Degradation of chlorobenzoates byAspergillus niger

Utilization of aromatic compounds by the Penicillium strain Bi 7/2

The Penicillium strain Bi 7/2 utilized phenol, catechol, resorcinol, hydroquinone, pyrogallol, hydroxyhydroquinone, phloroglucinol, m- and p-cresol, orcinol, 4-methylcatechol, 4-methoxyphenol, 4-aminophenol, benzyl alcohol, benzoic acid, 2-, 3- and 4-hydroxybenzoic acid, anthranilic acid, protocatechuic acid and gallic acid as sole sources of carbon and energy. The central metabolites catechol, protocatechuic acid and hydroxyquinone could be determined by HPLC with diode-array detection. Pathways for the degradation of aromatic substances were proposed.

Degradation of 2-bromobenzoic acid by a strain of Pseudomonas aeruginosa

A strain of Pseudomonas aeruginosa producing 2-bromobenzoic acid, designated 2-BBZA, was isolated by enrichment culture from municipal sewage. It degraded all four 2-halobenzoates as well as certain 3-halo- and dihalobenzoates, though none of the 4-halobenzoates supported growth of this organism. 3-Hydroxybenzoate and 3-chlorocatechol were respective inhibitors of salicylate and catechol oxidation: when each was added separately to resting cells incubated with 2-bromobenzoate, salicylate and catechol were found. Oxygen uptake data suggest that the same dehalogenase may be involved in the oxidation of 2-bromo-, 2-chloro-, and 2-iodobenzoates.

Role of cAMP in the mediation of glucose catabolite repression of glucoamylase synthesis in Aspergillus awamori

Exogenous cAMP was shown to mimic glucose in its effect on the synthesis of glucoamylase in Aspergillus awamori. cAMP (4 mM) when added to the starch medium blocked the derepression of glucoamylase by inhibiting its protein synthesis by about twofold. The repressive effect of cAMP on the glucoamylase synthesis was found to be due to twofold reduction in the glucoamylase specific mRNA levels. This cAMP related repression of the glucoamylase mRNA levels was most likely brought about at the level of gene transcription as cAMP had no apparent effect on the processing or stability of glucoamylase mRNA.

Transformation of Aspergillus niger using the homologous orotidine-5'-phosphate-decarboxylase gene

A homologous transformation system for the filamentous fungus Aspergillus niger has been developed, based on the orotidine-5'-phosphate-decarboxylase gene. A. niger Pyr- mutants have been selected from 5-fluoro-orotic acid resistant mutants. These mutants were found to comprise two complementation groups, pyrA and pyrB. The A. niger OMP-decarboxylase gene was isolated from a gene library by heterologous hybridization with the Neurospora crassa pyr4 gene. The cloned gene is capable to transform A. nidulans pyrG mutants at high frequencies. Transformation of A. niger pyrA mutants occurs with moderate frequencies (about 50 transformants/micrograms DNA) whereas the pyrB mutants cannot be complemented with the cloned OMP-decarboxylase gene. Analysis of the DNA of the A. niger PyrA+ transformants showed that transformation resulted in integration of the vector DNA into the genome by homologous recombination. Both gene replacements and integration of one or more copies of the complete vector have been observed.