biofilms of MBBRs was higher than that in the trickling filters. In all the six biofilters, Nitrospira and Nakamurella were the dominated bacterial genera. Saprospiraceae was more abundant in CTFs than in MBBRs, but Comamonadaceae was enriched in the MBBRs. At the micro-eukaryote genus level, Rhabditida norank genus was more abundant in CTFs, while Chlorophyceae norank genus was more abundant in the MBBRs. The results provide useful information about microbial ecology that can be used for the application of CTFs in RAS.

[Concentration and size distribution of bioaerosols at non-haze and haze days in Beijing].

In recent years, haze has been observed frequently in Beijing. Haze was one of the atmospheric phenomena caused by the accumulation of particulate matter. As an important fraction of particular matter, bioaerosol could potentially cause significantly negative health effects. In this study, we detected the concentration and size distribution of viable bioaerosol during non-haze and haze days, analyzed correlation of viable bioaerosol with the ambient temperature and relative humidity using Spearman's correlation coefficient and finally detected the changing of size distribution of viable bioaerosol in summer and winter. Results indicated that concentrations of viable bioaerosol exhibited a negative correlation with Air Quality Index (AQI) of PM2.5 and positive correlation with temperature. Relative humidity had a negative correlation with airborne bacteria while positive correlation with airborne fungi. The highest concentration of airborne bacteria and fungi were detected at size arrange of 4.5-7.0 µm and 2. 1-3.3 µm in the winter, respectively. In the summer, both the highest concentration of airborne bacteria and fungi were observed at size arrange of 3.3-4.5 µm. The results of this study will provide the basis data for hazard evaluation of bioaerosol on human health at non-haze and haze days.

[Analysis on microbial community in biofilm coating onto solid carbon source using the PCR-DGGE technique].

Polylactic acid/Poly (3-Hydroxybutyrate-co-3-Hydroxyvalerate) (PLA/PHBV) granules were used as both carbon source and biofilm carrier for nitrate removal from the contaminated water. The polymerase chain reaction-denature gradient gel electrophoresis (PCR-DGGE) was used to investigate the dynamic change of microbial community in the biofilm coating onto PLA/PHBV granules. The results showed that a decrease in microbial diversity was observed at the initial stage of reactor operation. Shannon-Wiener and Simpson diversity indexes of microbial community in the biofilm slightly changed during the stable period of the reactor running. The major microorganisms in the biofilm were Gram-negative rod bacteria including the genera of Diaphorobacter, Acidovorax, Rubrivivax, Azospira, Thermomonas and Devosia, and all of them belonged to alpha-, beta- and gamma- Proteobacteria, according to the SEM photo of biofilm and 16S rDNA sequences of the DGGE profile. Moreover, the abundance of Diaphorobacter-like genera was the highest in the solid-phase-denitrification biofilm.