Organic acid production by Basidiomycetes. 3. Cultural conditions for L-malic acid production

Cultural conditions were examined for the purpose of increasing yields of l-malic acid by the Basidiomycetes Schizophyllum commune and Merulius tremellosus, which have the ability to produce this acid as a main product in CaCO(3)-containing medium in shaken culture. The most favorable nitrogen sources selected were 0.3% (NH(4))(2)SO(4) and 0.18% NH(4)Cl. Effective combinations of inorganic salts in the medium were 0.1% KH(2)PO(4), 0.05% MgSO(4).7H(2)O, and 0.05% KCl, and suitable concentrations of glucose were 5 to 10%. Several nonionic surface-active agents promoted the filamentous mycelial growth of these strains and increased acid production. In particular, Tween 80 in 0.3% concentration markedly stimulated malic acid production by S. commune, and yields greater than 50% based on available glucose, were obtained after 10 to 14 days. Acid production by M. tremellosus was stimulated most with 0.5% Carbowax 4000 (polyethylene glycol), and the resultant yields were more than 40%.     

Acid production bySc. thermophilus

Summary The calculation based on the idea formulated as the Law of Diminishing Returns has here been applied to the development ofSc. thermophilus in milk-cultures during the phase of diminishing growth rate. The values calculated correspond fairly well with the data found in the experiment. An application of this method is given in the calculation of the relation between the acid production per cell (diplococci) per hour and the generation time. It is shown, that a quick multiplication corresponds to a high acid production and inversely a long generation time gives a small acid production. The relation between these quantities enables us to account for the rapid acidification in yoghurt. It also enables us to calculate the acid production in yoghurt by the cocci and the rods from the experimental data. By making this calculation we could prove that in the first stage the cocci are the acid producers. In the second stage the rods keep producing acid whereas the growth of cocci is checked by the lactic acid which has then for the greater part been produced by themselves. The author is now Director of the Government Dairy College at Bolsward.     

Heat production non-myelinated nerves.

Experiments with the C fibres of the rabbit vagus nerve have established that heat is evolved during the depolarizing phase of the action potential and is absorbed during the repolarizing phase. Subsequent studies using the pike olfactory nerve indicate that the heat production begins at a high rate very early in the depolarizing phase and is completed in advance of the peak of the spike. This would be expected if the heat arised from the energy released by the discharge of the membrane capacitance which varies as the square of the membrane potential; but estimates of the stored energy fall short of the observed heat production by a factor of two or three times. The prominent cooling phase suggests that a substantial part of the heat may arise from an entropy change. Such an entropy change would be expected to result from the change in the electrical stress in the dielectric of the membrane capacitance, and may thus be manifestation of reversible changes in the molecular architecture of the insulating matrix of the membrane.     

Pneumocystis carinii--animal production perspective.

Pneumocystis carinii is an important cause of pneumonia in immunocompromised human patients. The organism is also found as a saprophyte in the lungs of many species of animals. Animal models have been used as a source of P. carinii organisms for study of the disease. The rat model has been especially useful. Initially, the infection was latent in most colonies, and P. carinii pneumonia readily developed when animals were immunosuppressed. Today, many barrier raised rodent colonies are free of adventitious viruses, bacteria, Mycoplasma sp., and parasites, including P. carinii. Variability is now seen in the rat model. The use of cultured organisms to experimentally infect rats and mice prior to immunosuppression has met the need for some investigators, however, latent-infected, barrier-raised and isolator-raised rodents are still required. Colonies specifically infected with P. carinii can provide latent-infected animals and are better protected from potentially interfering organisms than barrier-raised animals. The development of these colonies is feasible as investigators and animal producers work together to define and develop this resource.     

Cutinase production byStreptomyces spp.

