Bioactivity Analyses And Fermentation Process Optimizations Of Three Strains Of Deep-sea Fungi

The ocean covers more than 70%of the earth's surface,and the deep sea accounts for 50%of the earth's surface area.The deep-sea microorganisms have been living in extreme special environments such as high pressure,darkness,oligotrophic,low temperature,hypoxia,and high salt concentration for a long time.This also determines that deep-sea microorganisms will have more unique metabolic pathways and morphological characteristics than those on land.Substances produced by deep-sea microorganisms also exhibit diverse activities and novel structures,which allows deep-sea microorganisms to play more new uses.Fungal polysaccharides have good activities of moisture absorption,anti-oxidation,immunity enhancement and bacteriostasis,and have good affinity with human skin.In this paper,the antioxidative and hygroscopic activities of extracellular polysaccharide from Beauveria bassiana T2-2,which was isolated from the volcanic sediments of the East Pacific Ocean,were studied to explore its application potential in cosmetics and health products,and the fermentation parameters of Beauveria bassiana were optimized to provide basic support for its industrial application.The molecular weight,composition and biological activity of T2-2 polysaccharide were determined.GPC results showed that the extracellular polysaccharide produced by T2-2 was a kind of mixed polysaccharide composed of three polysaccharide components,with a weight average molecular weight of 2.736×10~3 da.The results of monosaccharide composition showed that T2-2 polysaccharide was mainly composed of glucose,mannose and galactose.Antioxidant experiments showed that T2-2polysaccharide had better scavenging effect of DPPH and superoxide anion radicals.At the concentration of 2 mg/ml,the scavenging rate of polysaccharide to two kinds of free radicals was 89.1%and 80.2%,respectively.The results showed that the moisture absorption rate of T2-2 polysaccharide was 31%and 90%at the relative humidity of 43%and 81%.The single factor experiment and orthogonal experiment were used to optimize the sugar production medium and conditions of Beauveria bassiana T2-2.The content of polysaccharide in the fermentation broth after optimization was 0.92±0.02 g/L,which was 46.2%higher than that before optimization.Yeast feed additive is a new type of green and pollution-free microecological feed additive.In this paper,using the sediment samples from the ocean voyage,we screened out high-quality yeast strains with digestive enzyme production and anti Aquatic Pathogenic bacteria activity,optimized the fermentation parameters of yeast,and carried out the drying experiment of fermentation liquid,so as to finally apply the deep sea yeast to aquatic feed additive Provide technical support.Finally,23 strains of lipase producing yeast,4 strains of Cellulase Producing Yeast,8 strains of protease producing yeast,11 strains of amylase producing yeast,3 strains of Vibrio alginolyticus,4 strains of Vibrio parahaemolyticus,4 strains of Vibrio Campylobacter and 1 strain of Aeromonas hydrophila were screened.The activity of two yeast strains A-6 and A-25 was better.The identification results showed that the yeast strains a-6and A-25 were sporidiobolus pararoseus and Cryptococcus rajasthanensis,respectively.Single factor experiment and orthogonal experiment were used to optimize the fermentation conditions of A-6 and A-25.The dry weight of yeast cells was 38.1±0.2 g/L and 34.3±0.2 g/L respectively,which was 36.1%and 29.4%higher than before.Drying experiments of fermentation broth were carried out,and finally the drying method of yeast fermentation liquid was determined.