Xiaomin Hu

Microbial transformation of ginsenosides Rb1, Rb3 and Rc by Fusarium sacchari

Aims:  This study examined the transformation pathways of ginsenosides G‐Rb1, G‐Rb3, and G‐Rc by the fungus Fusarium sacchari.

Paenibacillus shenyangensis sp. nov., a bioflocculant-producing species isolated from soil under a peach tree.

A Gram-stain-positive, aerobic or facultatively anaerobic, rod-shaped, non-motile, endospore-forming bacterium, strain A9(T), was isolated in 1996 from a soil sample collected under a peach tree in Qingnian Park in Shenyang, PR China, and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain belonged to the genus Paenibacillus, and was most closely related to the type strain of Paenibacillus hunanensis with a 16S rRNA gene sequence similarity of 96.7 % and a DNA-DNA relatedness value of 51.6 %. The major polar lipids of strain A9(T) were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The predominant menaquinone was MK-7 and the major cellular fatty acids were anteiso-C15 : 0, C16 : 0 and iso-C15 : 0. The DNA G+C content was 51.9 mol%. Based on these results, it is concluded that strain A9(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus shenyangensis sp. nov. is proposed, with A9(T) ( = JCM 19307(T) = CGMCC 2040(T)) as the type strain.

Effect of iron ions and electric field on nitrification process in the periodic reversal bio-electrocoagulation system

This study explored the nitrification mechanism of a periodic reversal bio-electrocoagulation system with Fe-C electrodes. The ammonia nitrogen removal was compared in four identical cylindrical sequencing bath reactors. Two of them were reactors with Fe-C electrodes (S1) and C-C electrodes (S2), respectively. The other two were a reactor with iron ions (S3) and a traditional SBR (S4), respectively. The results demonstrated that the effect on enhancing nitrification in S1 was the best among all four SBRs, followed by S3, S2 and S4. Iron ions increased the biomass, and electric field improved the proton transfer and enzyme activity. The dominant bacterial genera in the four SBRs were Hyphomicrobium, Thauera, Nitrobacter, Nitrosomonas, Paracoccus and Hydrogenophaga. The iron ions may increase the levels of Nitrosomonas and Nitrobacter, both of which were the main microbes of the nitrification process. This study provided a significant and meaningful understanding of nitrification in a bio-electrocoagulation system.

Clostridium guangxiense sp. nov. and Clostridium neuense sp. nov., two phylogenetically closely related hydrogen-producing species isolated from lake sediment.

Two novel anaerobic, mesophilic, biohydrogen-producing bacteria, designated strains ZGM211T and G1T, were isolated from lake sediment. 16S rRNA and ATP synthase beta subunit (atpD) gene sequences and phylogenetic analysis of strains ZGM211T and G1T revealed an affiliation to the genus Clostridium sensu stricto (cluster I of the clostridia), with Clostridium acetobutylicum as the closest characterized species, showing the same sequence similarity of 96.4 % to the type strain (98.9 % between the two isolates). Cells of the two strains were rod shaped. Growth occurred at 20-45 °C, pH 4.0-8.0 and NaCl concentrations up to 2 % (w/v). Grown on glucose, the main fermentation products were H2, CO2, acetate and butyrate. The major fatty acids were C14 : 0 and C16 : 0. The DNA G+C contents of strains ZGM211T and G1T were 40.7 and 41.5 mol%, respectively. Based on phenotypic, chemotaxonomic and phylogenetic differences, strains ZGM211T (=CICC 24070T=BCRC 80950T) and G1T (=CICC 24069T=BCRC 80949T) are proposed as the type strains of novel species of the genus Clostridium with the names Clostridium guangxiense sp. nov. and Clostridium neuense sp. nov., respectively.

Influence of electric field and iron on the denitrification process from nitrogen-rich wastewater in a periodic reversal bio-electrocoagulation system

This study proposed a periodic reversal bio-electrocoagulation system (PRBES) with Fe-C electrodes and three other control systems and explored their denitrification mechanism. The experimental results illustrated that iron ions contributed to increasing biomass and denitrifying bacteria and that the electric field may enhance the nitrogen transfer rate and enzyme activities. The dominant bacterial genera in the four systems were the Enterobacter (32.75%), Thauera (9.29%), Paracoccus (8.54%), Hyphomicrobium (5.01%) and Saccharibacteria_genera (10.57%). The sum of the relative abundance of the first four bacteria, which were the major microorganisms in the denitrification process in this study, was 64.61%, 55.40%, 61.19% and 47.08%, respectively, in PRBES and the three other control systems at 10 °C. Additionally, compared to the conventional SBR, there was a 65.48% decrease in N2O in PRBES at 10 °C. This study provided a meaningful and significant understanding of denitrification in PRBES when treating nitrogen-rich wastewater.

