第58屆Intel ISEF中國參賽項(xiàng)目：對羽毛降解菌株的篩選及菌體最佳生長條件的實(shí)驗(yàn)探究
吉林省實(shí)驗(yàn)中學(xué) 高三 李昂
學(xué)科：微生物學(xué)
本研究針對羽毛角質(zhì)蛋白難以降解，造成巨大浪費(fèi)這一現(xiàn)狀。從自然界腐敗羽毛中篩選出了能夠有效降解角質(zhì)蛋白的微生物菌株。探索出有效的篩選分離培養(yǎng)基和篩選菌株的方法。選擇對菌株生長繁殖影響較大的因素進(jìn)行了：培養(yǎng)基成分配比實(shí)驗(yàn)、培養(yǎng)基pH值實(shí)驗(yàn)、水分活度值實(shí)驗(yàn)、培養(yǎng)溫度實(shí)驗(yàn)、培養(yǎng)時(shí)間實(shí)驗(yàn)等五個(gè)實(shí)驗(yàn)，找到了該菌株最佳生長條件為：蔗糖最佳加入量為羽毛粉質(zhì)量的2%左右；最佳pH值7.5～8.0；水分活度值在0.95左右比較合適；最佳培養(yǎng)溫度37℃±1℃；最佳培養(yǎng)時(shí)間48～52h。動物飼喂對比試驗(yàn)表明：經(jīng)該菌株降解的角質(zhì)蛋白比現(xiàn)有高溫水解角質(zhì)蛋白，動物消化率提高了34%，肉雞增重比對照組提高了近20%，為生產(chǎn)羽毛蛋白飼料提供參考數(shù)據(jù)和優(yōu)良菌株。
The Study of Screening of the Feather Degradation Strain and Its Best Culture Conditions
Microbiology
Li Ang 18, Jilin Provincial Experimental School
The objective of this study was to solve the existing problem that the feather keratin is difficult to degrade, which has resulted in a big waste of protein and environmental pollution. Microbial strains that can effectively degrade the feather keratin were screened from the feather that decayed in nature. Effective isolation media and methods of screening were found out. Factors that have a larger effect on the growth and enzyme production of the strain were selected to conduct five experiments on proportioning of culture media composition, pH of culture media, water activity, culture temperature and duration. Through mensurating the numbers of thallus, nitrogen content and optical density in the degradation solution, the optimum culture conditions for the strain were found out from the experiments: cane sugar is the better carbon sources of this strains and the optimum amount of cane sugar added was approximately 2% of the weight of the feather powder, the optimum pH 7.5-8.0, the more appropriate water activity approximately 0.95, the optimum culture temperature 37℃±1℃ and the optimum culture duration 72h. The simulated experiments of the rate of pepsin digestion in animals showed that the rate of digestion in animals has reached to 70.26% after the feather keratin is degraded by the strain, and the rate of digestion in animals is increased by 34% compared with the high temperature hydrolyzed keratin now available, providing reference data and excellent strains for the production of feather protein feed.
