病死猪尸体降解复合菌的筛选、鉴定、优化及应用效果评价

Screening,identification,optimization,and application evaluation of compound bacteria for degradation of diseased pig carcasses

摘要:

【背景】我国生猪病死率较高，建立高效的病死猪尸体无害化处理方式尤为重要。【目的】提高病死猪尸体堆肥无害化处理效率。【方法】筛选具有蛋白质和脂肪降解功能的菌株，并构建复合菌剂，利用单因素和响应面方法对其菌种配比及降解条件进行优化，对其接种于病死猪和锯末堆肥进行应用效果评价。【结果】经鉴定，菌株DB1为粘质沙雷氏菌，所产蛋白酶活力为36.76 U/mL，猪肉降解率为72.17%。菌株ZF2为贝莱斯芽孢杆菌，所产脂肪酶活力为12.33 U/mL，猪肉降解率为70.83%。复合菌剂中DB1与ZF2最佳菌种配比为2.55:1，响应面优化其最佳降解条件为温度31.65 ℃、接种量3.11%、pH 6.0、盐度0.75%、Mn²⁺浓度1 mmol/L。在此条件下进行猪肉降解实验，7 d后降解率达90.61%。堆肥实验显示对照组和低、中、高接种量组堆肥峰值温度分别可达60、64、69和62 ℃。其中3%接种量的处理效果最佳，高温期可维持19 d，病死猪降解率达98.06%，各指标均极显著优于对照组(p<0.01)。【结论】首次根据生猪中肥瘦比设计猪肉降解实验来评价功能菌的作用效果，较前人方法有所改进。以猪肉降解率作为评价指标，优化了功能菌的菌种配比，与前人研究相比具有更好地加速堆肥升温和加快病死猪尸体降解的能力。

关键词:病死猪降解菌;复合菌剂;菌种配比;堆肥

Abstract:

[Background] In view of the high mortality of live pigs due to diseases in China,it is particularly important to establish an efficient harmless method for treating diseased pig carcasses.[Objective] In order to improve the harmless treatment efficiency of compost on diseased pig carcasses.[Methods] We screened out the strains with protein and fat degradation functions and formulated the compound bacterial agents.Single factor experiments and response surface method were employed to optimize the strain ratio and degradation conditions.The degradation performance of compound bacterial agents on diseased pig carcasses and sawdust compost were evaluated.[Results] Strain DB1 was identified as Serratia marcescens with a protease activity of 36.76 U/mL and a degradation rate of 72.17% for pig carcass.Strain ZF2 was Bacillus velezensis,with a lipase activity of 12.33 U/mL and a degradation rate of 70.83% for pig carcass.The optimal ratio of DB1 to ZF2 in compound bacterial agent was 2.55:1,and the optimal degradation conditions obtained by response surface optimization were as follows:temperature at 31.65℃,inoculation amount of 3.11%,pH 6.0,salinity of 0.75%,and Mn²⁺ concentration of 1 mmol/L.A degradation test was carried out under the optimum conditions,which showed a degradation rate of 90.61% after 7 days.The composting test showed that the peak temperature of compost in the control group and the low-,medium-,and high-amount inoculation groups could reach 60,64,69,and 62℃,respectively.The group with an inoculation amount of 3% had the best treatment performance,with the high temperature period lasting for 19 days and the carcass degradation rate of 98.06%.All the indicators of this group were superior to those of the control group (p<0.01).[Conclusion] In this study,we designed the degradation test according to the fat/lean ratio of pig carcass for the first time to evaluate the performance of functional bacteria,which was superior to the previous methods.Taking the degradation rate as the evaluation index,we optimized the strain ratio of functional bacteria.Compared with those in previous studies,the compound bacterial agent designed in this study can well accelerate the temperature rise of composting and the degradation of pig carcass.

Key words:diseased pig carcass-degrading bacteria;compound bacterial agent;strain ratio;compost