Cell aggregation as a trigger for enhancement of intracellular lipase production by a Rhizopus species

Abstract

Immobilization of Rhizopus chinensis cells in various Biomass support particles (BSPs) made from polyurethane, nylon, polyester, stainless steel, polyvinyl alcohol, and cellulose enhanced intracellular lipase activity as much as several-fold that of freely suspended cells irrespective of the BSP material. In freely suspended cultivation the overall intracellular lipase activity of free cells, consisting of pellet cells and pulp-like cells, increased with an increase in the ratio of pellet cells to pulp-like cells. It was thus considered that cell aggregation seems to be a principal factor in the enhancement of intracellular lipase formation by Rh. chinensis. Also, other Rhizopus species such as Rh. javanicus, Rh. delemar, Rh. oligosporus, Rh. niveus, Rh. japonicus and Rh. oryzae were immobilized in both polyurethane and cellulose BSPs, In all species used, intracellular lipase production was significantly enhanced compared to results without immobilization. Cell aggregation therefore seems to be a common trigger for the enhancement of intracellular lipase production by Rhizopus species.