Activity of some enzymes of a Pb-adapted strain of Rhizopus arrhizus augmented significantly during bioaccumulation of Pb from a chemically defined medium. The mycelium of a Pb-adapted strain exposed to 1 microg/mL Pb in a defined medium for 10 d at 28 +/- 2 degrees C exhibited, relative to a wild-type strain, increased activities of antioxidant enzymes, i.e. SOD, CAT and GPX and of enzymes like AP and PPO involved in defense against pathogens. Another response is a significant increase in the cellular thiol content after 4 d. The responses to Pb exposure thus include an increase in the antioxidant and anti-pathogen defense, and an increased metal-chelating ability.
- MeSH
- antifungální látky metabolismus MeSH
- enzymy metabolismus MeSH
- fungální léková rezistence MeSH
- fungální proteiny metabolismus MeSH
- kultivační média chemie MeSH
- mycelium enzymologie metabolismus účinky léků MeSH
- olovo metabolismus MeSH
- Rhizopus enzymologie metabolismus účinky léků MeSH
- sulfhydrylové sloučeniny metabolismus MeSH
The production of L(+)-lactic acid and formation of gamma-linolenic acid by 50 Rhizopus strains growing on saccharidic substrates were investigated. Formation of acids was observed on solid cultivation media but mainly during submerged fermentation. Strains with the highest selectivity of both L(+)-lactic acid production and gamma-linolenic acid formation were tested in a laboratory fermenter. The best producer was treated by UV irradiation to increase the fatty acid content in the biomass, especially that of gamma-linolenic acid. The conversion of 10% saccharidic substrate by this newly prepared strain Rhizopus arrhizus CCM 8109 results in more than 95% of theoretical yield of L(+)-lactic acid and permits a volume productivity of 0.4 g gamma-linolenic acid per liter.
