Abstract: A process for producing citric acid/citrate for use in producing citric acid, comprising the steps of continuously feeding to a fermenter containing a yeast capable of transforming glucose to citric acid by fermentation, in the presence of a nutrient medium and oxygen, sugar, especially glucose as a C source and at least one ammoniun compound as an N source fermenting the sugar to citric acid in said fermenter at a temperature, a pH and with a residence time sufficient to transform at least a major part of the sugar continuously fed to said fermenter to citric acid continuously withdrawing fermentation product from said fermenter recovering citric acid/citrate from said fermentation product controlling a C/N ratio fed to said fermenter to correspond to a molar ratio of glucose to ammonium compounds of 12 to 22 during fermentation of the glucose to citrate.

Abstract: Strains of Aureobasidium pullulans (de bary) Arnaud can be used for the commercial production of gluconic acid by fermentation in aqueous liquid containing sugar, which in continuous culture from glucose form greater than or equal to 90% and greater than or equal to 90% molar selectivity. The process is conducted with an Fe and Mn optimized medium with a nitrogen-independent (N-independent) ion concentration. The iron (Fe) concentration with 3 g/l NH.sub.4 Cl is greater than or equal to 0.5 mM, and the manganese (Mn) concentration with 3 g/l NH.sub.4 Cl is greater than or equal to about 0.5 mM manganese (Mn). The pH is regulated between about 4.5 and about 8, in particular at 6.5-7, and the temperature between 24 and 32.degree. C., in particular at 29-30.degree. C. Particularly successful strains are Aureobasidium pullulans (de bary) Arnaud with the registration numbers DSM 7085, DSM 7086, DSM 7087, and DSM 7088.

Abstract: For the immobilization of micro-organisms and animal cells, in particular for anaerobic processes, such as the purification of waste water or for the biotechnological production of nutrition-essential or pharmacological substances, porous, sintered bodies are employed (inorganic carrier bodies). In particular, sintered glass in the form of Raschig rings with a double-pore structure, are employed. They have porosity-determining through-going macropores that permit a free exchange of fluid and gas from the interior of the carrier to the surroundings, and open micropores within the macropore walls, the diameter of the micropores being of the same order of magnitude as the size of the micro-organisms or cells. These carrier bodies typically have an open pore volume of 35% to 85%, 20% to 80% being accounted for by the macropores having a diameter of 20 to 500 .mu.m, and 5%-50% by micropores having a diameter of 1-10 .mu.m.

Abstract: A fixed bed layer of a reactor column for the execution of anaerobic decosition processes, which column is divided by screen partitions into segments one above another with intermediate spaces for gas discharge from the column through discharge funnels into one or more corresponding, ascending pipes. Additional devices for the introduction of liquid or gas into the individual fixed bed segments produce turbulence and remove excess sludge from the fixed bed layer. Annular guide elements project from the inner wall of the column underneath the funnel and have a constricted cross section which defines an annular channel to the next column segment. Thus, a liquid stream is not blocked during optimal gas collection in the funnel. The funnels are preferably installed in the screen floor of the subsequent column segment.

Abstract: Process and apparatus for the continuous anaerobic decomposition of organic compounds in an aqueous liquid is effected, in accordance with the invention, in a fixed-bed reactor by microorganisms, which are grown upon a support with the admixture of recycled reactor discharge in such an amount that practically uniform conditions exist throughout the reactor. The volume/time yield can be increased to a surprisingly large extent by means of the process if, after breeding sufficient adhering microorganisms with a residence time equal to or greater than 50% of the doubling time, an iterative reduction is efected in the residence time with the onset of equilibrium conditions at each stage until the volume/time yield can be increased no further.