Liqiang Meng

Feasibility of co-composting of sewage sludge, spent mushroom substrate and wheat straw.

In this study, the lab-scale co-composting of sewage sludge (SS) with mushroom substrate (SMS) and wheat straw (WS) conducted for 20days was evaluated. The addition of SMS evidently increased CO2 production and dehydrogenase activity. The combined addition of SMS and WS significantly improved the compost quality in terms of temperature, organic matter degradation and germination index, especially, reduced 21.9% of NH3 emission. Thats because SMS and WS possessed the complementarity of free air space and contained plenty of degradable carbon source. The SMS could create a comfortable environment for the nitrifying bacteria and improve nitrification. The carbohydrates from combined addition of SMS and WS could be utilized by thermophilic microorganisms, stimulate ammonia assimilation and reduce NH3 emission. These results suggested that adding SMS and WS could not only improve the degradation of organic matter and the quality of compost product, but also stimulate ammonia assimilation and reduce ammonia emission.

Effects of sucrose amendment on ammonia assimilation during sewage sludge composting

The aim of this study was to evaluate the laboratory-scale composting of sewage sludge and pumice mixtures that were amended with sucrose. The variation in temperature, pH, NH4(+)-N, ammonia emission, bacterial community, ammonia assimilating bacteria (AAB) populations and enzymatic activity related to ammonia assimilation were detected. The addition of sucrose increased the AAB population by 2.5-3.5 times, reduced ammonia emission by 24.7-31.1% compared with the control treatment, and promoted the growth of Bacillus and Wautersiella. The activities of glutamate dehydrogenase (GDH), glutamate synthase (GS) and glutamine synthetase (GOGAT), were enhanced by the addition of sucrose. GDH made a substantial contribution to ammonia assimilation when the ammonia concentration was high (⩾1.5g/kg) in the thermophilic phase. The GS/GOGAT cycle played an important role at low ammonia concentrations (⩽1.1g/kg) in the cooling phase. These results suggested that adding sucrose to sludge compost could promote ammonia assimilation and reduce ammonia emission.

Isolation and characterization of antifungal lipopeptides produced by endophytic Bacillus amyloliquefaciens TF28

Bacillus amyloliquefaciens TF28, an endophytic bacterium isolated from soybean root, showed strong antifungal activity in vitro. In this study, crude lipopeptides were extracted with methanol from the precipitate by adding concentrated HCl to culture filtrate. They exhibited highest antifungal activity against the rice bakanae fungus Fusarium moniliforme. Besides F. moniliforme, the crude lipopeptides also inhibited the growth of other phytopathogens such as Botrytis cinerea, Fusarium oxysporum etc. Microscopic analysis found that the crude lipopetides distorted hyphae and spore of F. moniliforme. The crude lipopetides were very stable to heat and insensitive to pH. They still retained strong antifungal activity after treatment at pH values ranging from 2 to 12 for 24 h or at 100°C for 30 min. Therefore, it is a candidate biocontrol agent for rice bakanae controlling. Biologically active fractions were isolated by high-performance liquid chromatography (HPLC). A component of a molecular weight of 1057 Da was identified as iturin A after electrospray ionization quadrupole time of flight tandem mass spectrometry analysis (ESI-Q-TOF-MS/MS).

Microbial community composition and function in a pilot-scale anaerobic-anoxic-aerobic combined process for the treatment of traditional Chinese medicine wastewater

Biodegradation of traditional Chinese medicine (TCM) wastewater was investigated in a pilot-scale anaerobic-anoxic-aerobic combined process, which was composed of an expanded granular sludge blanket (EGSB) reactor, a hydrolysis acidification (HA) reactor and a biological contact oxidation (BCO) reactor. In stable stage, the average values of COD and color in the combined process effluent were 45.7mgL-1 and 13 times, respectively. Excellent linear relations (R2>0.915) were achieved between color and UV254 at three color levels. Comprehensive community structures of the combined process were analysed by Illumina MiSeq Sequencing, which revealed that microbial community in the aerobic reactor had the greatest diversity and richness. Bacteroidetes, Firmicutes and Proteobacteria were dominant phyla in the three reactors, and Bacteroidales, Geobacter, ZB2 were the predominant functional microorganisms in the anaerobic, anoxic and aerobic reactors, respectively. Good removal efficiencies and presence of core microorganisms confirmed that the combined process was feasible for treating TCM wastewater.

