Isolation and characterization of selenate resistant mutants of Acremonium chrysogenum

• Autor(a) principal: Vialta,Airton
• Data de Publicação: 1999
• Outros Autores: Catani,Cleide F, B. Junior,Renato, Azevedo,João L
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Archives of Biology and Technology
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89131999000300016
• topic: Selenate resistant mutant; Acremonium chrysogenum; cephalosporin C

Mutants unable to convert exogenous sulfate to sulfite were isolated using the toxic analogue selenate. Three of twenty-eight isolated mutants were chromate sensitive. They showed a possible lesion in the gene that codes the ATP sulfurylase. The others were chromate resistant, and probably had a lesion in one or both of the genes that code the sulfate permease. Methionine increased the resistance levels to selenate. In addition, the frequency of spontaneous mutants obtained in a medium containing methionine was higher (between 2.4 x 10-6 and 18.0 x 10-6) than that obtained using a medium without any intentional source of sulfur (between 0.7 x 10-6 and 5.0 x 10-6). The original strain, as well as the mutants, were able to grow in a sulfur-free liquid medium even after 4 consecutive inoculation procedures. These results indicated the existence of sulfur traces in the medium and/or an efficient intracellular storage system. There was no significant difference between cephalosporin C production in mutants and the original strain.