Fermentation Process Optimization And Amplification Of Anti-aflatoxigenic Deep-sea Bacteria

With the increasing attention to aflatoxin contamination food safety,research on aflatoxin prevention and control has increased but aflatoxin inhibitors prepared from deep-sea resources are rare.The purpose of this study is to select the culture medium and culture conditions of deep-sea bacteria which could inhibit aflatoxin synthesis,and to study the optimized fermentation and wettable powder technology.At first,10 kinds of deep-sea bacteria and 8 kinds of common culture medium were screened,and the results were tested by shaking flask fermentation and Tip-culture method.The results showed that the metabolic activity of ISP2,starch casein and M2culture medium was better which inhibition of Aspergillus parasiticus activity can reach more than 90%.And the metabolism of bacteria will be greatly influenced by the culture medium,so the metabolic activity of bacteria can be improved by changing the proportion of medium components.Starch casein and M2 medium were optimized by using DPS uniform design software to obtain two optimization schemes:increasing inhibition rate and reducing cost,such as FA13-M2-N19 and FA13-starch casein-PPM2.The optimized culture medium was screened by seed liquid growth curve and plate colony counting method to obtain the amplified fermentation solution.The magnifying fermentation scheme was using PDM3 as the medium of seed liquid,culturing 18 h as the first inoculation time and 12 h as the second generation inoculation time,and adding 0.01%C5 defoamer.The results showed that the optimized formulation anti-aflatoxigenic rates were higher than that of pre-optimized formulation.In order to prepare bactericides of plant pathogenic fungi from bacterial fermentation liquid,a large amount of liquid bacteria should be spray-dried into powder for storage and transportation easily.Therefore,two kinds of dry powder,FA13-PDM3and FA13-N19,were sprayed into the semi-inhibitory concentration IC₅₀0 of Aspergillus parasitica NFRI-95.The results showed that the IC₅₀0 of sprayed dry powder in enlarged sample was lower than that of the control sodium diacetate preparation.The results of ultrafiltration,alcohol precipitation and ninhydrin detection showed that the main active product of deep-sea bacteria producing and inhibiting aflatoxin synthesis was protein.