NOVELTY - Preparing a compound or composition by using microorganisms, comprises: (a) providing a microorganism capable of producing the compound or composition; (b) culturing the microorganism under a first cultivation condition for 8-30 hours; (c) culturing the microorganism under a second cultivation condition for 8-30 hours; (d) alternating steps (b) and (c) to generate a culture of the microorganism that exhibits a rhythmic production with circadian periodicity; (e) arresting the cultivation of microorganism during or after the rhythmic production; and (f) recovering the compound or composition.    USE - The process is useful for preparing a compound or composition, where: the compound is an enzyme, a drug, a biosurfactant, a flavoring compound, a monomer for producing synthetic polymers or a biofuel; and the composition is a microbial fermentation product comprising miso, soy sauce, tofu, tempeh, beer, bread, sake, sourdough, rice wine, whisky, vodka, silage, pickle, sauerkraut, wine, vinegar, cider, mead, cheese, kefir, quark, fresh cream, yogurt, fish sauce, shrimp paste, salami and prosciutto, and a mixture of chemical variants of an antibiotic compound (all claimed).    ADVANTAGE - The composition provided by the process exhibits improved odor and/or taste characteristics. The process provides compound or composition with improved yield and/or purity.    DETAILED DESCRIPTION - Preparing a compound or composition by using microorganisms, comprises: (a) providing a microorganism capable of producing the compound or composition in a cultivation medium; (b) culturing the microorganism under a first cultivation condition for 8-30 hours; (c) culturing the microorganism under a second cultivation condition for 8-30 hours; (d) alternating steps (b) and (c) to generate a culture of the microorganism that exhibits a rhythmic production with circadian periodicity with respect to the compound or composition; (e) arresting the cultivation of the microorganism during or after the rhythmic production; and (f) recovering the compound or composition from the culture. An INDEPENDENT CLAIM is included for composition obtainable by the process.