Screening of thermotolerant yeasts as producers of superoxide dismutase

Abstract

A screening procedure for highly thermostable yeast superoxide dismutase was developed. Growth yields at various temperatures were estimated for ten mesophilic and thermotolerant strains, belonging to the genera Saccharomyces, Kluyveromyces and Pichia. Higher yields at 45°C were obtained for K. lactis 90‐3 and 90‐4. A correlation between the ability to grow at higher temperature and the thermostability of the superoxide dismutase enzyme synthesized was observed. A comparison of the operational stability of the superoxide dismutase of all tested strains suggests that the enzyme of K. lactis strains was more thermostable than that of the other tested microorganisms.

Purification and partial characterization of Cu/Zn superoxide dismutase from Kluyveromyces marxianus yeast

“…This strain-producer has been chosen due to its thermotolerance, high growth yield (Y x/c = 0.41) and maximal growth rate ( max = 0.35 h −1 ) and potentially valuable properties for producing Cu/Zn SOD with increased thermostability. It exhibits an increased operation temperature expressed in terms of half-life (t 1/2 ): 22 min at 75 • C [18].…”

“…The strain-specific Cu/Zn SOD thermostability [18] allows the performance of a rapid and efficient first step of the purification scheme, i.e. the thermotreatment of the cell-free extract.…”

“…During the cultivation process the following parameters were maintained: t • -38 • C; pO 2 -30%, aeration L L −1 min −1 ; agitation -300 rpm. The strain was cultivated on Rider nutrient medium [18] with lactose as a sole carbon source. The superoxide dismutase-enriched biomass was obtained at late exponential growth phase (18 h), when the carbon source was entirely consumed.…”

Genetic engineering for abiotic stress resistance in crop plants

“…Homologous proteins and their specific enzymatic activities from different plant species differ in terms of their temperature optima . Species-dependent temperature preferences have been reported for a number of plant proteins with diverse functions, including SOD (Nedeva et al, 1993) and Rubisco (Bose and Ghosh, 1995). When a gene of NADH-hydroxypyruvate reductase from cucumber (a species with a higher optimum growth temperature) was transformed into tobacco (a species with a lower optimum growth temperature), the optimum temperature of the pool of this enzyme in transgenic tobacco was increased (Oliver et al, 1995).…”

Glycosylated CU/ZN-Superoxide Dismutase fromKluyveromycesYeast, Determined by Mass Spectrometry

“…Several Cu/Zn SODs from different sources were isolated and investigated: yeast, from thermotolerant Kluyveromyces marxianus (8,9); fungal, from Cordyceps militaris (13), Humicola lutea (1)(2)(3) and Aspergillus niger (4). A wide variety of fungi have been shown to contain at least two forms of SOD, Cu/Zn SOD and Mn SOD (1)(2)(3)(4), and their amino acid sequences have been reported in the SwissProt, EMBL and GenBank data libraries.…”