利用纤维二糖差向异构酶制备乳果糖的研究进展

乳果糖是由D-半乳糖和D-果糖两个基团通过β-1,4糖苷键连接而成的还原型二糖;乳果糖口服液具有治疗慢性便秘和肝性脑病的功效,在100多个国家作为常见非处方药(OTC)使用,需求量十分巨大;乳果糖还可以作为益生元改善人体肠道菌群关系。乳果糖的生产依赖化学法,其催化剂对人体有害,下游分离难度大。近年来,纤维二糖差向异构酶被发现能够高效催化乳糖制备乳果糖,该技术绿色环保、步骤简单,具有很强的产业化前景。本文结合自身研究经历对纤维二糖差向异构酶的研发情况进行总结,并综述了乳果糖酶法制备技术的现状。

Advances in bio-production of lactulose using cellobiose 2-epimerases

In order to screen the biocontrol bacteria with antagonistic effects on Rhizoctonia solani, bacterial strains were isolated from the rice samples infected by R. solani AG-1A from Jilin Province by using the method of dilution coated plate. The classification was established by gyrB gene sequence analysis; the biocontrol effect on rice sheath blight disease was determined based on in vitro infection and greenhouse experiments, and the mycelium growth on the rice pretreated with the strains was observed under microscope for analyzing the biocontrol mechanism. The results showed that 35 strains were isolated from the infected samples, and the strain ND11 showed the greatest bacteriostatic rate and diameter of bacteriostatic zone (74.12% and 31.50 mm, respectively). Strain ND11 was identified as Bacillus pumilus, which could slow down the infection rate of R. solani and inhibit the formation of R. solani AG-1A infection cushion. It had a significant antagonistic effect against rice sheath blight in the greenhouse experiment, with a biocontrol efficacy of up to 70.69%. The results indicated that the strain ND11 has a good control effect against rice sheath blight by inhibiting the formation of R. solani infection cushion, suggesting that the strain had the potential to be developed as a biocontrol agent.