The lexA-imuB-dnaE2 gene cassette contributing to the TLS (translesion synthesis) polymerase activity and can easily cause mutation after DNA damage in many bacteria. But it was previously thought that TLS polymerase activity was unlikely to exist in the radio-resistant genus Deinococcus. In our preliminary studies, the lexA-imuB-dnaE2 gene cassette was found in a newly isolated feather-degrading Deinococcus ficus. Here we have attempted to determine the imuB gene sequence from another Deinococcus species namely D. grandis, by using the newly designed primers. The destroying of either imuB or dnaE2 gene in D. ficus leads to the increase in UV sensitivity and decrease in UV-induced mutations, which demonstrated the existence of TLS polymerase activity in D. ficus. In the presence of lexA-imuB-dnaE2, it is possible to obtain mutants with various keratinolytic activities after UV exposure. The keratinolytic activity of mutant strain CC-ZG207 increased by approximately twofold during growth in liquid feather medium. In contrast, the mutant strain CC-ZG227 showed only half of the keratinolytic activity compared with the wild type strain. By utilizing SDS-PAGE and zymogram profile analysis, the change in the protease activity was observed. We have proposed that the superior mutants of D. ficus can be created under UV stress, which is mediated by the lexA-imuB-dnaE2 gene cassette.

-The objective of this work was to assess the productivity and polysaccharide-protein complex content of Agaricus blazei on rice straw medium, in comparison to conventional sawdust, using four casing soils. The A. blazei strain used was BCRC36814 T , purchased from the Food Industry Research and Development Institute, Hsin-Chu, Taiwan. The two media were evaluated as to A. blazei productivity, harvesting time, and production costs. The experimental design used was a randomized complete block, with four replicates.

A naphthalene-degrading isolate able to utilize naphthalene as a sole carbon source was identified as Gordonia sp. CC-NAPH129-6. Here a detail characterization of the naphthalene catabolic genes present in this strain was conducted. In nar region four structural genes (narAa, narAb, narB, narC), two regulatory genes (narR1, narR2), a rubredoxin encoding gene (rub1) and a gene (orf7) with unknown function were obtained. When compared with most of the members within naphthalene-degrading Rhodococcus, these naphthalene catabolic genes in strain CC-NAPH129-6 were organized into an operon-like gene cluster and present in the same order. This naphthalene gene cluster located in a 97-kb small plasmid of strain CC-NAPH129-6, as can be seen from the PFGE and Southern blot hybridization data. Besides, a partial transposase sequence containing an IS element structure with 12-nt inverted repeat at both ends was found, which was flanked by direct repeats downstream the narC gene in strain CC-NAPH129-6. This novel transposase gene sequence was unlike to the transposase sequence found between narR2 and rub1 genes in Rhodococcus opacus R7. The comparative analyses of the naphthalene catabolic genes, 16S rRNA and gyrB gene present in strain CC-NAPH129-6 and naphthalene-degrading Rhodococcus species imply that the naphthalene catabolic genes in strain CC-NAPH129-6 might be horizontally transferred from Rhodococcus members. This is the first report demonstrating that naphthalene catabolic genes organized into an operon-like gene cluster in the genus Gordonia, and this might provide evidence of the importance of this actinobacterial lineage in the bioremediation of oil-contaminated soils.

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