Study On The Decomposition Characteristics Of Corn Stalk Treated By Microorganisms

In China, agricultural waste such as straws is one of the most important biosources for econonmical development and environmental protection, due to the great amount of straws production. However straw are difficulty for decomposition because of its unique characteristics, which limit the further recycling and unitization as resources. Traditional treatment cause not only straws waste, but also lead to some negative effect such as atmospheric pollution, soil hardening, fertility declination and so on. Thus the biotreatment of straws is the best way due to less pollution, higher efficiency, which is better for industrial production. In the past long time of research and practical experience, people paid their attention on the decomposition of cellulose with neglecting the aspect of decomposition of lignin, which is the main limite-rate factor. In nature, the completely decomposition of lignin is the final results of the interactions among fungi, actinomycete, bacterial and microbial communities, in which fungi plays a key role. Currently, the white rot fungus is the best choice for lignin decomposition. Meanwhile the process of straws decomposition is finished due to the effect of series enzymes in the process of microbial metabolism, which needs the participation of synergism of enzymes. Desertification has become one of most serious ecological environment problem in China. Sandy soil with large particles and loosened texture have poor soil fertility and water conservation, low content of organic matter and nutrient. It not only causes N, P losing during agricultural production but also leads to area source pollution and water eutrophication, thus induce the deterioration of ecological environment. From this viewpoint, it's prospectively significant to treat straws by combination application of the cellulose decomposition bacterium and lignin decomposition bacterium.In the study,0.5cm,1-3cm, and 4-5cm corn straws were treated with two kinds of methods: independent fermentation with Phanerochaete chrysosporium and synergic fermentation with mixtures of Phanerochaete chrysosporium and Penicillium. In independent fermentation, different sizes of corn straws were fostered in 30℃after inoculated with Phanerochaete chrysosporium which had been cultivated for 5 days, and then analysed respectively in 5,10,15,20,25,30,35, and 40 d. In synergic fermentation, Phanerochaete chrysosporium was firstly inoculated into corn straws, and then Penicillium (1cm x 1cm) was inoculated after 15,20, and 25 d, respectively; the samples were analyzed after inoculation of Penicillium by 5,10,15, and 20 d. The characteristics of decomposition and characterizations of products in the fermentation process were studied, and the research achievements were summarized as follows.1. The decomposition degrees of corn straws with three sizes (0.5cm,1-3cm, and 4-5cm) fermented with Phanerochaele chrysosporium were various, and relationship between decomposition rate and time, and the sizes of corn straws were significant. The degree of lignin decomposition and humification size increased with the larger size. After 25-d fermination, the decomposition rate of straws and lignin were significantly towards constant, and the optimal size was 4-5 cm. the carboxyl group in decomposition products increased with the decreasing of phenolic hydroxyl group, which indicated the decomposition was a oxidation process, and the phenolic hydroxyl oxidated into carboxyl.2. Antagonistic experiment in flat plate was processed through addition of Phanerochaele chiysosporium and Penicillium for lignin decomposition, which found the Penicillium was a dvantageous bacterial with a inhibitory effect on Phanerochaete chrysosporium through competition. Thus, it needed two-step method for mixture of the above bacterials to straws decomposition by fermination, which Phanerochaete chrysosporium was inoculated firstly, and then inoculated Penicillium.3. Corn straws fermentation with mixed bacterial were proceeded under natural temperature, we found the degradation rate of 0.5 cm straw reached highest point in 45 d with combination of P25 and F20. The content of humic acid decreased after inoculation of Penicillium, indicating that Penicillium was not conducive to the formation of humic acid. And the reduction of phenolic hydroxyl proved that cellulose had been effectively degraded after inoculation of Penicillium.4. Through the scanning electronic microscope (SEM) analysis, the apparent structures of unfermented corn straws were tight and uniform in comparison with the structures of straws treated by bacterial combination application, which showed the destruction of apparent structures with the existence of many cracks and hollows. Furthermore, the treatment effect of the latter one (combination treatment) was better than the former.5. Comprised with IR spectra of straws after and before fermentation, it was found that the carbohydrate such as cellulose, lignin and hemicellulose decomposition occur, which caused the decreasing hydroxyl and methylene, meanwhile indicated the phenolic was oxidized to quinone. In addition, the protein and amino acid decomposed into amide and inorganic materials including nitrate and ammonium salts.