Substrate effects in tower loop reactors

Summary Hansenula polymorpha was cultivated in a bubble column loop bioreactor employing ethanol and/or glucose as substrates. By varying the substrate concentration, the cultivations were carried out in non-limited, substrate limited and oxygen transfer limited growth ranges. The influence of the transitions from one range to another on reactor performance (OTR,k _L a, a) and cell productivity () were investigated. When employing ethanol as a substrate, the concentration considerably influences the fluid dynamics, mass transfer phenomena and cell productivity. When employing glucose as a substrate, glucose repression occurs. At high glucose concentrations no transition into the oxygen transfer limited growth is possible. The ethanol produced during the glucose repression influences the fluid dynamics, mass transfer phenomena and productivity. With decreasing glucose concentration the glucose repression can be gradually eliminated.     

Foam behaviour of biological media

Summary A simple method was developed for evaluating foam stability. The influence of KCl and MgSO₄ on foam stability of bovine serum albumin foams was investigated. These salts increase foaminess, but diminish foam stability by the same degree. Thus there is little overall.     

Effect of sensory stimulation on the lamina V pyramidal neurons of the gyrus cinguli in the rat

Three groups of Wistar-rats were exposed to permanent noise (80 db) during different periods in their postnatal life: the first group was exposed starting from birth for a period of four weeks, the second one from birth up to nine weeks of age and the third group from the fifth up to the ninth week postnatal. A fourth group (control animals) was reared under normal laboratory conditions. After the experiments the brains were exposed to a modified GOLGI-method. In lamina-V-pyramids of the gyrus cinguli lightmicroscopical results: length, number and distribution of spines on the main apical dendrites and on the apical dendritic branches where evaluated. Main results: 1. Permanent noise during the early postnatal development phase of the brain of rats (from birth up to the fourth week of age) causes a statistically significant increase of apical spines. The spines-values are 20% above those of the control animals. 2. Permanent noise from birth up to the ninth week of age or applied only during the later postnatal period (from the fifth week up to the ninth week of age) does not significantly alterate the spines-value. 3. The results are estimated as a consequence of extreme environmental factors causing effects, comparable with an universal stress reaction. Conclusions were discussed in comparison to the results of other authors.     

A new progestin (Sa 45.249) for cycle control in pigs communication I: Hormonal activities and dosage

Sa 45.249 was applied for 12 days to groups of ten gilts each. A daily dose of 3, 6, 12 or 24 mg inhibited cyclic functions effectively; estrus was observed 4.5 ± 0.8, 4.8 ± 0.8, 5.2 ± 0.9 and 6.1 ± 0.6 days after cessation of treatment, respectively. All animals were slaughtered 8 days after induced estrus. Only animals treated with 3 mg showed a high incidence of ovarian cysts simultaneously with the occurrence of corpora lutea. In animals treated with higher dosages, only one (6 mg) had 4 cystic follicles, but simultaneously 12 corpora lutea. In another study, the effectiveness of Sa 45.249, applied at different doses, for differing time periods, and starting at different days of the cycle, was investigated. Doses ranged from 3 to 9 mg/day, duration of treatment from 8 to 16 days and treatments commenced on days 2, 5, 10, 15 or 19 of the cycle. An increase in the daily doses of 1 mg resulted in a delay of estrus of less than 0.1 day. Of 99 gilts, 93 showed an estrus 6.5 ± 1.7 days after cessation of treatment. None of the variables studied had a significant effect on the occurrence of estrus or the interval between treatment and the onset of heat.     

Process optimization of a continuous airlift tower-loop reactor

Based on the experimental investigations with H. polymorpha and Methylomonas M 15 in bench-scale airlift tower-loop reactors, a general distributed parameter model was developed and used to simulate to cultivation process in a 40-m-high production reactor. This general model was simplified with regard to the gas phase and loop balances and was employed to optimize cell productivity and/or profit in a 20-m-high pilot-plant airlift tower-loop reactor. Maximum cell productivity always occurs in the oxygen-transfer-limited growth range. In case of a high "penalty factor" for nonconsumed substrate, maximum profit is attained at the boundary between substrate and oxygen-transfer-limited growth. Oxygen-transfer limitation exists in the lower half of the tower, whereas in the upper half, substrate limitation prevails. The longitudinal dissolved oxygen concentration passes a minimum in this case as has been determined experimentally in the bench-scale column. The simulation results agree fairly well with the data measured in the pilot plant.     

Cell recovery by continuous flotation

Summary Cell recovery by means of continuous flotation of the Hansenula polymorpha cultivation medium without additives was investigated as a function of the cultivation conditions as well as of the flotation equipment construction and flotation operational parameters. The cell enrichment and separation is improved at high liquid residence times, high aeration rates, small bubble sizes, increasing height of the aerated column, and diameter of the foam column. Increasing cell age and cultivation with nitrogen limitation reduce the cell separation.Symbols C_P cell mass concentration in medium g·l^–1 - C_R cell mass concentration in residue g·l^–1 - C_S cell mass concentration in foam liquid g·l^–1 - V equilibrium foam volume cm³ - V gas flow rate through the aerated liquid column cm³·s^–1 - V_F feed rate to the flotation column ml/min - ¹ V _S/V foaminess s - mean liquid residence time in the column s     

A simple and fast method for the preparation of the human cardiac myosin light chains

A simple and fast method is presented for the isolation and separation of human cardiac myosin light chains. The method requires only a crude myosin for splitting into heavy and light chains. The separation of the light chains is made by isoelectric precipitation with good yield.