Study On Culture Technology And Application Effect Of Rhodopseudomonas Palustris R2

Rhodopseudomonas palustris,a type of photosynthetic bacteria,is one of the oldest microorganisms on Earth.It is widely used in sewage treatment,single cell protein production and other fields because of Its bacteria are rich in many kinds of bioactive substances,rich in nutrients,and have strong adaptability.Recent research has found that Rhodopseudomonas palustris has a good promoting effect on the growth of crops,Therefore,it has been widely used in microbial fertilizers.The traditional Rhodopseudomonas palustris has a long culture cycle,serious energy consumption and high cost,and does not meet the needs of large-scale culture.In this experiment,Rhodopseudomonas palustris R2 was taken as the research object.Based on the traditional fermentation process of photosynthetic bacteria,the culture conditions and culture medium were optimized.In order to improve the concentration of bacterial solution of Rhodopseudomonas palustris and shorten the period of culture,the temperature,light intensity,initial pH and inoculum quantity of Rhodopseudomonas palustris R2 were optimized by single factor experiment in this paper.It was found that Rhodopseudomonas palustris had the best growth when the temperature was 30°C,light intensity was 7000 lux,initial pH was 7-8,and inoculation amount was 15-20%.In order to reduce production cost,the feasibility of using LED lamp instead of incandescent lamp as light source to culture Rhodopseudomonas palustris was verified by experiments.The results showed that the growth effect of Rhodopseudomonas palustris under LED light source is basically the same as that under incandescent light source.The growth of Rhodopseudomonas palustris under incandescent lamp was better than that under LED light source in the early stage of culture.But after cultivating for four days into the stable period,the concentration of bacteria solution under the LED light source was higher.A comparative experiment optimized the carbon source in Rhodopseudomonas palustris medium.The carbon source for the growth of Rhodopseudomonas palustris was optimized by comparative experiment.Based on this,the most suitable amount of carbon source,ammonium chloride,yeast extract,sodium chloride,magnesium sulfate and potassium dihydrogen phosphate was optimized by single factor experiment.The experiment found that carbon source,ammonium chloride and yeast extract were major factors affecting the growth of Rhodopseudomonas palustris.The medium was optimized by Box-Behnken method.The optimum medium formulation was obtained by response surface analysis.The formulation is sodium propionate 7.00g/L and ammonium chloride 1.24g/L,Yeast extract 1.06g/L,sodium chloride 1g/L,magnesium sulfate 0.25g/L,potassium dihydrogen phosphate 0.25g/L.Under these conditions,the concentration of Rhodopseudomonas palustris could reach 2.5 billion cfu/mL after three-days culture.Cultivate the fourth day into the stable period,the bacterial concentration reached 3.05 billion cfu/ mL,which greatly increased the yield and shortened the production cycle.In the large-scale production of Rhodopseudomonas palustris,it often happens that the bacterial liquid is not treated in time to lead to the bacterial liquid accumulation.In order to ease the storage pressure,On the basis of references,four flocculants were selected to test the flocculation effect of Pseudomonas palustris solution.The four flocculants were aluminum sulfate,alum,aluminum chloride,and polyaluminum chloride,and the amount of flocculant was also studied preliminarily in this paper.The results showed that the best flocculant was polyaluminium chloride,the flocculation effect can reach 100% when the dosage was0.01mol/L.In order to verify the application effect of Rhodopseudomonas palustris in agriculture,the effects of different concentrations of bacterial solution of Rhodopseudomonas palustris on growth index of cucumber seedlings and fruit quality of cucumber were studied.The results showed that Rhodopseudomonas palustris could significantly increase the plant height and stem diameter of cucumber and the content of leaves chlorophyll of cucumber,and the effect of 150-times dilution was the best.Rhodopseudomonas palustris could significantly increase the content of Vc in cucumber fruit,reduce the content of nitrate in cucumber fruit,and apply100-times dilution bacteria solution to the best effect.