Pasti M B, Pometto A L, Nuti M P, Crawford D L
Department of Bacteriology and Biochemistry, University of Idaho, Moscow 83843.
Appl Environ Microbiol. 1990 Jul;56(7):2213-8. doi: 10.1128/aem.56.7.2213-2218.1990.
The lignocellulose-degrading abilities of 11 novel actinomycete strains isolated from termite gut were determined and compared with that of the well-characterized actinomycete, Streptomyces viridosporus T7A. Lignocellulose bioconversion was followed by (i) monitoring the degradation of [14C]lignin- and [14C]cellulose-labeled phloem of Abies concolor to 14CO2 and 14C-labeled water-soluble products, (ii) determining lignocellulose, lignin, and carbohydrate losses resulting from growth on a lignocellulose substrate prepared from corn stalks (Zea mays), and (iii) quantifying production of a water-soluble lignin degradation intermediate (acid-precipitable polymeric lignin). The actinomycetes were all Streptomyces strains and could be placed into three groups, including a group of five strains that appear superior to S. viridosporus T7A in lignocellulose-degrading ability, three strains of approximately equal ability, and three strains of lesser ability. Strain A2 was clearly the superior and most effective lignocellulose decomposer of those tested. Of the assays used, total lignocellulose weight loss was most useful in determining overall bioconversion ability but not in identifying the best lignin-solubilizing strains. A screening procedure based on 14CO2 evolution from [14C-lignin]lignocellulose combined with measurement of acid-precipitable polymeric lignin yield was the most effective in identifying lignin-solubilizing strains. For the termite gut strains, the pH of the medium showed no increase after 3 weeks of growth on lignocellulose. This is markedly different from the pattern observed with S. viridosporus T7A, which raises the medium pH considerably. Production of extracellular peroxidases by the 11 strains and S. viridosporus T7A was followed for 5 days in liquid cultures.(ABSTRACT TRUNCATED AT 250 WORDS)
测定了从白蚁肠道中分离出的11株新型放线菌菌株的木质纤维素降解能力，并与特征明确的放线菌绿产色链霉菌T7A进行了比较。木质纤维素生物转化通过以下方式进行：（i）监测[¹⁴C]木质素和[¹⁴C]纤维素标记的白云杉韧皮部降解为¹⁴CO₂和¹⁴C标记的水溶性产物；（ii）测定在由玉米秸秆（玉米）制备的木质纤维素底物上生长导致的木质纤维素、木质素和碳水化合物损失；（iii）定量水溶性木质素降解中间体（酸沉淀聚合物木质素）的产生。这些放线菌均为链霉菌菌株，可分为三组，包括一组五株在木质纤维素降解能力上优于绿产色链霉菌T7A的菌株、三株能力大致相当的菌株和三株能力较弱的菌株。菌株A2显然是所测试菌株中最优异、最有效的木质纤维素分解菌。在所使用的测定方法中，总木质纤维素重量损失在确定总体生物转化能力方面最有用，但在鉴定最佳木质素溶解菌株方面并非如此。基于从[¹⁴C-木质素]木质纤维素中释放¹⁴CO₂并结合测定酸沉淀聚合物木质素产量的筛选程序在鉴定木质素溶解菌株方面最为有效。对于白蚁肠道菌株，在木质纤维素上生长3周后，培养基的pH值没有升高。这与绿产色链霉菌T7A观察到的模式明显不同，后者会使培养基pH值大幅升高。在液体培养中对11株菌株和绿产色链霉菌T7A的细胞外过氧化物酶产生情况进行了为期5天的跟踪监测。（摘要截短为250字）
