The Primary Research On Fermentation Technical Parameters And Determination Of Part Biological Functions Of Two Serratia Spp.

The study was focused on Serratia spp.Z10isolated from the stems of Polygonum viviparum and X4isolated from the leaves of Kobreasia capillifolia on the East Qilian Mountains Alpine grassland. Preliminary study on biological functions including the capacity of secreting indole-3-acetic, phosphorus-dissolving, antibacterial mechanism.Else, the fermentation conditions of Serratia sp.X4in10L fermentor and the effects of temperature, medium pH, ventilation and stirring speed were studied. The results were as follows:1. Determination the capability of secretion of IAAUsing the methods of Salkowski colorimetric, the result showed that the concentration of IAA respectively was63.82mg/L、50.74mg/L in the King medium containing100mg/l tryptophan for Z10and X4, but in the King medium without tryptophan, the concentration of IAA respectively was5.38mg/L、4.95mg/L for Z10and X4. The appropriate dilute concentration may promote the germination rate of seeds and seedlings of the plant height, when the dilute concentration was1:30, bacterium liquid of Z10and X4inhibited wheat and tomato seed germination, when the dilute concentration was1:40and1:50, two strains were able to significantly promote seed germination. Else, the dilute concentration was1:50, the effect of wheat and oat growth-promoting was the most significant for Z10and X4fermentation liquid. Z10and X4in1:40diluted concentrations could promote the growth of tomato and alfalfa.2. Determination the capability of phosphorus-solubilizingUsing the methods phosphorus cycle, the result showed that there were obvious phosphor-us solubling rings in Pikovaskaia inorganic medium and Meng Jinna organic medium,TheD/d value of Z10was respectively3.16、3.23in Pikovaskaia inorganic medium and was4.0and4.31in Meng Jinna organic medium. The increments of available phosphorus of Z10and X4respectively were88.63mg/l,86.05mg/l on Pikovaskaia and19.37mg/l,14.39mg/l on Mengjinna organic culture medium. Meanwhile, pH values were lower in the inorganic or organic culture medium. Enzymes played major roles in dissolving organic phosphorus, acid and enzymes in the interaction was more obvious in the process of dissolving inorganic phosphorus.3. Determination the antibacterial effect on plant pathogenic fungiUsing the method of dual culture in Petri dish, The result showed that Z10and X4could inhabit f-our plant pathogenic fungis such as Rhizoctonia solani, Sclerotinia sclerntiorum,Botrytis cinerea, Fusarium oxysporum. Microscopic observation showed the mycelial growthof morphological was abnormal, dilated, distorted, protoplasm spillover, final hyphae breaked.There were correlated between the inhibition rate and dilute concentration of bacteria liquidZ10and X4. When the concentration of Z10was6.25μl/ml, the inhibitions rate was biggeston Rhizoctonia solani, was37.1%. While the concentration was100μl/ml, The inhibition rate was65.3%, and EC50was26.6μl/ml. When the concentration of X4was6.25μl/ml, the inhibitions on Sclerotinia sclerntiorum were biggest and the inhibition rate37.0%, EC50was42.7μl/ml. While the concentration was100μl/ml, the inhibition rate on Fusarium oxysporumis59.5%, and EC50was64.7μl/ml.There were pale yellow extract of strains Z10and X4use of rotary evaporation instrument through two methods (i.e., acid precipitation or organic solvent extraction method). Inhibitory substances produced by strains Z10and X4on the heat was unstable, when pH between6and8, Z10and X4antibacterial activity reached maximum, UV light time on the antibacterialactivity of strains Z10and X4had a minor effect.4. The study of fermentation technology parameters on Serratia sp. X4The study was focused on fermentation parameters. The results showed that the optimal fermentation parameters of Serratia sp.X4were temperature28℃,pH7.0, ventilated volume1000L/h, rotate speed200r/min, and the number of live bacteria reached the maximum. The growth curve was made by10L fermentation tank test in the optimum conditions.It showed that the bacteria arrives logarithmic phase and stabilization phase respectively after4hours and32 hours, the maximal number of live bacteria was1.195×1012cfu/ml in the fermentation liquid.Ultimately initial determine the optimum fermentation time of X4fermentation was between32h and36h.