The Solid-Liquid Mixed Fermentation Of Agricultural Waste And Surfacant And Antioxidant Activities Of Their Fermrnts

Utilization of microbiological fermentation techniques for value-added processing agricultural by-products and for resource-oriented recycling agricultural wastes is one of hot practices in modern agriculutry worlwidely.Some Bacillus species,which are common in nature as plant-growth promoting and biological control bacteria,are already used in production of biofertlizer and biopesticde products,but their potential use as new additives in fertilizers,food and feeds is less studied.Previous studies showed that lipopeptides from metabolic producs of Bacillus amyloliquefaciens XZ-173 were excellent in promotion of plant growth and control of plant diseases.This study was aimed to explore the bio-surfactant activities and antioxiditive properties of the ferment products with XZ-173 for development of new additives to be used in fertilizers,food and feeds.The objectives of this study were:(1)to investigate the promoting effect of ferment extracts from XZ-173 on tomato and corn;(2)to establish a laboratory solid-liquid mixing fermentation process for using soybean powder,rice hulls and other agricultural products and wastes with XZ-173 to produce the additives with good bio-surfactant activies and antioxidative properties;(3)to test the bio-surfactant activities and antioxidant activities of ferment extracts from different extraction methods;and(4)to optimize the antioxidant fermentation conditions.The main research results of this study are as follows:(1)Results from pot experiment showed that the foliar fertilizer formulated by surfactant extract(SFF)from solid-state fermentation of soybean powder and rice straw with XZ-173 had significant promoting effect on growth of tomato and corn.As compared under the same growing conditions,the SFF increased the plant hight,stem diameter,leaf chlorophyll content and total biomass dry weight of tomato by 30.5%,20.8%,9.1%,and 65.4%,respectively,while increased thest indices of corn by 36.21%,68.2%,42.2%and 115.8%,respectively.(2)A laboratory solid-liquid mixing fermentation process for using soybean powder,rice hulls and other agricultural products and wastes with XZ-173 to produce the additives with good bio-surfactant activies was extablished.Six kinds of agricultural by-products and wastes(soybean powder,soybean meal,wheat bran,rice straw,rice husk,and corn powder)as main fermentation substrates and five types of fermentation auxiliary substrates were tested and the results showed that soybean powder and rice husk were suitable for production of bio-surfactants.The optimization results showed that the optimal substrates in a 150 mL system were composed of 2.63 g of soybean powder,4.49 g of rice husk,0.1 g of glucose,0.09 g of urea and 1 mL of inorganic salt solution,while the optimal conditions were initial pH 7.5,50 mL of water added,15%inoculum size,170 rpm of rotation speed,30? of constant temperature and 60 h of incubation time.Under the optimized conditions,the yield of bio-surfactant crud product(SCP)reached to 106.11 mg/gds.(3)The bio-surfactant activities and antioxidant activities of ferment extracts were significantly different from extraction methods used.The fermentation crude extract(FCE)and the bio-surfactant crude product(SCP)were obtained by suction filtration and acid precipitation method,respectively.Analysis results show that SCP had better surface activity and antibacterial properties than FCE,but FCE has better antioxidant properties than SCP.When the concentration was 2.0 mg/mL,the clearance rates of FCE to ABTS+radical,DPPH radical,hydroxyl radical and superoxide anion reached 33.88%,40.07%,29%and 88.5%,respectively.Compared with SCP,FCE also showed higher reduction capacity and total antioxidant capacity.(4)A laboratory solid-liquid mixing fermentation process for using wheat bran and rice straw with XZ-173 to produce extracts with good antioxidant activities was extablished.Six kinds of agricultural by-products and wastes(soybean powder,soybean meal,wheat bran,rice straw,rice husk and corn powder)as main fermentation substrates and five types of fermentation auxiliary substrates were tested and the results showed that wheat bran and rice straw were suitable for production of the extract with high antioxidant activities.The optimization results showed that the optimal substrates in a 150 mL system were composed of 2.62 g of wheat bran,2.83 g of rice straw,3 mL of inorganic salt,0.11 g of sucrose,0.11 g of yeast extract,while the optimal conditions were 59.44 mL of water added,2.97 mL(5%,V/V)of inoculum,initial pH 7.5,180 rpm of rotation speed,33? of constant temperature,and 60 h of incubation time.Under the optimized conditions,DPPH clearance rate of the ferment extracts reached a maximum of 34.24%,which was near the predicted value of 34.64%.In conclusion,the ferment extract with good bio-surfactant activities was obtained by solid-liquid mixing fermentation of soybean powder and rice hulls with XZ-173,while the ferment extract that could remove multiple oxidative radicals was obtained by solid-liquid mixing fermentation of wheat bran and rice straw with XZ-173.These ferment extracts had potential to be used as a new natural additive in the development of new fertilizer,food and feed products.