Fabao Zhang’s research while affiliated with Guangdong Academy of Agricultural Sciences and other places

Fusarium wilt is one of the most serious banana diseases. It is caused by the soil-borne pathogen Fusarium oxysporum f. sp. cubense (Foc). The key accepted reasons for disease break-outs are the increasing number of pathogens in soil and gradual soil acidification according to published reports. Few studies have reported management methods to control these two aspects at the same time. In this study, a novel improved biological control method, combined acid soil ameliorant (ASA) with biofertilizer (BIO), was applied to manage Fusarium wilt under greenhouse conditions. A biocontrol agent, Bacillus velezensis H-6, was isolated and used for producing biofertilizer BIO6 for pot experiments. Combined ASA with BIO6 (treatments OBIO6 and ABIO6) showed greater biocontrol efficacy compared with individual treatments by 63.3% and 66.7%, respectively. They also increased rhizosphere soil pH from 4.50 to 4.89 and 5.52, respectively. Correlation analysis showed that the Foc population and Fusarium wilt disease incidence (DI) were both significantly (P < 0.05) negatively correlated with ∆pH in the rhizosphere, contents of NH4-N and organic matter (OM), and populations of bacteria and actinomycetes. Furthermore, ∆pH was significantly positively correlated with content of OM and populations of bacteria and actinomycetes, while it was negatively correlated with content of NO3-N and population of fungi. In conclusion, our novel improved biological control method revealed a greater potential to control Fusarium wilt of banana, and the effect might be a result of improving soil acid-alkali conditions to decrease the density of pathogen and manipulating the soil microbial community.

This paper focused on the ammonium removal from the digested effluent of swine wastewater (DESW) via MAP precipitation using the residue from magnesium-hydroxide flue gas desulfurization (MFGD) process as a Mg source. The MAP precipitation was proceeded in a 500-mL beaker with a magnetic stirrer. It was found that around 60% of ammonium in the DESW was removed at pH 9.5, HRT 10min and the P:Mg:N molar ratio of 0.6:0.7:1. The NH4⁺ concentration (183.2mg/L) in the DESW after MAP precipitation was lower than 200mgL⁻¹, being alternative for the downstream biological process. A low content of PO4³⁻ (3.64mgL⁻¹) and a high concentration of Mg²⁺ (67.17mgL⁻¹) were also observed in the solution. The main composition of the precipitate was proved to be MAP via XRD and SEM-EDX analysis. Besides, the total chemical cost was saved by 29.17% using the MFGD residue as a Mg source instead of the commercial MgCl2·6H2O. Hence, reusing MFGD residue as a Mg source to remove ammonium from the DESW was feasible with cost saving, resource recovery and environment protection. © 2017 The Korean Society of Industrial and Engineering Chemistry.

Many of the areas dominated by acid sulfate (AS) soils in southern China have been reclaimed for rice cultivation and represent an important source of agricultural production and food security for the local population. In this study, we examined the abundance and partitioning of Fe, Mn, Zn, Cu, and Al in both rice paddy fields and uncultivated fields by using a six-step sequential extraction procedure. Rice cultivation significantly reduced acidity levels at soil depths of 0–100 cm, but acidity at depths of 100–140 cm increased significantly. A substantial loss of Mn in the oxide and acidified soil layer (0–100 cm) compared to the underlying parent material was observed, but there were few changes in the concentrations of Fe and Zn throughout the soil profile. However, both Cu and Al were substantially enriched in the superficial soil (0–40 cm) compared to the underlying subsoil (40–140 cm). In general, leaching of Fe, Mn, and Al was higher in the paddy fields because of intensified irrigation and flood conditions, whereas accumulation of Cu, mainly in the form of “acid soluble” and “crystalline iron oxide” Cu, was higher in the paddy fields than in the uncultivated fields. The most marked declines in metal concentrations occurred in the “labile” and “acid soluble” fractions, as a result of rice cultivation, which increased leaching of the readily mobilized “labile” and “acid soluble” fractions of heavy metals in these soils.

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.

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.

The aim of this study was to screen hemicellulose degrading microorganisms. The methods used to screen the effective strains included hydrolysis spot diameter measurement of hemicellulose plate and extracellular enzyme activity. The methods used to identify the strains included culture characteristics, morphological, physiological-biochemical characteristics and molecular biological methods. We isolated 4 actinomycetes (NA9, NA10, NA12 and NA13), 2 fungi (NF1 and NF7) with hemicellulose degrading ability and no antagonistic effect among them. The hemicellulose degrading activity of 4 actinomyces (NA9, NA10, NA12 and NA13) was 217.6, 229.8, 221.1 and 211.8 U/mL. The hemicellulose degrading activity of 2 fungi (NF1 and NF7) was 217.7 and 244.2 U/mL. The hemicellulose degrading activity of complex microbial system was 299.0 U/mL. NA9, NA10, NA12 and NA13 were Streptomyces costaricanus; NF1 was Aspergillus candidus and NF7 was Tarlaromyces flavus. the 4 actinomyces and 2 fungi screened have high hemicelluloses enzyme activity. These strains have good application value and more research value.

Unlabelled: 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.

The aim of this study was to screen microorganisms that could degrade rice straw. We used selective medium to screen strains and determined straw fracture tension strength, weight loss, lignocellulose decomposition rate and extracellular enzyme activity as re-screening methods after 10 days shake flask culture. We isolated two antinomycetes (A3 and A6), the highest cellulose enzyme activity of holoenzyme, beta3-Glucosidase, endonuclease and exonclease for A3 were 12.84, 6.23, 24.56 and 14.00 U/mL, and for A6 12.85, 6.53, 17.80 and 18.80 U/mL. The hemicelluloses enzyme activity was 83.05 for A3 and 52.98 U/mL for A6. Both strains belonged to Streptomyces. With 10 days' treatment, inoculated straws showed a decrease of straw fracture tension strength by 62.67% (A3) and 66.67% (A6), while weight loss of straw was 31.50% (A3) and 35.83% (A6). A3's decomposition rate of cellulose, hemicellulose and lignin was 38.73% , 33.16% and 20.68% , and 47.69% , 28.64% and 22.59% for A6. Antinomycetes A3 and A6 could degrad cellulose, hemicellulose and lignin.

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.