嗜酸菌硫桿菌突變株之篩選與生理活性研究

Abstract

本實驗室先前利用自營性嗜酸性硫桿菌去處理沼氣中的硫化氫，結合化學反應之高氧化性及生物反應之再生循環，以提高沼氣發電可行性。自營性嗜酸性硫桿菌(Acidithiobacillus sp. CP1)為化學自營菌，生長速度非常緩慢，使整個系統效率受限於生物反應，因此希望能藉由突變而得到可快速氧化二價鐵之菌株，提昇硫化氫去除效率而得到更高純度之甲烷，作為有效能源加以利用。 本實驗利用NTG(N-methyl-N’-nitro-N-nitrosoguanidine)與Acidithiobacillus sp. CP1 作用後，篩選出具高氧化二價鐵能力之突變株Acidithiobacillus sp. A47-1，並找出其最佳化之生長條件(二價鐵離子濃度20 g L-1，通氣量1600 ml min-1，擔體大小 4.75mm )，在硫化氫濃度為2000 ppm 、鐵離子濃度為20g L-1條件下，野生株之最大硫化氫去除率為14 g L-1hr-1，突變株A47-1之硫化氫去除率最高可為152.5 g L-1hr-1為野生株之11倍，且效率達99%以上，此次突變所得之突變株A47-1，大幅提升生物槽鐵再生之能力，並間接提高硫化氫去除系統處理效能。

Utilization of biological-chemical H2S gas removal system can purify marsh gas efficiently. The combined system contains rapid H2S oxidation in chemical reactor and Fe3+ regeneration in biological reactor to purify methane. The microbial strain we used originally was Acidithiobacillus sp. CP1 which is a chemolithotrophic bacteria, ferric iron regeneration efficiency was limited due to slow bacteria grow rate. The maximal H2S removal capacity in the original system was only 14g L-1 hr-1. In this study, NTG(N-methyl-N’-nitro-N-nitrosoguanidine) was applied to wild type strain Acidithiobacillus sp. CP1 for random mutation. All the formative colonies were picked up and screened to obtain the highest oxidation ability and was named mutant strain Acidithiobacillus sp. A47-1. Futher studies were conducted to reveal the optimal growth condition of mutant strain Acidithiobacillus sp. A47-1(Fe2+ concentration is 20 g L-1；air flux rate is 1600 ml mim-1；carrier size is 4.75mm). The mutant strain Acidithiobacillus sp. A47-1 was examined in the biological-chemical combined system in the condition that the H2S gas and iron concentration were 2000ppm and 20g L-1, respectively. The maximal H2S removal capacity of the system was 152.4g L-1 hr-1, which was 11 folds higher than the wild type Acidithiobacillus sp. CP1. In addition, the removal efficiency was 99%. Therefore, we elevated the H2S removal capacity and efficiency via improvement of Fe3+ regeneration ability of mutant strain Acidithiobacillus sp. A47-1.