| Popis: |
The separation of a commercially obtained lipase and a bacterially obtained lipase were investigated by examining their ability to adsorb to, and be desorbed from, lipid/non-lipid particles and silanised 'Ballotini' glass particles. Lipase P from Pseudomonas fluorescens SAM-2, which was later reclassified by the manufacturer as lipase PS from Pseudomonas cepacia, was used as a commercially purified lipase for initial adsorption and desorption experiments. Particles of coconut oil, paraffin wax and paraffin oil were produced by emulsification and lipase P was adsorbed and desorbed from them. The emulsified particles were considered unsatisfactory for further experimentation owing to an inability to calculate the specific surface area per unit weight of particles. 'Ballotini' particles with a mean diameter of 213 μm and a specific surface area of 9.53 ± 0.22 m2/kg were shown to be made to behave in the same manner as fat and oil emulsions. The adsorption onto the 'Ballotini' followed a Langmuir isotherm with p to 4,900 U/m2 of lipase PS at 65% adsorption, and 12,900 U/m2 at 25% adsorption. The adsorption was not highly pH dependent since there was good adsorption from pH 4 to pH 9. A wide range of potential desorption agents were tested and the non-ionic surfactants tween 20 and triton X-100 proved to be the best with up to 85% desorption of lipase. Lipase was produced from Pseudomonas aeruginosa L130 (NCIMB 12718) in nutrient broth and also in defined media. The lipase production was induced by glycerol, even in the absence of lipids giving a maximum of 5.9 ± 0.2 U/mL in nutrient broth, but only 0.3 ± 0.1 U/mL in the defined media. The adsorption and desorption of the bacterial lipase from silanised glass particles was very poor with only 536 U/m2 of lipase at 23% adsorption being achieved. The poor separation of the bacterial lipase was believed to result from microbially produced components that inhibited adsorption. |