Forty-fiveStreptomyces strains, including representatives of the plant pathogensS. acidiscabies, S. scabies, andS. ipomoea, were screened for ability to produce enzymes (cutinases) capable of hydrolyzing the insoluble plant biopolyester cutin. Initially, all strains were tested for production of extracellular esterase in liquid shake (250 rpm) cultures at room temperature in defined (glycerol-asparagine) or complex (tryptone-yeast extract with or without addition of mannitol) broth media supplemented with either tomato or apple cutin. Esterase activity was determined by a spectrophotometric assay utilizing the model substratep-nitrophenyl butyrate. Of the five strains exhibiting highest esterase activity, four (S. acidiscabies ATCC 49003,S. scabies ATCC 15485 and IMRU 3018, andS. badius ATCC 19888) were confirmed to produce enzymes with cutin-degrading activity (cutinases). Confirmation of extracellular cutinase production was accomplished by use of a new high-performance liquid chromatography method for separation and quantification of released cutin monomers. Monomer identification was confirmed by GC/MS analyses. Cutinase production was induced 2- to 17-fold by inclusion of cutin in the media. To our knowledge this constitutes the first report of cutinase production byStreptomyces spp. other thanS. scabies.Reference to any brand or firm name does not constitute endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned.     

Methanol production by Mycobacterium smegmatis.

Mycobacterium smegmatis cells produce [3H]methanol when incubated with [methyl-3H]methionine. The methanol is derived from S-adenosylmethionine rather than methyltetrahydrofolate. M. smegmatis cells carboxymethylate several proteins, and some of the methanol probably results from their demethylation, but most of the methanol may come from an unidentified component with a high gel mobility. Although methanol in the medium reached 19 microM, it was not incorporated into the methylated mannose polysaccharide, a lipid carrier in this organism.     

Plant-based production of xenogenic proteins.

Foreign protein production in transgenic plants has been successful, from the generation of transgenic plant lines to the marketing of purified proteins. Antigenic proteins from disease organisms, monoclonal antibodies raised against antigens of disease organisms, and proteins with industrial process applications have been produced and tested. For vaccines, clinical trials in humans and feeding trials in animals are in progress to demonstrate their efficacy. For industrial proteins, high expression and downstream processing efficiency are key concerns, with application and test market trials in progress.     

Ochratoxin production by Aspergillus species.

Ochratoxin production was tested in 172 strains representing species in sections Fumigati, Circumdati, Candidi, and Wentii of the genus Aspergillus by an immunochemical method using a monoclonal antibody preparation against ochratoxin A. Ochratoxin A was detected in Aspergillus ochraceus, A. alliaceus, A. sclerotiorum, A. sulphureus, A. albertensis, A. auricomus, and A. wentii strains. This is the first report of production of ochratoxins in the latter three species. Ochratoxin production by these species was confirmed by high-performance thin-layer chromatography and by high-performance liquid chromatography. The chemical methods also indicated the production of ochratoxin B by all of the Aspergillus strains mentioned above.     

Siderophore production by Aeromonas salmonicida.

Growth under conditions of iron-restriction and the production of siderophores was examined in 21 typical and 14 atypical strains of Aeromonas salmonicida. With the exception of one atypical strain, all strains grew and multiplied in the presence of the high-affinity iron chelators ethylenediamine di(o-hydroxyphenylacetic acid), alpha, alpha'-dipyridyl or transferrin. Chrome azurol S agar was used to screen bacterial strains growing under these conditions for the production of siderophores. Siderophore production was detected only in the typical strains. Siderophores were also detected in the iron-restricted culture supernatants of typical strains. Siderophores were also detected in the iron-restricted culture supernatants of typical strains, where they were associated with an iron-binding activity. The siderophore was extracted from iron-restricted culture supernatant of one strain by adsorption onto an XAD-7 resin; it behaved as a 2,3-diphenol-catechol in several colorimetric assays. The results indicate that although both typical and atypical strains of A. salmonicida grow and multiply under conditions of iron-restriction, they use different iron-uptake mechanisms, siderophore-mediated and siderophore-independent, respectively. In cross-feeding assays, growth of typical strains was stimulated only by homologous iron-restricted supernatant, suggesting strain differences in the siderophore produced. However, one strain produced a culture supernatant with growth-stimulating activity for other typical and also atypical strains.