Peizhi Xu

Evolution of microbial community diversity and enzymatic activity during composting

The composting of organic material is dependent on microbial activity. However, the dynamics of the microbial community during the composting process remain obscure. Here, denaturing gradient gel electrophoresis of 16S rDNA amplicons in a chicken manure-based compost was applied to characterize the components of the microbial community during the composting process. In addition, the activity of key microbial enzymes was monitored. Arcobacter spp. and Marinospirillum spp. were the dominant species prior to composting, whereas Thermotogae spp. became more strongly represented as the composting process proceeded. Bacillus and Cohnella spp. were featured at various phases. Correlation analysis showed that the diversity of the microbial community was positively correlated with the compost pH, its total nitrogen level, its carbon-to-nitrogen ratio and the activity of protease, and negatively correlated with its organic carbon content and seed germination indices.

Effects of sulphur and Thiobacillus thioparus on cow manure aerobic composting

A simulated aerobic composting experiment was used to explore the effects of sulphur and Thiobacillus thioparus during six manure composting treatments. The addition of sulphur led to a decrease of the pH level within the range 6-6.3, which was lower than the control treatment (CK). The concentration of ammonium nitrogen in T1 (0.25% sulphur), T2 (0.5% sulphur), T3 (0.25% sulphur + T. thioparus) and T4 (0.5% sulphur + T. thioparus) were much higher than the ammonium N in CK. The results indicated that addition of sulphur could increase the concentration of ammonium N and reduce loss of nitrogen. However, excess sulphur had a negative effect on temperature and GI. Addition of T. thioparus could increase concentration of available S, alleviate these negative influences and reduce compost biological toxicity.

Improved composting of poultry feces via supplementation with ammonia oxidizing archaea

Ammonia-oxidizing archaea (AOA) play an important role in the oxidation of ammonia. However, the participation of AOA in the composting process has not been established. The addition of AOA to a compost mix was able to speed up both the onset of the hyperthermic phase and the composting time. The composition of the microflora and the relative abundance were determined by using denaturing gradient gel electrophoresis and quantitative real-time PCR, based on the presence of the archaeal amoA genes. The amplicon profiles allowed some of the major AOA species present in the final compost to be identified, and their relative abundance to be estimated from their amplification intensity. The lower pH during the lower temperature phase of compost served to enhance the nitrogen content of the final compost. The addition of AOA resulted in the expanding diversity of microflora species than that of the natural colonization.

Preparation of a modified flue gas desulphurization residue and its effect on pot sorghum growth and acidic soil amelioration

A modified flue gas desulphurization residue (MFGDR) was prepared and its effects on sorghum growth and acidic soil amelioration were evaluated in this paper. The MFGDR was prepared by calcining a mixture of dry/semi-dry flue gas desulphurization (FGD) residue from a coal-fired power plant, sorted potash feldspar and/or limestone powder. The available nutrients from the MFGDR were determined with 4.91 wt% K(+), 1.15 wt% Mg(2+), 22.4 wt% Ca(2+), 7.01 wt% Si(4+) and 2.07 wt% SO(4)(2-)-S in 0.1 mol L(-1) citric acid solution. Its pH value was held at 9.60 displaying slightly alkaline. The results of sorghum pot growth in both red and crimson acidic soil for 30 days indicated that adding the MFGDR at a dosage of 2 g kg(-1) in total soil weight would increase the growth rate of biomass by 24.3-149% (wet weight basis) and 47.3-157% (dry weight), the stem length and thickness increase by 5.75-22.1% and 4.76-30.9% in contrast with CK treatment for two test cuttings, respectively. The effect on sorghum growth was attributed to the increase of available nutrients, the enhancement of soil pH value and the reduction of aluminum toxicity in acidic soil due to the addition of the MFGDR. The experimental results also suggested that the MFGDR could be effectively used to ameliorate the acidic soil which is widely distributed throughout the southern China.

Fungi diversity from different depths and times in chicken manure waste static aerobic composting

The Dirichlet multinomial mixtures mode was used to analyse illumina sequencing data to reveal both temporal and spatial variations of the fungi community present in the aerobic composting. Results showed that 670 operational taxonomic units (OTUs) were detected, and the dominant phylum was Ascomycota. There were four types of samples fungi communities during the composting process. Samples from the early composting stage were mainly grouped into type I and Saccharomycetales sp. was dominant. Fungi community in the medium composting stage were fallen into type II and III, Sordariales sp. and Acremonium alcalophilum, Saccharomycetales sp. and Scedosporium minutisporum were the dominant OTUs respectively. Samples from the late composting stage were mainly grouped into type IV and Scedosporium minutisporum was the dominant OTU; Scedosporium minutisporum was significantly affected by depth (P<0.05). Results indicate that time and depth both are factors that influence fungi distribution and variation in c waste during static aerobic composting.

