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Complex substrates always induce substantial amount of enzyme production during hydrolysis by microorganisms. In this study, ghee was taken for its saturated fatty acid content and analyzed as an inducer for the production of lipase. With ghee emulsion, the bacterium Pseudomonas aeruginosa at optimal condition produced 60 units/min/L at 72 h. With olive oil emulsion, this organism produced only 41 units/min/L as maximum at 96 h. The saturated fatty acids present in ghee make it a hard substance for hydrolysis, which is the reason for the increased enzyme production. This was evaluated by the iodine number experiment. Ghee can also reduce the production cost whereas the costlier olive oil constitutes 25–50% of the total production cost for a commercial scale. The experimental results showed that the saturated fatty acids play an important role in lipase enzyme induction by P. aeruginosa. The use of ghee is cost‐effective; hence, it can be used as a potential inducer for lipase production. PRACTICAL APPLICATIONS Lipases are industrially very important enzymes. They are used in pharmaceutical, food, soap and other industries. In lipase production, olive oil is the main constituent. Comparatively, olive oil is costlier; hence, it increases the production cost of lipase. So, this study was done to replace olive oil with a much cheaper ghee using Pseudomonas aeruginosa. The ghee‐containing medium gave a very good result because of the presence of complex saturated fatty acids. The ghee‐containing medium produced 60 units/min/L at 72 h. The olive oil medium, which contains mainly unsaturated fatty acids, produced only 41 units/min/L as maximum at 96 h. Hence, in the commercial scale, ghee can reduce raw material cost as well as operation time cost significantly when it is used as substrate.

Microalgae biomass are considered as sustainable sources for various bioactive compounds. The objective of this study to evaluate the defatted biomass of green microalga Scenedesmus quadricauda KDPSC2 as a source for enhancement of total phenolic content (TPC) and antioxidant activity by microbial fermentation. Ultrasonic assisted hydrolysate was prepared from defatted biomass using ultrasound power density of 0.3 Wcm-2 at 10 min. Then the prepared defatted biomass hydrolysate (DBH) was used as soul medium for fermentation by five different microbial strains such as Bacillus amyloliquefaciens, B. stearothermophilus, B. subtilis, Saccharomyces cerevisiae NITTS1 and Cyberlindnera jadinii MMS7. Among these microbial strains, C. jadinii MMS7 was selected for further study because it was enhanced the TPC and antioxidant activity of DBH by fermentation. Besides, the fermentation conditions were optimized by classical method of optimization and found the pH 5.5, temperature 35 oC, agitation speed 150 rpm and 36 h as optimum physical parameters for enhancing the TPC and antioxidant activity of DBH by fermentation using C .jadinii MMS7. At these optimum conditions, 4.67 fold DPPH radical scavenging activity was obtained from DBH after fermentation. Therefore, this study demonstrates that the defatted biomass of S. quadricauda KDPSC2 could be a useful source for production of TPC by C. jadinii MMS7 fermentation. Keywords:  Cyberlindnera jadinii, Defatted biomass, Fermentation, Hydrolysate, Scenedesmus quadricauda, Total phenolic content.