Extracellular protease from the antarctic yeast Candida humicola

Abstract

The psychrotrophic, dimorphic yeast Candida humicola, isolated from Antarctic soil, secretes an acidic protease into the medium. The secretion of this protease by C. humicola was found to be dependent on the composition of the medium. In YPD or yeast nitrogen base medium containing either amino acids or ammonium sulfate as the nitrogen source, the activity of the protease in the medium was low (basal level). However, when yeast nitrogen base medium was depleted of amino acids or ammonium sulfate and supplemented with proteins, the activity of the enzyme increased. The secretion of the enzyme was greater during exponential growth at low temperatures than during growth at higher temperatures. The purified protease had a molecular mass of 36,000 Da and was inhibited by pepstatin, iodoacetamide, and sodium dodecyl sulfate. Despite the prevalent cold temperatures in Antarctica, this extracellular protease of the psychrotrophic yeast C. humicola was active at temperatures ranging from 0 to 45'C, with an optimum activity at 37'C.

Extracellular enzymatic activity profiles in yeast and yeast-like strains isolated from tropical environments

“…The production of yeast proteases has so far been studied mainly for their implications in the beer and wine industry (Bilinski and Stewart 1990;Dizy and Bisson 2000;Strauss et al 2001). Only a few yeast proteases have been studied for alternative potential applications (Ray et al 1992;Poza et al 2001). The frequency of proteolytic ascomycetes (Table 1) was generally lower than that reported recently (Braga et al 1998;Strauss et al 2001).…”

“…The more extensively studied yeasts have been those belonging to species of oenological importance (Rosi et al 1994;Charoenchai et al 1997;Strauss et al 2001), while only a few yeasts of environmental origin have so far been studied for their biotechnological value as enzyme producers (Burden and Eveleight 1990). Although recent surveys have underlined the potential of unconventional and extreme environments as a source of natural biodiversity for the isolation and selection of useful micro-organisms (Bull et al 1992), to our knowledge, only the secretion of extracellular proteases has been studied in yeasts isolated from extreme environments (Ray et al 1992;Phaff et al 1994;Abranches et al 1997;Braga et al 1998).…”

Histidine utilisation operon (hut) is upregulated at low temperature in the antarctic psychrotrophic bacterium Pseudomonas syringae

“…Earlier it has been found that at low temperature the secretion and possibly the production of lipase and K-amylase are increased in psychrophilic bacteria [1,31^33]. The secretion of extracellular protease was also found to increase at lower temperature in the antarctic yeast Candida humicola [33] and it was postulated that the lower activity of the biodegradative enzymes would probably be compensated by higher production and/ or secretion. The identi¢cation in the present study that the hut operon is regulated by low temperature further con¢rms the above speculation and also suggests that this regulation could be at the level of transcription as in the case of the hut operon.…”

Occurrence and expression of cspA, a cold shock gene, in Antarctic psychrotropic bacteria

“…In our attempts to understand the mechanisms of cold adaptation ( [7,8,9]; unpublished results) in Antarctic psychrotrophic bacteria that grow between 0°C and 30°C we asked the questions: do the cspA homologous genes exist in various psychrotrophic bacteria? Are they expressed constitutively or induced similarly to mesophiles?…”