Culture conditions and investigation of bioreactor configurations for lipase production by rhizopus oryzae

Lipolytic enzymes are the subject of great industrial and academic interest. For this reason, a detailed study of lipolytic enzyme production by the fungus Rhizopus oryzae is tackled, and several steps from plate to shake flasks and bioreactor cultures are investigated in order to propose an optimized strategy to perform the biological process. The suitability of several lipidic compounds and surfactants is assessed. Triton X-100 (5 g/L) gives the highest activities with a maximum value of 6320 U/L which is 10-fold the value attained in cultures without addition of lipidic compounds. As there are almost no studies on bench-scale bioreactors, two bioreactor configurations, stirred tank and air-lift, are investigated to determine the most suitable one to carry out the biological reaction. It is demonstrated that the lipolytic activity is strongly enhanced when a stirred-tank bioreactor is used with a maximum value of 3521 U/L within two days which is clearly higher than the values produced by other recently reported species.XUNTA de Galicia | Ref. PGIDIT06 PXIB314376P

Biodegradation and utilization of waste cooking oil by Yarrowia lipolytica CECT 1240

Biodegradation of waste cooking oil and its application as lipase production inducer in cultures of Yarrowia lipolytica CECT 1240 have been investigated, both in shake flasks and a bench-scale bioreactor. The ability of this strain to degrade the spent oil was evaluated by monitoring COD throughout the cultures, and a remarkable decrease was recorded (almost 90% decrease in oil COD after 3 days in bioreactor). Moreover, the addition of waste cooking oil to the medium led to a significant augmentation in extracellular lipase production by the yeast, compared to oil-free cultures. This confirms the suitability of the studied residue as an inducer of lipase biosynthesis, which is a very interesting fact, from an economic standpoint. These results were confirmed when a fed-batch strategy was proposed. Finally, some properties of the crude enzyme were studied, and compared to the enzymes obtained when non-used oil was added to the medium.Practical application: New strategies to valorize wastes from the food and agro industries are attracting a great scientific interest due to the important advantages offered from an economic and environmental point of view. For this reason, the yeast Yarrowia lipolytica CECT 1240 is proposed for degrading waste cooking oils. This approach entails also another benefit in terms of lipolytic enzyme synthesis, since the addition of used up oils has a lipase inducer effect. The enormous interest in lipases is reflected in the number of applications that they present. The process was successfully carried out both in shake flasks and a bench-scale bioreactor, allowing producing high levels of lipolytic activity at the same time that the COD was diminished up to nearly 90%Xunta de Galicia | Ref. PGIDIT06PXIB314376P