Yeast HXK2 gene reverts glucose regulation mutation of penicillin biosynthesis in P. chrysogenum

The mutant Penicillium chrysogenum strain dogR5, derived from strain AS-P-78, does not respond to glucose regulation of penicillin biosynthesis and β-galactosidase, and is partially deficient in D-glucose phosphorilating activity. We have transformed strain dogR5 with the (hexokinase) hxk2 gene from Saccharomyces cerevisiae. Transformants recovered glucose control of penicillin biosynthesis in different degrees, and acquired a hexokinase (fructose phosphorylating) activity absent in strains AS- P-78 and dogR5. Interestingly, they also recovered glucose regulation of β-galactosidase. On the other hand, glucokinase activity was affected in different ways in the transformants; one of which showed a lower activity than the parental dogR5, but normal glucose regulation of penicillin biosynthesis. Our results show that Penicillium chrysogenum AS-P-78 and dogR5 strains lack hexokinase, and suggest that an enzyme with glucokinase activity is involved in glucose regulation of penicillin biosynthesis and β-galactosidase, thus signaling glucose in both primary and secondary metabolism; however, catalytic and signaling activities seem to be independent.

Penicillin production by wild isolates of Penicillium chrysogenum in Pakistan

The present study was aimed at exploring the native wild isolates of Penicillium chrysogenum series in terms of their penicillin production potential. Apart from the standard medium, the efforts were made to utilize suitable agro-industrial wastes for the maximum yield of penicillin. Two series of P. chrysogenum were isolated from local sources and named as P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2. The native series were found to possess better penicillin production potential than the already reported series of P. chrysogenum. However, P. chrysogenum series UAF R1 was found to be the best candidate for high yield of penicillin starting at 100 hour as compared to P. chrysogenum series UAF R2 which produced the highest yield of penicillin at 150 hours for a shorter period of time. Addition of Corn Steep Liquor (CSL) to the fermentation medium resulted in the production of 1.20g/L penicillin by P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2. The fermentation medium in which Sugar Cane Bagasse (SCB) was replaced with CSL resulted in the highest yield of penicillin (1.92g/L) by both native series of P. chrysogenum. The penicillin production was increased by 62.5% in medium with SCB as compared to that with CSL. The penicillin yield of medium containing lactose and phenyl acetate was higher than that of control medium. Overall results revealed that P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2 may be recommended for better yield of natural penicillin and this efficiency may be further enhanced by utilizing SCB as substrate in the growth medium.

Screening and genetic improvement of pectinolytic fungi for degumming of textile fibers

Aiming at contributing to technological improvements in plant fiber processing methods, this paper reports research work on the obtainment of more efficient pectinase-producing fungi strains. More specifically, this work reports the analysis of 18 strains of filamentous fungi, with the purpose of obtaining enzymes for textile fibers degumming. The strains were evaluated for production of pectinolytic enzymes under several growth conditions (culture medium and growth temperature). Production of pectinases was measured by an enzymatic index (EI) in solid pectin medium. Among the tested strains, Penicillium chrysogenum IFO 4626 (Q 176) showed the best performance. Genetic improvement of this strain was carried out to increase its pectinase production, while keeping cellulase activity down to a negligible level, since cellulases are known to decrease the resistance of the fiber. Variability was induced through several cycles of mutation and selection by exposing conidea to ultra-violet light (UV). We selected 39 out of 390 isolated colonies. Resulting mutants produced nine times more pectin lyase (PL) than the original strain in terms of PL specific activity, and five times more in terms of PL activity (i.e. mmoles liberated per minute of reaction per mL of medium). Periodically, mutant performance was evaluated in solid pectin medium. Genetic stability was maintained for four years after isolation.

Com a intenção de melhorar tecnologicamente os métodos de processamento de fibras vegetais, o presente trabalho comunica pesquisas feitas para obter linhagens mais eficientes de fungos produtores de pectinases. Mais especificamente com o objetivo de obter enzimas para degomagem de fibras têxteis caracterizou-se 18 linhagens de fungos filamentosos quanto a algumas condições de cultivo (meio de cultura e temperatura de crescimento) e quanto ao índice enzimático (IE) em meio de pectina sólido. Constatou-se superioridade da linhagem IFO 4626 (Q 176) de Penicillium chrysogenum e conduziu-se melhoramento genético da mesma com o objetivo de elevar sua produção de pectinases, mantendo em níveis insignificantes a atividade de celulases. Induziu-se mutações por meio de luz ultra-violeta e selecionou-se as 39 melhores linhagens entre 390 isolados. Obteve-se mutantes com produção de pectina liase aproximadamente nove vezes superior à da linhagem original no que se refere à atividade específica de PL e cinco vezes superior em termos de atividade de PL (liberação de µMoles por minuto de reação e mL de meio). Periodicamente, o desempenho dos mutantes foi avaliado em meio de pectina sólido. A estabilidade genética manteve-se por 4 anos após o isolamento dos mesmos.