Performance and microbial community analysis of bio-electrocoagulation on simultaneous nitrification and denitrification in submerged membrane bioreactor at limited dissolved oxygen

A pair of Fe-C electrodes was installed in a traditional submerged membrane bioreactor (MBR, Rc), and a novel asynchronous periodic reversal bio-electrocoagulation system (Re) was developed. The simultaneous nitrification and denitrification (SND) performance was discussed under limited dissolved oxygen (DO). Results showed that electrocoagulation enhanced total nitrogen (TN) removal from 59.48% to 75.09% at 1.2 mg/L DO. Additionally, Fe electrode could increase sludge concentration, particle size, and enzyme activities related to nitrogen removal. The enzyme activities of Hydroxylamine oxidoreductase (HAO), Nitrate Reductase (NAR), nitric oxide reductase NOR and nitrous oxide reductase (N2OR) in Re were 38.35%, 21.59%, 89.96% and 38.64% higher than Rc, respectively. Moreover, electrocoagulation was advantageous for nitrite accumulation, indicating partial nitrification and denitrification were more easily achieved in Re. Besides, results from high throughput sequencing analysis revealed that electrocoagulation increased the relative abundance of most genera related to nitrogen removal, including Nitrosomonas, Comamonadaceae_unclassified, Haliangium and Denitratisoma.

Draft Genome Sequence of the Efficient Bioflocculant-Producing Bacterium Paenibacillus sp. Strain A9

ABSTRACT Paenibacillus sp. strain A9 is an important bioflocculant-producing bacterium, isolated from a soil sample, and is pale pink-pigmented, aerobic, and Gram-positive. Here, we report the draft genome sequence and the initial findings from a preliminary analysis of strain A9, which is a novel species of Paenibacillus.

Massilia neuiana sp. nov., isolated from wet soil

A novel aerobic, Gram-stain-negative, rod-shaped, motile bacterium, strain PTW21T, was isolated from wet soil. 16S rRNA gene sequence phylogenetic analysis of strain PTW21T revealed an affiliation to the genus Massilia and it shared 98.5 and 98.1 % similarity with Massilianiastensis 5516 S-1T and Massilia tieshanensis TS3T, respectively. Growth occurred at 10-45 °C, pH 4.5-12.5 and NaCl concentrations up to 2 % (w/v). The major fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) and C16 : 0. The predominant respiratory quinone was Q-8. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content of strain PTW21T was 64.6 mol%. The results of DNA-DNA hybridization revealed that strain PTW21T showed 37.4 % relatedness with Massilia niastensis 5516 S-1T and 40.0 % with M. tieshanensis TS3T. Based on phenotypic, chemotaxonomic and phylogenetic differences, strain PTW21T (=CICC 24113T=BCRC 81061T) is proposed as the type strain of novel species of the genus Massilia with the names Massilia neuiana sp. nov.

Rapid nitrification process upgrade coupled with succession of the microbial community in a full-scale municipal wastewater treatment plant (WWTP)

Bioaugmentation was used to upgrade the nitrification process in a full-scale municipal WWTP with an A2/O system. A mixture of nitrifying bacteria was inoculated into the bioreactor for a final concentration of 1% (v/v). The upgrade process took 25 days, and the NH4+-N removals reached 94.6% (increased at least by 75%). The effluent concentrations of COD and NH4+-N stabilized at <30 mg/L and <4 mg/L even when the corresponding influent concentrations were over 300 mg/L and 60 mg/L, which met the first-class requirement of the National Municipal Wastewater Discharge Standards of China (COD ≤ 50 mg/L, NH4+-N ≤ 5 mg/L). The succession of the microbial community showed the enhanced NH4+-N removal efficiency mainly resulted from the persistence of introduced ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), which increased from 0% to 0.4% and from 0.01% to 2.1%, respectively. This bioaugmentation was shown as an effective technology for upgrading or retrofitting conventional systems to tertiary-level.

Research on the enhancement of biological nitrogen removal at low temperatures from ammonium-rich wastewater by the bio-electrocoagulation technology in lab-scale systems, pilot-scale systems and a full-scale industrial wastewater treatment plant

In cold areas, nitrogen removal performance of wastewater treatment plants (WWTP) declines greatly in winter. This paper systematically describes the enhancement effect of a periodic reverse electrocoagulation technology on biological nitrogen removal at low temperatures. The study showed that in the lab-scale systems, the electrocoagulation technology improved the biomass amount, enzyme activity and the amount of nitrogen removal bacteria (Nitrosomonas, Nitrobacter, Paracoccus, Thauera and Enterobacter). This enhanced nitrification and denitrification of activated sludge at low temperatures. In the pilot-scale systems, the electrocoagulation technology increased the relative abundance of cold-adapted microorganisms (Luteimonas and Trueperaceae) at low temperatures. In a full-scale industrial WWTP, comparison of data from winter 2015 and winter 2016 showed that effluent chemical oxygen demand (COD), NH4+-N, and NO3--N reduced by 10.37, 3.84, and 136.43 t, respectively, throughout the winter, after installation of electrocoagulation devices. These results suggest that the electrocoagulation technology is able to improve the performance of activated sludge under low-temperature conditions. This technology provides a new way for upgrading of the performance of WWTPs in cold areas.