Effect of pH on physiology of Metarhizium anisopliae for production of swainsonine.

The effect of pH on the production of swainsonine and fungal morphology at different stages of fermentation of Metarhizium anisopliae was investigated. When no control was applied, the pH of the culture dropped from 6.5 to 3.

Regional and molecular separation of the four bioactivities of 'tribulin'.

The endocoid tribulin has four known bioactivities: monoamine oxidase A and B inhibitory activities (MAO-AI and MAO-BI) and peripheral and central benzodiazepine receptor binding inhibitory activities (PBR-I and CBR-I). Analysis of the four bioactivities in rat tissue reveals regional dissociation. Most notably liver was particularly rich in PBR-I yet contained no detectable MAO-AI.

The application of aqueous two-phase systems to oligosaccharide synthesis by alpha-mannosidase catalysed glycosyl transfer reactions.

Aqueous two-phase systems formed from PEG and dextran have been applied to the synthesis of oligosaccharide by Jack bean alpha-mannosidase in reverse. Whilst rates of synthesis and percentage yields were similar in two-phase systems and one-phase aqueous buffer systems, a ten-fold increase in yield of product per unit of enzyme was seen. In addition, the use of aqueous two-phase systems offers potential process advantages over one-phase systems for the synthesis of oligosaccharides.

pH regulation of penicillin production in Aspergillus nidulans.

As shown by both bioassay and high-performance liquid chromatographic (HPLC) analysis, penicillin G production by Aspergillus nidulans is subject to regulation by the pH of the growth medium. Penicillin titres were highest at alkaline pH and in strains carrying mutations in the regulatory gene pacC which mimics the effects of growth at alkaline pH. They were lowest at acid pH and in strains carrying mutations in the palA, palB, palC, palE or palF genes which mimic the effects of growth at acid pH.

Isolation of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine from culture broths by covalent chromatography.

An efficient procedure for the isolation of reduced delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV) from culture supernatants of beta-lactam antibiotic-producing microorganisms is described. The method utilises covalent chromatography to isolate thiols from culture broths that have been deproteinised and undergone borohydride reduction. 2-Pyridyl disulphide activated thiopropyl Sepharose was employed batchwise to isolate the thiols present in such broths from cultures of the known ACV excreter Cephalosporium acremonium N2 and the penicillin producer Penicillium chrysogenum P2.