New trends in microbial technology.

Microbial technology includes not only the production of materials in bioreactors, or the production of new catalysts by genetic engineering but extends to aspects of both human and animal health care, waste and pollution management, enhanced oil recovery, mineral leaching, advanced plant breeding, diagnostics and analytical equipment, biosensors, bioelectronics and renewable energy system based on biomass feedstocks. National strategies of industrialized countries are being developed which identify microbial technology as a substantial factor in the attainment of industrial and economic goals. Although extremely promising microbial technology is not a quick fix and its application will only arise as a result of systematic programme of research and development. Such programme requires a broad base of disciplinary underpinning in molecular biology, genetics and bioengineering. The development of expertise of this kind in the tertiary educational institutions is the essential starting point. It should be developed by appropriate programmes and networking systems.

Biosynthesis of monensins A and B: the role of isoleucine.

Isoleucine added to the cultivation medium of Streptomyces cinnamonensis C-100-5 induced a relative increase of the production of monensin B at the expense of monensin A. U-14C-Isoleucine was found not to be a specific monensin B precursor. The incorporation of 1-13C-2-methylbutyrate into monensins A and B showed the label to be evenly incorporated in both products at carbon atoms originating from C(1) of propionate. In regulatory mutants insensitive to 2-amino-3-chlorobutyrate isoleucine influenced the production of monensins only slightly but strains resistant to 2-aminobutyrate and norleucine decreased their total production by 2-12% in the presence of isoleucine which was associated with a decrease of monensin A content by 14-52%. The inhibitory effect of isoleucine on the biosynthesis of valine, a specific precursor of the butyrate unit of monensin A, is discussed.

New bacteriophage-like particles in Corynebacterium glutamicum.

Three new phage-like particles (CG1, CG2, and CGK1) were isolated from Corynebacterium glutamicum CBII. Particles CG1 and CG2 are DNA phages with long, noncontractile tails, CGK1 is a killer particle according to electron microscopy. A heat-stable low-molecular-weight bacteriocidal substance affecting various coryneform bacteria was observed to be joined to the killer particle CGK1.

Isolation and characterization of the pMI10 plasmid from Bacillus subtilis, an alpha-amylase producer.

The plasmid DNA pMI10 (5310 bp) was isolated from the alpha-amylase producing strain B. subtilis A18. Thirteen restriction endonucleases were used to digest pMI10 DNA and the restriction map of pMI10 DNA was constructed by mapping PstI (1), HindII (2), BglI (2), BspRI (3) and HindIII (3) sites.

Fermentation production of L-homoserine by Corynebacterium sp. and its possible use in the preparation of threonine and lysine.

A mutant Corynebacterium sp. requiring threonine and cultivated for 3 d in a medium containing 15% sucrose, 8% corn-steep and 50 micrograms biotin per litre accumulated 14.5 g L-homoserine per litre. The possibility of fermenting the homoserine obtained for threonine and lysine production was investigated.

Effect of precursors on biosynthesis of monensins A and B.

Precursors of monensins (acetate, propionate, butyrate, isobutyrate) affect the total production and the relative proportion of monensins A and B. Addition of propionate into the fermentation medium causes a prevalence of monensin B whereas butyrate and isobutyrate stimulate the production of monensin A and suppress the production of monensin B.

Improving the production of monensin by Streptomyces cinnamonensis.

The production of monensin by Streptomyces cinnamonensis was increased by genetic improvement of the strain and by modification of cultivation conditions. The selection of a suitable strain and optimization of the fermentation process (temperature, aeration, addition of esters of oleic acid) resulted in a 30 fold increase of the monensin production.

Hydrodynamics, mass transfer, and yeast culture performance of a column bioreactor with ejector.

A bubble column fitted with an ejector has been tested for its physical and biological performance. The axial diffusion coefficient of the liquid phase in the presence of electrolytes and ethanol was measured by a stimulus-response technique with subsequent evaluation by means of a diffusion model. In contrast to ordinary bubble columns, the coefficient of axial mixing is inversely dependent on the superficial air velocity. The liquid velocity acts in an opposite direction to the backmixing flow in the column. The measurement of volumetric oxygen transfer coefficient in the presence of electrolytes and ethanol was performed using a dynamic gassing-in method adapted for a column. The data were correlated with the superficial air and liquid velocities, total power input, and power for aeration and mixing; the economy coefficient of oxygen transfer was used for finding an optimum ratio of power for aeration and pumping. Growth experiments with Candida utilis on ethanol confirmed some of the above results. Biomass productivity of 2.5 g L(-1) h(-1) testifies about a good transfer capability of the column. Columns fitted with pneumatic and/or hydraulic energy input may be promising for aerobic fermentations considering their mass transfer and mixing characteristics.

Anaerobic degradation of cellulose and formation of methane.

The existing knowledge of anaerobic digestion of cellulose-containing wastes and methane formation is reviewed. Mutual relationships between the individual phases of this complex process and the mechanism of methane biosynthesis are discussed in three sections: (1) Non-methanogenic phase and digestion of cellulose; (2) methanogenic phase and methanogenesis; (3) mixed cultures and their advantages.

The extracellular system of beta-1,3-glucanases of Alternaria tenuissima and Aspergillus vesicolor.

During cultivation in a minimal medium with glucose Alternaria tenuissima and Aspergillus vesicolor produce constitutively alpha- and beta-glucanases. Fractions of beta-1,3-glucanases exhibiting affinity for laminarin were separated by means of gel filtration chromatography. Two neutral beta-1,3-glucanases with affinity for yeast glucan were isolated by affinity chromatography and further characterized.

Biosynthesis of L-lysine in Corynebacterium glutamicum on sucrose, ethanol and acetic acid.

Production of L-lysine was followed in two lysine-accumulating mutants of Corynebacterium glutamicum ATCC 13287 in media containing sucrose, ethanol, acetic acid or a mixture of acetic acid and ammonium or sodium acetate. It was found that acetate is the best substitution for sucrose.