以魔芋多糖为碳源的产聚羟基丁酸酯菌的筛选、鉴定及发酵研究

Screening,identification and ferment conditions of polyhydroxybutyrate-producing bacteria with konjac glucomannan as carbon source

为充分利用发酵魔芋低聚糖所产生的菌体废弃物,降低微生物发酵法生产聚羟基丁酸酯(PHB)的成本,从云南省种植魔芋的土壤中分离得到一株以魔芋多糖为唯一碳源生长的菌株LKH,该菌可以分泌β-甘露聚糖酶水解魔芋多糖生长,并在胞内积累PHB。经形态学、生理生化特征及16S rDNA序列分析表明,菌株LKH归属于依利诺斯类芽孢杆菌。红外光谱和气相色谱分析结果显示,以魔芋多糖为碳源培养的细菌胞内提取的白色薄膜物质中含有PHB。当氮源(NH_4Cl)浓度为0.2g/L时,菌体以魔芋多糖为碳源合成的PHB质量最高可达0.85g/L,其含量达到69.55%,提取率为93.29%。

In order to make full use of the bacterial wastes from ferment broth of konjac oligosaccharides and reduce the production cost of polyhydroxybutyrates（PHB）by microbial fermentation,a strain named LKH is isolated from the soil for planting konjac in Yunnan Province,which can grow with konjac glucomannan as the sole carbon source.This bacterium is able to secreteβ-mannase to hydrolyze konjac glucomannan and simultaneously accumulate intracellular PHB.Strain LKH is identified as Paenibacillus illinoisensis according to its morphological,physiological and biochemical characteristics,and 16 SrDNA sequence analysis.The infrared spectra and gas chromatography show that the white film material extracted from Strain LKH cultured with konjac glucomannan as carbon source contains PHB.When the concentration of nitrogen source（NH4 Cl）is 0.2 g/L,the highest mass of PHB from Strain LKH cultured in konjac glucomannan is 0.85 g/L,and the content and extraction rate of PHB reach 69.55% and 93.29%,respectively.