title: Screening and characterization of amylase and cellulase activities in psychrotolerant yeasts.
abstract: BACKGROUND
  Amylases and cellulases have great potential for application in industries such as food, detergent, laundry, textile, baking and biofuels. A common requirement in these fields is to reduce the temperatures of the processes, leading to a continuous search for microorganisms that secrete cold-active amylases and cellulases. Psychrotolerant yeasts are good candidates because they inhabit cold-environments. In this work, we analyzed the ability of yeasts isolated from the Antarctic region to grow on starch or carboxymethylcellulose, and their potential extracellular amylases and cellulases.
  
  
  RESULTS
  All tested yeasts were able to grow with soluble starch or carboxymethylcellulose as the sole carbon source; however, not all of them produced ethanol by fermentation of these carbon sources. For the majority of the yeast species, the extracellular amylase or cellulase activity was higher when cultured in medium supplemented with glucose rather than with soluble starch or carboxymethylcellulose. Additionally, higher amylase activities were observed when tested at pH 5.4 and 6.2, and at 30-37 °C, except for Rhodotorula glacialis that showed elevated activity at 10-22 °C. In general, cellulase activity was high until pH 6.2 and between 22-37 °C, while the sample from Mrakia blollopis showed high activity at 4-22 °C. Peptide mass fingerprinting analysis of a potential amylase from Tetracladium sp. of about 70 kDa, showed several peptides with positive matches with glucoamylases from other fungi.
  
  
  CONCLUSIONS
  Almost all yeast species showed extracellular amylase or cellulase activity, and an inducing effect by the respective substrate was observed in a minor number of yeasts. These enzymatic activities were higher at 30 °C in most yeast, with highest amylase and cellulase activity in Tetracladium sp. and M. gelida, respectively. However, Rh. glacialis and M. blollopis displayed high amylase or cellulase activity, respectively, under 22 °C. In this sense, these yeasts are interesting candidates for industrial processes that require lower temperatures.
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile. mario.carrasco.t@gmail.com.
authors.forename: Mario
authors.initials: M
authors.lastname: Carrasco
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile. pablovillarreal07@gmail.com.
authors.forename: Pablo
authors.initials: P
authors.lastname: Villarreal
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile. barahona.salvador@gmail.com.
authors.forename: Salvador
authors.initials: S
authors.lastname: Barahona
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile. jalcainog@u.uchile.cl.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Alcaíno
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile. vcifuentes@uchile.cl.
authors.forename: Víctor
authors.initials: V
authors.lastname: Cifuentes
authors.affiliation: Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago, Chile. mbaeza@u.uchile.cl.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Baeza
mesh_terms: D000681:Amylases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000864:Antarctic Regions; D044602:Cellulases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D013696:Temperature; D015003:Yeasts / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D005656:Fungal Proteins; D000681:Amylases; D044602:Cellulases