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Fungal cellulolytic and hemicellulolytic enzymes are promising tools for industrial hydrolysis of cellulosic biomass; however, the regulatory network underlying their production is not well understood. The recent discovery of the transcriptional activators ClrB and McmA in Aspergillus nidulans implied a novel regulatory mechanism driven by their interaction, experimental evidence for which was obtained from transcriptional and DNA-binding analyses in this study. It was found that ClrB was essential for induced expression of all the genes examined in this study, while McmA dependency of their expression was gene-dependent. DNA-binding studies revealed McmA assisted in the recruitment of ClrB to the cellulose-responsive element (CeRE) in the promoters of eglA and eglB, expression of which was significantly reduced in the mcmA mutant. The CCG triplet within the CeRE served as the recognition sequence for the ClrB monomer. In contrast, ClrB did not require McmA for binding as a homodimer to the CGGN8CCG sequences in the promoter of mndB, expression of which was affected less in the mcmA mutant than in all other examined genes. Thus, there are two types of ClrB-mediated regulation: McmA-assisted and McmA-independent. This novel McmA–ClrB synergistic system provides new insights into the complex regulatory network involved in cellulase and hemicellulase production.

Transformation of carbon tetrachloride (CT) and tetrachloroethylene (PCE) was studied under methanogenic conditions, in the presence or absence of toluene, ethylbenzene, phenol, and benzoate. Microbial inocula for the experiments were derived from three groundwater aquifers contaminated by jet fuel or creosote. CT and PCE were reductively dechlorinated in all the examined cases (CT to chloroform [CF]; PCE to trichloroethylene [TCE], trans-l,2-dichloroethylene [DCE], and vinyl chloride [VC]). In the aquifer microcosms, the electron donors used for the reductive transformations were most likely the unidentified organic compounds present on aquifer solids, or storage materials in microorganisms. Alternatively, molecular hydrogen from the anaerobic incubator atmosphere could have been used. The addition of benzoate caused a decrease in rates of dechlorination if benzoate was transformed. Phenol and ethylbenzene were not degraded and did not influence the transformation of CT or PCE. Toluene, in most of the studied cases, had no influence on reductive dechlorination of either CT or PCE. Only in microcosms derived from a JP-4 jet fuel-contaminated aquifer did the anaerobic degradation of toluene occur simultaneously with reductive dechlorination of PCE, suggesting that toluene might possibly have been used as an electron donor for reductive transformation of chlorinated solvents.