利用PCR-DGGE技术分析微生态制剂在传代过程中的菌群变化

利用变性梯度凝胶电泳（denaturing gradient gel electrophoresis, DGGE）技术，结合传统平板培养法对实验室研制的1种由乳酸菌和芽孢杆菌组成的微生态菌剂WS-401及其在连续转接培养过程中细菌种群组成的动态变化进行分析。WS-401原液的活菌数为2×107 cfu/mL，且细胞个体形态多样。将分离自原液的3株细菌进行DGGE分析，出现2种指纹谱带，对照标准的DGGE指纹图谱库和序列分析，分别被鉴定为蜡状芽孢杆菌（Bacillus cereus）和嗜热链球菌（Streptococcus thermophilus）。将该菌剂分别在LB和MRS两种培养基中30℃或37℃连续转接5次，DGGE分析每次转接后培养物的菌群组成，结果发现，随着转接次数的增加，微生物菌群的种类减少，在LB培养基中转接5次后优势菌群只有蜡状芽胞杆菌，而在MRS培养基中转接后优势菌群为植物乳杆菌（Lactobacillus plantarum）和类干酪乳杆菌（Lactobacillus paracasei）。由此说明，微生物的营养基质和培养条件对微生态制剂在传代过程中的菌群组成和动态变化有重要影响。

Application of PCR-DGGE technique to monitor the species changes of microecological preparation after successive cultures

Denaturing gradient gel electrophoresis (DGGE) technique combined with classical plate culture and sequencing of partial 16S ribosomal RNA (rRNA) genes were applied to examine microbial community changes of microecological preparation, which was coded as WS-401, composed of lactic acid bacteria and Bacillus sp., and subjected to successive sub-cultured processes. The population of bacteria with a diverse morphology in WS-401 preparation was 2×107cfu/mL. Two types of band patterns appeared on DGGE gel for three strains of isolates, implying two different species. These isolates were identified as Bacillus cereus and Streptococcus thermophillus by comparison with identification ladder and sequence analysis. When the microecological preparation WS-401 was continuously sub-culturing for five times in medium LB and MRS medium and at 37℃ or 30℃, respectively, microbial communities largely changed. The results show that Bacillus cereus is dominant in LB medium, while L. plantarum and L. paracasei are dominant in MRS medium. It was concluded that medium components and culture conditions have significant influences on microbial communities and species dynamic changes of microecological preparation.