- 學位論文
利用固態發酵生產不同芽孢桿菌菌株
Solid-state fermentation of various Bacillus species
摘要
現今畜牧業大量使用抗生素來增加牲畜的飼料產肉效力及降低飼養成本，抗生素的濫用已經造成環境與水的污染，濫用抗生素會造成環境中細菌或病毒產生抗藥性，這對人類的醫療與健康是一個大威脅，如何尋找其他替代的方法以降低抗生素的使用，已經成為畜牧業必須面對的課題。益生菌的餵食是已知可以替代抗生素的方法，其中又以芽孢桿菌屬(Bacillus)最受矚目。本實驗之目的在探討Bacillus licheniformis、B. subtilis、B. subtilis var. natto 以不同的農業副產物配合適當微生物培養基進行固態發酵，從實驗室研發規模，進而擴大化生產含高濃度芽孢桿菌孢子的動物飼料。本實驗結果發現：B. licheniformis、B. subtilis、B. subtilis var. natto 以稻殼與大豆粉2：1的比例最適合芽孢桿菌生長，原料殺菌3小時可以殺死雜菌的耐熱性孢子，微生物培養基中葡萄糖與其他原料需分開殺菌，可以避免產生梅納反應，以免抑制芽孢桿菌生長，改良的固態發酵可在培養3天後使菌數高達10的10次方CFU/g。
並列摘要
Nowadays, antibiotics are widely used in livestock for increasing feed conversion efficacy and reducing costs. However, abuses of antibiotics have caused water and environment pollutions, as well as development of drug resistant pathogens, which become a major threat of human health. Researching alternative methods to reduce the use of antibiotics has become an important task or challenge in animal husbandry. Using probiotics to replace antibiotics in feeds is one of fensible strategies. People have drawn a great attention to the use of Bacillus spp. in animal feed. The present study investigated solid-state fermentation of Bacillus licheniformis, B. subtilis and B. subtilis var. natto using different agricultural by-products as fermentation substrates to make high cell density products as animal feed supplements. The investigation was initially studied on a lab scale and later was scaled up to a pilot production. The experimental results showed that rice husk to soybean meal on 2:1 ratio is suitable for use as medium formulation for cultivation of B. licheniformis, B. subtilis and B. subtilis var. natto. Sterilization time of 3 hours was required to kill all the heat resistant spores in the fermentation substrates. Additionally, glucose has to be sterilized separately from other ingredients in order to avoid Mallard reaction, which was found to inhibit the growth of Bacilli in this study. The optimized medium formulation and solid state fermentation process can produce fermentation products containing bacteria spores up to 10 to the power of 10 CFU/g after 3 days fermentation, which is satisfactory for the commercial production purpose.