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Human living environments and health are seriously affected by the odor produced from fermentation of livestock and poultry manure. In order to reduce the odor pollution caused by livestock and poultry manure, efficient strains were screened and two methods were tried in this study. The orthogonal test design was used to analyze the gas produced by pig manure under different conditions of temperature, time, wheat straw doping amount and calcium carbonate doping amount. Then, according to ammonia, hydrogen sulfide and comprehensive odor removal effects, the high efficiency of deodorizing strains were screened. The results showed that pig manure produced the least odor when the temperature was 20 °C, added 0% calcium carbonate, 20% wheat straw and waited for 48 h. Three strains were screened to inhibit the odor production of pig manure: Paracoccus denitrificans, Bacillus licheniformis and Saccharomyces cerevisiae, showed that their highest removal rate of ammonia and hydrogen sulfide gas could reach 96.58% and 99.74% among them; while for three strains of end-control pig manure stench: Pichia kudriavzevii, P. denitrificans and Bacillus subtilis, the highest removal rate of ammonia and hydrogen sulfide gas reached 85.91% and 90.80% among them. This research provides bacteria resources as the high-efficiency deodorizing function for the source suppression and the end treatment of the odor gas of pig manure, which has high application value for the control of odor pollution.

Polylactic acid has good biodegradability and it is dosage is increasing. Therefore, the degradation of PLA has become a new problem that needs serious management. In this study, the spores of Aspergillus niger were inoculated onto wheat straw/PLA composites containing different contents of sodium alginate, and the mass loss and characterization (microstructure, fourier transform infrared spectroscopy, thermal properties, and X‐ray diffraction) of the composites were detected. The objective was to explore the possibility of degradation of PLA composites by A. niger and the effect of sodium alginate on the degradability of PLA composites. The results showed that when the amount of sodium alginate was 3% and 6%, the mass loss rate of the composites only increased at the initial stage of degradation. However, when the amount of sodium alginate was 9%, the mass loss rate of the composites was significantly increased. It was found that A. niger could colonize the surface of the composites and cause cracks and depressions on the surface by morphological observation. The infrared spectral curve showed that the number of hydroxyl and carbonyl groups in the composites increased after degradation. According to the thermogravimetric curve of the composites, the pyrolysis temperature of the composites with sodium alginate content of 9% increased and the residual mass decreased after degradation. When the amount of sodium alginate was 9%, the crystallinity of the composites was greatly reduced, and it is crystallization zone was easier to degrade compared with other treatments. The results would provide a theoretical support for the rapid degradation of PLA composites.

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The high severity of plant diseases has hampered the implementation of straw incorporation technology in practice. To clarify the relationship between the nitrogen deficiency caused by wheat straw decomposition and Fusarium head blight (FHB) occurrence, five nitrogen levels as 0%, 25%, 50%, 75% and 100% were set to simulate the nitrogen changing after straw incorporated into soil and its effects on the pathogenicity of Fusarium graminearum. Nitrogen starvation degree was characterized by autophagy. Seedling infection and toxin production were used to test pathogenicity. The results showed that biomass of F. graminearum cultured in 25% nitrogen level medium for 72 hr and 120 hr were 0.39 g/ml and 0.29 g/ml, respectively, and were greater than those of other treatments at the same time (p < .05). The spore germination in 0%, 25%, 50% and 75% nitrogen level media were greater than those in 100% nitrogen level medium, in which the total nitrogen deficiency was the greatest (p < .05), reaching 64.5%. Total nitrogen deficiency would lead to F. graminearum autophagic death, while other treatments displayed different starvation responses in F. graminearum. F. graminearum cultured in 25% and 50% nitrogen levels media for 48 and 72 hr or in 75% nitrogen level medium for 168 hr produced more deoxynivalenol (DON). The lesion lengths caused by F. graminearum treated with 25%, 50% and 75% nitrogen levels for 72 hr were 18.33 mm, 15.78 mm and 14.96 mm, respectively, which were significantly longer than the lesions at the 0% (10.57 mm) and 100% (12.18 mm) nitrogen levels. The results indicated that the pathogenicity of F. graminearum was affected by nitrogen levels significantly and partial nitrogen deficiency could prompt the severity of FHB.