Oil accumulation and in situ trans/esterification by lipolytic fungal biomass.

The goal of this study was to increase the cost-effectiveness of oil production by an oleaginous and lipolytic strain M. circinelloides IBT-83, by optimizing both lipids accumulation in the mycelium containing intracellular lipases, and a one-step process coupling lipids extraction and enzymatic trans/esterification. In optimal conditions (culture medium composed of corn steep solids, plant oil, glucose and NO3-) over 50gd.w./dm3 of biomass containing over 60% of lipids was produced. The lipids extracted with acetone or petroleum ether contain free fatty acids and triacylglycerols. The supplementation of the second solvent with alcohol results in enzymatic trans/esterification of lipids with the yield of over 80% of esters in 1 h. To our knowledge, this is the first suggestion to convert fungal oils into esters during their extraction using intracellular lipases contained in the same fungus. What is important, it is possible to obtain a second product, lipase preparation, in this process.

Scale-up of PUF-immobilized fungal chitosanase-lipase preparation production.

Mucor circinelloides IBT-83 mycelium that exhibits both lipolytic (AL) and chitosanolytic (ACH) activities was immobilized into polyurethane foam in a 30 L laboratory fermenter. The process of immobilization was investigated in terms of the carrier porosity, its type, amount, and shape, location inside the fermenter, mixing, and aeration parameters during the culture, as well as downstream processing operations. The selected conditions allowed for immobilization of approximately 7 g of defatted and dried mycelium in 1 g of carrier, i.e., seven times more than achievable in 1 L shake-flasks. Enzymatic preparation obtained by this method exhibited both the chitosanolytic (ACH 432.5 ± 6.8 unit/g) and lipolytic (AL 150.0 ± 9.3 U/g) activities. The immobilized preparation was successfully used in chitosan hydrolysis to produce chitooligosaccharides and low molecular weight chitosan, as well as in waste fats degradation and in esters synthesis in nonaqueous media. It was found that the half-life of immobilized preparations stored at room temperature is on average of 200 days.