Variability of the lipolytic activity in Yarrowia lipolytica and its dependence on environmental conditions

This work was aimed to the evaluation of the variability of lipolytic activ ity in Yarrowia lipolytica strains, as well as to asses for a selected stra in, the response to the changes of physico-chemical variables (such as pH, NaCl and lipid content), in order to obtain predictive models describing th eir effects on the lipolysis pattern. The strains tested, having different environmental origin, showed different patterns of the free fatty acids (FF A) released. The clustering of the free fatty acids profiles evidenced that the unweighted average distance within the strains of the same species did not exceeded 30%. However, the lipolytic activity of some strains generate d FFA profiles that differentiated from the majority of the strains conside red. Also, when a single strain was inoculated in model systems in which pH , NaCl and milk fat were modulated according to a Central Composite Design (CCD), chemico-physical characteristics of the system led to marked variati ons in the lipolytic activity with consequent changes in individual fatty a cids released. In most cases, when the same Y. lipolytica strain was used, under the exper imental conditions adopted, the modulation of the lactic acid, NaCI and lip id content did not generate differences in the fatty acid release exceeding 20-21%. However, some combinations of factors remarkably affected lipase e xpression or activity, and generated differences in the fatty acid released higher than those observed among different strains of the same species. (C ) 2001 Elsevier Science B.V. All rights reserved.