title: Optimising growth conditions for the pectinolytic activity of Kluyveromyces wickerhamii by using response surface methodology.
abstract: This present study was undertaken to find optimum conditions of pH, temperature and, period of incubation for the pectinolytic activity of Kluyveromyces wickerhamii isolated from rotting fruits and to assess the effect of these factors by use of response surface methodology (RSM). A central composite rotatable design was used as an experimental design for the analysis of the allocation of treatment combinations. A second order polynomial regression model was fitted and was found adequate, with an R(2) of 0.94469 (P<0.001). The effects of temperature and pH were the most significant factors in influencing enzyme production. Estimated optimum conditions were as follows: pH 5.0, temperature, 32 degrees C and an incubation period of 91 h. Pectinesterase (PE), pectin lyase (PL), and cellulase activities were not detected. Pectinase production was partially constitutive. Pectin was degraded by the isolated strain of K. wickerhamii in the current study, and the pectinolytic activity is referred to as polygalacturonase (PG) activity. Crude enzyme extract was thermostable at various temperatures and, stimulated by the presence of Ca(2+) ions but inhibited by other ions like Mg(2+), Zn(2+), Co(2+), Mn(2+) and Na(+).
authors.affiliation: Department of Biological Sciences, University of Botswana, Private Bag UB00704, Gaborone, Botswana.
authors.forename: S
authors.initials: S
authors.lastname: Moyo
authors.forename: B A
authors.initials: BA
authors.lastname: Gashe
authors.forename: E K
authors.initials: EK
authors.lastname: Collison
authors.forename: S
authors.initials: S
authors.lastname: Mpuchane
mesh_terms: D001431:Bacteriological Techniques; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D005516:Food Microbiology; D005638:Fruit / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D007716:Kluyveromyces / Q000201:enzymology* / Q000254:growth & development*; D008954:Models, Biological; D011096:Polygalacturonase / Q000378:metabolism; D011133:Polysaccharide-Lyases / Q000378:metabolism; D012044:Regression Analysis; D013696:Temperature
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D011096:Polygalacturonase; D011133:Polysaccharide-Lyases; C027349:pectin lyase