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Gastrointestinal ontogenetic studies constitute one of the basic and important investigations related to the nutrition of aquatic animals. In this investigation, specimens of the western white shrimp (Litopenaeus vannamei) at different developmental stages (from nauplius 1 to postlarvae 120) were assayed for the activities of digestive enzymes. According to the results, at all developmental stages, trypsin, amylase, and lipase enzymes were found to be active. In addition, the peak activities of all enzymes were revealed to occur during the late zoea larval stages (Z3). On the other hand, minimum activities were observed to occur at metamorphosis. During the postlarval developmental stages, amylase and lipase activities increased steadily, whereas the trypsin activity was more or less constant up to the eighteenth week. In conclusion, ontogenetic change in digestive enzyme activity may reflect either a developmentally cued change in enzyme synthesis or a secondary effect of change in the function and relative size of the midgut during its differentiation.
 
 
 
 

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Gamma-decalactone, an intramolecular 4-hydroxydecanoic acid ester, has a peach-like aroma and is widely used in the food and cosmetics industries. The biotechnological production of this compound is possible via biotransformation of castor seed oil by the yeast Yarrowia lipolytica. This study aimed to compare the production of gamma-decalactone by wild-type strain with that in a mutant strain producing lipase in high amounts. It was found that cells with yeast-like morphology produce more gamma-decalactone than hyphae-like cells. The maximum production of gamma-decalactone by wild-type and mutant strains was 65 mg/L after 24h of inoculation and 90 mg/L after 72h of inoculation, respectively. The mutant strain converts 38% more substrate into gamma-decalactone than the wild-type strain, therefore, it could significantly increase the productivity of industrial-scale production of gamma-decalactone.