响应面法优化羽毛降解菌Ochrobactrum intermedium JY-25的降解培养基

Optimization of the Degradation Medium of Feather-degrading Bacteria Ochrobactrum intermedium JY-25 by Response Surface Methodology

【目的】作为构成羽毛主要成分的角蛋白,因其存在大量相互交联的二硫键、氢键和盐键等化学键,导致羽毛结构稳定难以被常规手段降解。相较于物理、化学方法降解废弃羽毛,利用微生物产生的角蛋白酶使废弃羽毛变成可再生资源,具有高效、环保的优点。课题组前期从家禽养殖场的土壤中分离、筛选到一株羽毛降解菌,经鉴定该菌株为中间苍白杆菌JY-25。研究旨在进一步提高中间苍白杆菌JY-25的羽毛降解率,为今后工业化降解废弃羽毛提供依据。【方法】依次采用单因素试验、Plackett-Burman试验设计和响应面法对中间苍白杆菌JY-25的羽毛降解培养基进行优化。【结果】通过单因素试验确定了在降解培养基中外加碳源(糊化淀粉)和氮源(玉米粉)时,都能提高羽毛的降解率。Plackett-Burman试验设计发现降解培养基的8种成分中,糊化淀粉、硫酸亚铁和羽毛量是影响中间苍白杆菌JY-25对羽毛降解率的显著因素。最后通过响应面法确定了最佳降解培养基的组分为:羽毛2 g/L、糊化淀粉15 g/L、玉米粉10 g/L、硫酸亚铁0.02 g/L、磷酸氢二钾1.5 g/L、氯化钠0.3 g/L、硫酸镁0.025 g/L、氯化钙0.025 g/L,在该优化的培养基配方下,菌株JY-25的羽毛降解率高达76.31%,相较于初始的降解率提高了24.4%。【结论】经过多种优化方式,显著地提高了中间苍白杆菌JY-25的羽毛降解率,为菌株用于工业化降解废弃羽毛提供了理论基础。

[Objectives]Keratin,the main component of feathers,has a large number of cross-linked disulfide bonds,hydrogen bonds,and salt bonds among other chemical bonds,makes the feather structure stable and difficult to be degraded by conventional means.Compared with the degradation of waste feathers by physical and chemical methods,the use of keratinase produced by microorganisms to turn waste feathers into renewable resources has the advantages of high efficiency and environmental protection.The research team isolated and screened a feather-degrading bacterium from the soil of the poultry farm in the early stage,and the strain was identified as Ochrobactrum intermedium JY-25,which could be used to further improve the feather degradation rate of Ochrobactrum intermedium JY-25 to deal with waste feathers industrially in the future.[Methods]The single factor test,Plackett-Burman test designs and response surface methods were used to optimize the feather degradation medium of Ochrobactrum intermedium JY-25.[Results]Through single-factor experiments,it was determined that adding carbon sources(gelatinized starch)and nitrogen sources(corn meal)to the degradation medium could increase the degradation rates of feathers.The Plackett-Burman experimental designs found that among eight components of the degradation medium,gelatinized starch,ferrous sulfate and feather amount were significant factors affecting the degradation rates of Ochrobactrum intermedium JY-25 on feathers.Finally,the components of the optimal degradation medium were determined by response surface methodology:feather 2 g/L,gelatinized starch 15 g/L,corn flour 10 g/L,ferrous sulfate 0.02 g/L,dipotassium hydrogen phosphate 1.5 g/L,sodium chloride 0.3 g/L,magnesium sulfate 0.025 g/L,and calcium chloride 0.025 g/L.Under the optimized medium formula,the degradation rate of the strain JY-25 on feathers was as high as 76.31%,which increased by 24.4%compared with the initial degradation rate.[Conclusion]After a variety of optimization methods,the feather degradation rate of Ochrobactrum intermedium JY-25 had been significantly improved,providing a theoretical basis for the strain to be used for the industrial degradation of discarded feathers in the future.