Effect of Vitreoscilla hemoglobin on production of a chemotherapeutic enzyme, L‐asparaginase, by Pseudomonas aeruginosa

Abstract

The production of L-asparaginase, an enzyme widely used in cancer chemotherapy, is mainly regulated by carbon catabolite repression and oxygen. This study was carried out to understand how different carbon sources and Vitreoscilla hemoglobin (VHb) affect the production of this enzyme in Pseudomonas aeruginosa and its VHb-expressing recombinant strain (PaJC). Both strains grown with various carbon sources showed a distinct profile of the enzyme activity. Compared to no carbohydrate supplemented medium, glucose caused a slight repression of L-asparaginase in P. aeruginosa, while it stimulated it in the PaJC strain. Glucose, regarded as one of the inhibitory sugars for the production L-asparaginase by other bacteria, was determined to be the favorite carbon source compared to lactose, glycerol and mannitol. Furthermore, contrary to common knowledge of oxygen repression of L-asparaginase in other bacteria, oxygen uptake provided by VHb was determined to even stimulate the L-asparaginase synthesis by P. aeruginosa. This study, for the first time, shows that in P. aeruginosa utilizing a recombinant oxygen uptake system, VHb, L-asparaginase synthesis is stimulated by glucose and other carbohydrate sources compared to the host strain. It is concluded that carbon catabolite and oxygen repression of L-asparaginase in fermentative bacteria is not the case for a respiratory non-fermentative bacterium like P. aeruginosa.

Optimization and Purifi cation of L-Asparaginase Produced by Streptomyces tendae TK-VL_333

“…The pH value of media amended with other carbon sources was in the acidic region which may be the reason for low productivity of L-asparaginase; this is evident from reports stating that acidity of the fermentation medium could inhibit the production of L-asparaginase (Geckil et al, 2006;Narayana et al, 2008).…”

L-asparaginase production by Streptomyces albidoflavus

“…The acidic nature of fermentation medium could inhibit asparaginase biosynthesis. Glucose is reported to be a repressor of asparaginase synthesis due to the acid production [12].…”

Overexpression of type I L-asparaginase ofBacillus subtilis inEscherichia coli, rapid purification and characterisation of recombinant type I L-asparaginase

“…The type II enzyme with the high affinity markedly inhibited lymphomas in mice, whereas the type I enzyme with the low affinity was ineffective (Schwarts et al, 1966). Their properties have been studied in Escherichia coli (Bagert and Röhm, 1989;Harms et al, 1991aHarms et al, , 1991b, Erwinia carotovora (Kotzia and Labrou, 2005), Erwinia chrythanthemi (Aghaiypour et al, 2001), Pseudomonas aeruginosa (Geckil et al, 2006), Saccharomyces cerevisiae (Kim et al, 1988), and Pyrococcus horikoshii (Yao et al, 2005). Especially, the type II enzymes of Escherichia coli and Erwinia chrysanthemi have been intensively investigated with respect to their antitumor activity.…”