Mountfort D O, Asher R A
Appl Environ Microbiol. 1983 Dec;46(6):1331-8. doi: 10.1128/aem.46.6.1331-1338.1983.
Neocallimastix frontalis PN-1 utilized the soluble sugars D-glucose, D-cellobiose, D-fructose, maltose, sucrose, and D-xylose for growth. L-Arabinose, D-galactose, D-mannose, and D-xylitol did not support growth of the fungus. Paired substrate test systems were used to determine whether any two sugars were utilized simultaneously or sequentially. Of the paired monosaccharides tested, glucose was found to be preferentially utilized compared with fructose and xylose. The disaccharides cellobiose and sucrose were preferentially utilized compared with fructose and glucose, respectively, an cellobiose was also the preferred substrate compared with xylose. Xylose was the preferred substrate compared with maltose. In further incubations, the fungus was grown on the substrate utilized last in the two-substrate tests. After moderate growth was attained, the preferred substrate was added to the culture medium. Inhibition of nonpreferred substrate utilization by the addition of the preferred substrate was taken as evidence of catabolite regulation. For the various combinations of substrates tested, fructose and xylose utilization was found to be inhibited in the presence of glucose, indicating that catabolite regulation was involved. No clear-cut inhibition was observed with any of the other substrate combinations tested. The significance of these findings in relation to rumen microbial interactions and competitions is discussed.
额叶新美鞭菌PN-1利用可溶性糖D-葡萄糖、D-纤维二糖、D-果糖、麦芽糖、蔗糖和D-木糖进行生长。L-阿拉伯糖、D-半乳糖、D-甘露糖和D-木糖醇不能支持该真菌生长。使用成对底物测试系统来确定任意两种糖是同时还是依次被利用。在所测试的成对单糖中，发现葡萄糖与果糖和木糖相比优先被利用。纤维二糖和蔗糖这两种二糖分别与果糖和葡萄糖相比优先被利用，并且纤维二糖与木糖相比也是首选底物。木糖与麦芽糖相比是首选底物。在进一步的培养中，真菌在双底物测试中最后使用的底物上生长。在达到适度生长后，将首选底物添加到培养基中。添加首选底物对非首选底物利用的抑制被视为分解代谢调节的证据。对于所测试的各种底物组合，发现在葡萄糖存在下果糖和木糖的利用受到抑制，表明涉及分解代谢调节。在所测试的任何其他底物组合中均未观察到明确的抑制作用。讨论了这些发现与瘤胃微生物相互作用和竞争的关系。
