Study On The Mixed Fermentation Of Feather Powder By Pseudomonas Sp.W7 And Pseudomonas Sp.H

Feather powder can be used as a high protein content of livestock and poultry feed,whose protein content is to 85% of dry weight.Keratin is the main protein in feather powder,its molecular structure is complex and coexist with about 10% of adipose,whose high level of fat prevents feathers from being degraded by microorganisms.The degradation of feathers by microorganisms,making it difficult to be degraded by conventional proteases such as pepsin,papain and others,and resulting in a lower digestibility rate,so the proportion of the feed cannot be more than 5%,otherwise it will lead to livestock malnutrition.Finding suitable feather protein degradation methods have great significance to improve the digestibility,and make use of feather powder protein resources.Pseudomonas sp.W7 and Pseudomonas sp.H8 are two strains of cold-resistant bacteria isolated from domestic sewage.The optimum growth temperature of Pseudomonas sp.W7 is 25 ℃,and the optimum growth temperature of Pseudomonas sp.H8 is 10 ℃.Pseudomonas sp.H8 has the activity of producing low temperature lipase.Pseudomonas sp.W7 has the ability to produce low-temperature protease,The low-temperature protease has the ability to hydrolyze bovine protein,soybean protein and milk protein,but the degradation of its keratin has not been reported.In this paper,Pseudomonas sp.W7 and Pseudomonas sp.H8 were used to degrade feather powder respectively,At the same time,we studied the two strains of mixed fermentation to degrade feather powder,analyzed the fermentation products of different conditions,and explored the effective methods of low temperature microbial degradation of feathers,so as to provide a new way to improve the utilization of feather powder.Firstly,we studied the fermentation of Pseudomonas sp.W7,and we selected four factors: fermentation temperature,fermentation time,bacteria quantity and shaking speed,Through the single factor experiment and the orthogonal experiment,the optimum conditions for the degradation of feather powder with Pseudomonas sp.W7 are determined: the fermentation temperature was 30 ℃,the fermentation time was 8 days,the bacteria quantity was 1.5%,the shaking speed was 140r·min-1,and the hydrolysis rate of feather powder was 23.62%,the in vitro digestibility of residue was 63.54%,and the content of soluble protein was 575mg·L-1.The fermentation research of Pseudomonas sp.H8 degrade feather powder,the results show that when using Pseudomonas sp.H8 to degrade feather powder,it only works on fat,but the effect of protein degradation is not obvious.We used Pseudomonas sp.W7 and Pseudomonas sp.H8 compound to fermented feather powder,By using Pseudomonas sp.H8 to produce lipase,feather protein degradation rate was increased by Pseudomonas sp.W7.Through five factors of the experiment: fermentation temperature,fermentation time,inoculation ratio,bacteria quantity and shaking speed,the optimum conditions for the degradation of feather powder with Double strain is determined: The fermentation temperature are 30 ℃,the fermentation time was 9 days,the ratio of inoculation(Pseudomonas sp.W7: Pseudomonas sp.H8)was 2: 1,the bacteria quantity was 1%,and the shaking speed was 140 r·min-1.The hydrolysis rate of the two strains was 35.71%,which was 51.18% higher than that of Pseudomonas sp.W7 alone.The in vitro digestibility of the residue was 72.86%,which was 14.38% higher than that of Pseudomonas sp.W7 alone.The soluble protein and the content was 875 mg·L-1,which was 52.17% higher than that of Pseudomonas sp.W7.The apparent structure of feather powder before and after fermentation was observed by scanning electron microscopy(SEM),The undegraded feather powder showed dense fiber or lamellar structure;after Being degraded by Pseudomonas sp.W7,the feather powder fiber and lamellar structure were destroyed and changed into smooth polyhedron structure;after the Pseudomonas sp.H8 fermented part of the feather powder fiber and lamellar structure was destroyed,there are partially empty polyhedron structure;after the combination of double strains of feather powder fiber and lamellar structure are destroyed,A porous polyhedron structure appeared,which decreased its stability and led to the increasing digestiblity.and this structure makes its stability worse,resulting in increased digestibility.