Abstract: A method for producing mevinolin by a microorganism in a fermentation process having a seed culture stage and a main fermentation stage, including a) cultivating a microorganism biomass in the seed culture stage to produce an inoculum; b) transferring the inoculum into a fermentation medium in the main fermentation stage; and, c) maintaining steady stage conditions in the main fermentation stage, thereby producing a fermentation broth containing mevinolin. Preferably, the steady state conditions are maintained in the main fermentation stage by one or more of feeding of organic carbon sources; controlling glucose and/or total reducing sugar content; feeding of organic nitrogen sources; controlling pH; controlling foam level; controlling the mass of the fermentation broth by withdrawals and feedings; and, controlling the dissolved oxygen level.

Abstract: A method for producing lovastatin by a microorganism in a fermentation process having a seed culture stage and a main fermentation stage, including a) cultivating a microorganism biomass in the seed culture stage to produce an inoculum; b) transferring the inoculum into a fermentation medium in the main fermentation stage; and, c) maintaining steady stage conditions in the main fermentation stage, thereby producing a fermentation broth containing lovastatin. Preferably, the steady state conditions are maintained in the main fermentation stage by one or more of feeding of organic carbon sources; controlling glucose and/or total reducing sugar content; feeding of organic and/or inorganic nitrogen sources; controlling pH; controlling foam level; controlling the mass of the fermentation broth by withdrawals and feedings; and, controlling the dissolved oxygen level.

Abstract: A mixing device, especially for a fermenter, capable of dispersing gas in a broth therein, in which a number of propeller mixers are provided on a vertically extending shaft. The lower propeller mixer is a gas dispersing mixer having a hollow hub and open channels on the blades extending from this hub and tapering outwardly. At least one intermediate propeller mixer has some blades shorter than others and of reverse flow direction, some blades having baffle bars on trail edges thereof. The upper propeller mixer has the longer blades without channels and flow modifying elements.

Abstract: The invention refers to a new microbial process for preparing .beta.,.delta.-dihydroxy-7-[1,2,6,7,8,8a-hexahydro-2.6-dimethyl-8-(2-methy l-butyryloxy)-naphthalen-1-yl]-heptanoic acid .delta.-lactone of formula (I) and .beta.,.delta.-dihydroxy-7-[1,2,6,7,8,8a-hexahydro-2.6-dimethyl-8-(2-methy lbutyryloxy)-naphtalen-1-yl]-heptanoic acid of formula (II), ##STR1## by the aerobic fermentation of the submerged culture of an imperfect fungus strain biosynthesizing the above compounds, in a nutrient medium containing utilizable carbon and nitrogen sources as well as mineral salts, and by isolating the product of formula (I), which comprises cultivating a strain of the new Aspergillus obscurus fungus species producing the above compound(s) of formulas (I) and/or (II), in a temperature range of 25.degree. to 30.degree. C. and, if desired, separating the product(s) formed from the fermentation broth, then isolating it in the lactone form of formula (I) and, if desired, purifying the same.

Abstract: Complex mixing system with stages consisting of propeller mixers of high diameter ratio, where the blades are provided with flow modifying elements, whereby the energy proportions spent on dispersion of the amount of gas injected into the reactor, homogenization of the multi-phase mixtures, suspension of solid particles, etc. and the properties corresponding to the rheological properties of the gas-liquid mixtures and to the special requirements of the processes can be ensured even in extreme cases. Open channels (5) opposite to the direction of rotation are on the blades (4) of the dispersing stage (2a) of the propeller mixers (2) fixed to a common shaft, where the channels (5) are interconnected with gas inlet (7). The angle of incidence of a certain part of the blades (4) of mixing stages (2b, 2d) used for homogenization and suspension is of opposite direction and the length is shorter and/or the angle of incidence is smaller than those of the other blades.

Abstract: The invention relates to a process for the preparation of an oxytetracycline-calcium silicate complex salt from fermentation broth.By the process according to the invention the valuable antibiotic oxytetracycline may be separated from the fermentation broth in an easy manner. The complex obtained according to (a) contains up to 50% of antibiotic and is suitable for the processing in the pharmaceutical industry while the product according to (b) contains 10 to 20% of antibiotic and may be used as fodder additive directly.

Abstract: The invention relates to a new process for the preparation of easy-flowing (flowable) oxytetracyclin hydrochloride. According to the process of the invention, the crude, dry or filter-wet oxytetracyclin hydrochloride consisting of needle-shaped crystals is boiled with an organic solvent forming an azeotropic mixture with water, optionally a part of the solvent is distilled off in a form of an azeotropic mixture, then the mixture is cooled and the precipitated oxytetracyclin hydrochloride consisting of spherical crystals is separated and dried.Oxytetracyclin hydrochloride exists in two various crystal forms, the one of which is needle-shaped, while the other one consists of orthorhombic sheets. The crystals of this latter form are capable of forming spherical particles by coalescence. The crystal form consisting of spherical particles is much more useful for the pharmaceutical industry.