Under certain conditons, the bacterium of this investigation produced large amounts of exopolymer when grown in the permissive medium Trypticase Soy broth. Exopolymer production occurred throughout the growth period of the bacterium. By the onset of stationary phase, the total yield for a particular culture had been realized, and the amount of recoverable exopolymer declined thereafter. Exopolymer production was lost on repeated transfers of the cells in the permissive medium. But large amounts of exopolymer were produced if the bacterium was first grown in a nonpermissive medium to the onset of the stationary phase and was then allowed to persist for a suitable period of time in this medium, a period referred to here as ‘aging, ’ before being inoculated into the permissive medium. During this aging period, the potential for exopolymer production accumulated. The accumulation was preceded by a lag period and followed by a decline period. The length of each of these periods differed according to the history of the starter culture and the number of transfers, i.e. cell generations, prior to aging. The amount of exopolymer generated by aged cells increased with increasing inoculum size, within certain limits. The potential accumulated during the aging period could be reduced by further growth and cell divisions in the nonpermissive medium prior to inoculation into the permissive medium. The accumulation of potential for exopolymer production occurred in the presence of chloramphenicol. The amount of exopolymer produced increased with increasing strength of Trypticase Soy broth and, more specifically, was directly related to the glucose concentration of the medium.
Activated sludge which had been subjected to an anaerobic-aerobic cycle showed high rates of anaerobic release of phosphate, followed by excess phosphate uptake under aerobic conditions. Addition of carbon and energy sources was essential to anaerobic release of phosphate, and no significant release of phosphate occurred in the absence of added substrates. Heating activated sludge (90°C for 2min) strongly inhibited anaerobic release of phosphate. Treatment of activated sludge with chemical reagents including sodium hypochlorite, benzalkonium chloride and ethanol greatly inhibited phosphate release. Increasing the osmotic pressure in the medium adding sodium chloride and sucrose also inhibited the release. These results showed that the anaerobic release of phosphate from activated sludge which had been acclimated to an anaerobic-aerobic cycle is principally attributable to a biological mechanism.
Glycopeptides from the microplasmodia of Physarum polycephalum grown in the presence of [3H]mannose or [3H]glucosamine were characterized by gel-filtration, anion-exchange and lectin-affinity chromatography before and after enzymatic or chemical treatment. Various types of glycopeptide were found in the growing plasmodia as shown by Con A affinity column chromatography, while pulse-labeled precursors were composed mainly of mannose-rich glycopeptides which were sensitive to endo H and α-mannosidase. During the processing of the glycoprotein, the mannose-rich glycopeptides changed to larger glycopeptides which were resistant to endo H and α-mannosidase. These processing reactions of the glycoprotein appeared to be blocked when the plasmodia underwent differentiation to macrocysts.
Staphylococcus aureus synthesizes two kinds of intracellular nucleases besides the well-known heat-stable extracellular nuclease. Apparently, these intracellular enzymes have many properties in common with the extracellular nuclease implying that they may have precursor-product relationships. To get an insight into the relationships (if any) the enzymes were purified and their properties were compared. Detailed analysis of the properties together with immunological studies indicated that the enzymes are distinct from one another, so neither of the intracellular nucleases could be a precursor for the extracellular nuclease.
The new mutant Trichoderma reesei E-12 was better than the parent strain QM 9414 and strain D1/6 in terms of cellulase productivity. Due to its greater resistance to catabolite repression there was scope for further improvement of enzyme productivity by better control of the environment inside the bioreactor. Mutant E-12 requires higher nitrogen concentration than other strains. A peptone concentration of 0.2% minimizes the foaming problem and the drop in filter paper activity at the decreased peptone level is not significant. The mutant strain has a potential for enhanced cellulase biosynthesis with better environmental control strategies.
We report here the action of the β-glucosidase, nitrite hydratase and amidase of Brevibacterium sp. R 312 during the in vitro degradation of some cyanoglucosides. The degradation pathway found for prunassin begins with the action of the β-glucosidase followed by the action of the nitrite hydratase and of the amidase, but linamarin can also be attacked first by the nitrite hydratase. The Vm and Km of the nitrite hydratase for the main nitrite compounds and of the β-glucosidase for cyanoglucosides were determined with partially purified extracts.
Whole-cell pastes of Pichia, equipped with the coenzyme Q7, were spectrophotometrically analyzed (38 species). The low-temperature absorption cytochrome spectra showed a great diversity of response. The typical α1 peak of cytochrome c (545-546.5nm) might be complemented in a few species by a less pronounced α2 peak (544-545nm). The cytochrome oxidase peak (a+a3) was rarely typical and symmetric and showed two noticeable peculiarities: -an unsymmetrical peak with the main absorption range from 597.5 to 602.5nm and a shoulder at the lower or upper wavelength, and a double peak of cytochrome oxydase (596-598.5nm)-(605-607nm) or (593-594nm)-(601-602nm) rarely seen elsewhere in the yeasts. These characteristics, associated with GC contents, led to the identification of 3 main groups in the genus Pichia concerning at least 35 species.