The addition of modified attapulgite reduces the emission of nitrous oxide and ammonia from aerobically composted chicken manure

The acceleration of the composting process and the improvement of compost quality have been explored by evaluating the efficacy of various additives, inoculating with specific microorganisms and the application of various biosurfactants. The magnesium-aluminum silicate attapulgite is a low-cost potential composting additive, but its effects on aerobic composting are unknown. This study investigated the effects of attapulgite application on compost production and quality during the aerobic composting of chicken manure. Addition of attapulgite significantly increased the temperature (p < 0.05) while it reduced compost total organic carbon (TOC) and seed germination indices (GIs) throughout the process. Its addition enhanced nitrate concentrations, promoted organic matter degradation, increased seed germination indices, and accelerated the composting process. Interestingly, attapulgite addition did not increase the population of ammonia-oxidizing bacteria. These results suggest that attapulgite is a good additive for the composting industry. Implications: We investigated the addition of two forms of attapulgite during aerobic composting of chicken manure to determine their effects under strict composting environmental parameter control. Our results provides primary evidence that attapulgite may have potential for application in the composting industry. All treatments showed no increase within the first 15 days. However, emissions increased for all treatments within 15–45 days, reaching approximately 6300, 2000, and 4000 mg/m2 from the control, artifactitious attapulgite, and raw attapulgite treatments, respectively.

Effect of Thiobacillus thioparus 1904 and sulphur addition on odour emission during aerobic composting

The effects of sulphur and Thiobacillus thioparus 1904 on odour emissions during composting were studied. Results indicated that the sulphur addition reduced the pH and decreased cumulative emission of ammonia and the nitrogen loss by 47.80% and 44.23%, respectively, but the amount of volatile sulphur compounds (VSCs) and the sulphur loss increased. The addition of T. thioparus 1904 effectively reduced the cumulative emissions of H2S, methyl sulphide, methanethiol, dimethyl disulphide and the sulphur loss by 33.24%, 81.24%, 32.70%, 54.22% and 54.24%, respectively. T. thioparus 1904 also limited the nitrogen loss. The combined application of sulphur and T. thioparus 1904 resulted in the greatest amount of nitrogen retention. The accumulation of ammonia emissions was reduced by 63.33%, and the nitrogen loss was reduced by 71.93%. The combined treatment did not increase the emission of VSCs. The application of sulphur and T. thioparus 1904 may help to control the odour of compost.

Contamination of Paddy Soil by Endocrine-Disrupting Chemicals Affects Soil Microbe Abundance and Diversity

We describe the effect on the population of Eubacteria and Archaea species of adding the endocrine-disrupting chemicals (EDCs) nonylphenol (NP) or dibutylphthalate (DBP) to a typical paddy soil. Fluorescence in-situ hybridization was used to discriminate between the two phyla, and denaturing gradient gel electrophoresis (DGGE) of an amplified fragment of the 16S rRNA locus was used to profile the species present. The population of both Eubacteria and Archaea species was reduced by the presence of NP or DBP, and the deleterious effect was greater for the Eubacteria. The DGGE profiles were used to assess the species diversity in the polluted and non-polluted soil samples. This showed that DBP was less damaging than NP50. It was clear that EDCs can significantly affect paddy soil microbial diversity, both with respect to population size and species representation.

Effects of sulphur and Thiobacillus thioparus 1904 on nitrogen cycle genes during chicken manure aerobic composting

Severe nitrogen (N) loss is a barrier for composting treatment. Since N transformation during composting is closely related to nitrogen loss, the impacts of adding sulphur and Thiobacillus thioparus 1904 to N transformation during composting were investigated in this work. Physicochemical properties and the expression of genes encoding N-related proteins were analysed to evaluate microbiological processes associated with N dynamics. The results indicated that (1) sulphur addition reduced the pH and cumulative NH3 emission, and decreased N losses by 44.23%, while no significant differences were observed in the expression of N cycle-associated genes compared with the control treatment; (2) the application of T. thioparus 1904 increased NO3--N content, reduced N loss by 28.20%, and significantly enhanced the expression of ammonia monooxygenase A (archaeal amoA; AOA) and nitrite oxidoreductase A (nxrA) during the mature phase; (3) the combined application of sulphur and T. thioparus 1904 significantly affected the expression of functional genes related to nitrification and denitrification, which contributed to a reduction in accumulated NH3 emission, an increase in NO4+-N content, and a decrease in N losses by 70.94%. Expression of ammonia monooxygenase A (bacterial amoA; AOB), nxrA and nitrous oxide reductase Z (nosZ) genes in the combined treatment was positively correlated with NO3--N, whereas expression of AOA and accumulation of NH3 were negatively correlated with NO3--N. These results indicate that the combined application of sulphur and T. thioparus 1904 had a significant regulatory effect on N cycle genes and effectively reduced the N loss during composting.

The influence of paddy soil bacterial diversity affected by heavy metals contamination of Dabaoshan Mine

We studied the paddy soil affected by acid drainage of Dabaoshan polymetallic ore in north Guangdong. Using real-time PCR and PCR-DGGE technique, we explored the influence of the soil bacterial community diversity at different degrees of heavy metals contamination of heavy metal and available content. The results showed that: the number of bacterial, paddy soil bacterial diversity, Shannon-Wiener index and evenness index were significantly changed after Cd, Zn, Pb and Cu pollution. The number of bacterial at upstream Liangqiao was significantly lower than the middle Shuilouxia and downstream Upper Dam, reduced by 3.82×107(cells/g soil) and 2.52×109(cells/g soil), respectively. The bacterial diversity, Shannon-Wiener index and evenness index represented as following: the upstream Liangqiao<; middle Shuilouxia<; downstream the Upper Dam. UPGMC cluster analysis showed that the paddy soil bacterial community structure was significantly affected by heavy metals contamination. Therefore, different levels of heavy metals contamination significantly changed the bacterial richness of the soil environment flora and affected the dominant bacterial, thus, changed the diversity of agricultural soil microbial community structure.