Ammonium removal at low temperature by a newly isolated heterotrophic nitrifying and aerobic denitrifying bacterium Pseudomonas fluorescens wsw-1001

A heterotrophic nitrifier wsw-1001 was isolated from Songhua River and identified as Pseudomonas fluorescens. Ammonium removal by the strain at low temperature was investigated. The effect of initial ammonium concentration (from 5 to 1000 mg/L) and culture temperature (from 4°C to 30°C) on ammonium removal efficiency was studied. Biodegradation product, , , N2, N2O and intercellular N were monitored. The results indicated that the strain had potential for water and wastewater treatment. Ammonium could be removed by the strain at low temperature. Ammonium removal efficiency increased with temperature from 4°C to 20°C and decreased with ammonium concentration from 5 to 1000 mg/L. The strain exhibited a capability of heterotrophic nitrification and aerobic denitrification using as the sole nitrogen source at 8°C. and were reduced by the strain. Nitrogen balance analysis in the presence of 39.7 mg/L indicated that 71.2% was removed by converting to N2 (46.3%) and assimilating as biomass (42.5%). Substances such as , and N2O were detected at very low concentrations. Ammonium mono-oxygenase, hydroxylamine oxidase, nitrite reductase and nitrate reductase activity were measured. The ammonium removal pathway of the strain was speculated to be .

Improving sewage sludge composting by addition of spent mushroom substrate and sucrose

The effects of spent mushroom substrate (SMS) and sucrose (S) amendment on emissions of nitrogenous gas (mainly NH3 and N2O) and end products quality of sewage sludge (SS) composting were evaluated. Five treatments were composted for 20 days in laboratory-scale using SS with different dosages of SMS and S, without additive amended treatment used as control. The results indicated that SMS amendments especially combination with S promoted dehydrogenase activity, CO2 production, organic matter degradation and humification in the composting, and maturity indices of composting also showed that the 30%SMS+2%S treatment could be much more appropriate to improve the composting process, such as total Kjeldahl nitrogen, nitrification index, humic acids/fulvic acids ratio and germination index, while the emissions of NH3 and N2O were reduced by 34.1% and 86.2%, respectively. These results shown that the moderate addition of SMS and S could improve the compost maturity and reduce nitrogenous gas emission.

Design, synthesis and antibacterial activity of a novel hybrid antimicrobial peptide LFM23

Antimicrobial peptides produced by many tissues and cell types of invertebrates, insects and humans as part of their innate immune system, have received increasing attention as potential candidates due to their administration as pharmaceutical agents. In the present study, a novel hybrid antimicrobial peptide LFM23 consisting of 23 amino acid residues was designed based on the primary sequences of bovine lactoferricin (LfcinB) and melittin. The peptide was synthesized by chemical method of solidphase synthesis with a purity of more than 98% after reverse phase high performance liquid chromatography. Antimicrobial activity assay showed that LFM23 had strong antibacterial abilities, and the minimum inhibitory concentrations against Escherichia coli AT CC25922, Salmonella typhimurium ATCC12291, Pseudomonas aeruginosa ATCC27853, Staphylococcus aureus ATCC25923, Pichia pastoris GS115, were 32, 32, 64, 32 and 256 μg/ml, respectively. The hemolytic assays indicated that LFM23 had no hemolytic action in vitro at antimicrobial concentration. The results demonstrate that the peptide LFM23 has a good application prospect as clinically useful antimicrobial agents.