The Microbiological Effect Of The Sulfur On The Saline-Alkine Soil And The Research Of The Microbial Preparation

As poor soil, saline-alkaline soil has become a great obstacle of agricultural production in our country, especially in the northwest region, the management and remediation are imperative. Due to the microbial preparation has the abilities of pollution abatement and environmental-friendly property, it has drawn considerable attention in environmental remedy field in recent years. The development of new microbial preparation will surely be effective in the safely environmental treatment and production of green crop without chemical residue.The research focused on the saline-alkaline soil of Ningxia Pingluo in northwestern China, firstly the microflora of the soil which added sulfur was detected, and on this basis, the target sulfur oxidizing bacteria from the experiment soil were isolated and cultured in the laboratory, then they were identified by morphology, physiological and biochemical characteristics and molecular biology; meanwhile, the liquid fermentation optimization and the formula of the preparation were studied; finally, the effect of microbial preparation was determined by pot experiments. The results showed that:1. Among all the treatments, the treatment which applied sulfur improved the properties of the soil compared to the control treatment. With the increase of the amount of sulfur, the microbial effects were also significantly signified. Also in the alkaline soil of Ningxia Pingluo, more improvement was showed after the application of sulfur. In the first year of the experiment, the pH decreased 0.8 to 0.9, but in Weinan, Shaanxi which the soil is relatively high in salt content; pH value decreased only 0.5 to 0.6.After two years, the microflora and pH value were studied again to explore the long-term effect of the sulfur in the saline-alkaline soil in Ningxia Pingluo. The total types of the microbiology were declined while the sulfur utilizing microbiology was increased compare to the result of last time. At the same time, the pH value declined 0.1 again. The result indicated the sulfur has a long-term effect on the remedy of saline-alkaline soil.2. In order to explore a better method to separate sulfur oxidizing bacteria, methods of soil liquid shake flask enrichment and soil enrichment were studied. According to the result, the two worse strains were isolated from soil enrichment method; the better three strains were isolated from the soil liquid shake flask enrichment. It reflected that the previous method was better than the latter one. The conclusion had a reference value.3 target strains were selected from 42 strains after repeated screening. All of them could decrease 2~ 3 pH value of the saline-alkaline soil in liquid flask experiment and decrease 0.8~ 1.1 in the soil experiment. They can be provided as original strains of the microbial preparation in the remediation of saline-alkaline soil.By a series identification of the three strains, using morphological, physiological and biochemical method as well as 16S rDNA sequencing analysis, the result showed that strain S6 could be considered as Arthrobacter sulfonivorans, and S9 and S10 could be considered as Methylophaga alcalica and Bacillus alkalitelluris temporarily. According to the result, the gene sequence similarity were 97.32%,96.32% and 96.78% respectively, they could classify as potential novel species.3. The ferment optimization of strain S6 and S9 were determined by single factor analysis and orthogonal rotatable central composite design respectively, the optimal conditions were: S6: inoculum concentration 107cfu/g, salt 0.5 %, pH 7, temperature 29.1℃。S9: inoculum concentration 107cfu/g, salt 0.9%, pH8.2, temperature 29.1℃。The formula of microbial preparation was studied by dilution plating procedure to determine the number of living bacteria. The optimal formula for both of the strains was: 15% sulfur and 85% of the activated carbon, moisture content 15%.4. In the verified pot experiment of microbial preparation, compared to the control, the treatments which were only with sulfur and added sulfur as well as preparation improved the various indicators, and the development was more significant in the treatment with preparation, especially the treatment with mixed preparation. Above all, the microbial preparation had a positive impact in the pot experiment.