Motoyoshi Hongo

Bacteriophages of the genus Clostridium.

Publisher Summary This chapter describes the properties and morphologies of phages that infect the industrially important clostridia, together with the nature of the damage and measures of control against phage contamination. The chapter also includes information about the well-known phages and phagelike particles of C. sporogenes, C. botulinum, and C. perfringens. One of the assays used for the phages of acetone-butanol-producing clostridia—is the modified double-layer method. In this method, a mixture of bacteria and phages is added to the bottom layer, covered with anaerobic agar medium containing sodium thioglycolate, and then incubated using the same procedure as for the cultivation of aerobes. The growth of phages is best under conditions which are good for the growth of the host organisms. In the case of C. botulinum and C. tetani, the plaque formation by phage infection is more difficult compared with C. sporogenes, C. perfringens, or C. saccharoperbutylacetonicum, because—the former species do not produce an even lawn on the agar plates.

Continuous production of acetic acid by electrodialysis bioprocess with a computerized control of fed batch culture

The technique of electrodialysis bioprocess, in which acetic acid is continuously removed from the reaction mixture, was applied to the production of acetic acid by Acetobacter aceti. The continuous supply of ethanol and concentrated nutrient solution to the reaction mixture allowed the production of acetic acid to continue for 30 d, while production continued for only 2 d without the electrodialysis system, with or without pH control. During electrodialysis bioprocess, 2221.9 g of acetic acid was produced from 1991.6 g of ethanol during the course of a single culture run of 30 d. The maximum rate of production of acetic acid obtained by electrodialysis bioprocess under the improved electrodialysis conditions was 5.5 g h−1, which was about 1.7 times higher than the rates obtained by bioprocesses without the electrodialysis system. The improvement in the rate of production and yield of acetic acid resulted from the alleviation of the inhibitory effect, on metabolism of the microbe, of the acetic acid that is produced, by maintaining a favorable pH and a low level of acetic acid in the reaction mixture by electrodialysis.

Morphological Changes during Conversion of Clostridium saccharoperbutylacetonicum to Protoplasts by Sucrose-Induced Autolysis

When exponentially growing cells of Clostridium saccharoperbutylacetonicum (ATCC 13564) were exposed to hypertonic concentrations of sucrose (0.3–0.5 M), rapid degradation of the cell wall occurred (sucrose‐induced autolysis). The morphological changes from the original rod‐shaped cells to protoplasts during the sucrose‐induced autolysis were investigated by phase contrast and electron microscopy. When the cells were autolysed in the sucrose solution (0.35 M), each cell began to swell at the middle or at one pole and then formed a small bulb at the swollen part. The bulb consisted of the cytoplasm which was enveloped by the plasma membrane and extruded from the small gap produced by the degradation of the cell wall. The bulb gradually enlarged as lysis progressed, and finally became a protoplast which had no cell wall. The large pre‐division cell frequently formed the bulb at the middle (septal site), while the small post‐division cell formed the bulb at the pole.

Bacteriophages of Clostridium saccharoperbutylacetonicum :Part XV. Mechanism of Inactivation of HM 2 Phage by Monovalent Cation

The inactivating action of monovalent cation (Na+) and the stabilizing action of divalent cation (Mg2+) on phage were studied using HM 2 phage (group I) of Clostridium saccharoperbutylacetonicum.The maximum rate of the phage inactivation occured at 0.1 m Na+. However, the serum-brocking power (SBP) of phage protein decreased with increasing the concentration of Na+. The inactivation of the phage by Na+ was associated with alteration of its sedimentation rate (s20,w), the release of its DNA, and denaturation of its protein. These facts indicate that Na+ causes the destructions of the structures of phage protein and DNA-protein complex. The action of Na+ on the phage could be illustrated by the salting-in and salting-out effects of protein of the phage by Na+.

Bacteriophages of Clostridium saccharoperbutylacetonicum: Part IV. Serological Characteristics of the Twelve HM-Phages

Antiphage sera were produced in rabbits against the HM-phages of Clostridium saccharoperbutylacetonicum; on the basis of cross-neutralization experiments with homologous and heterologous antisera, the twelve HM-phages were classified into three serological groups, termed I, II and III. Group I contained seven phages, i.e., HM 1, HM 2, HM 8, HM 9, HM 10, HM 11 and HM 12. Group II contained four phages, i.e., HM 3, HM 4, HM 5 and HM 6, and group III one phage, i.e., HM 7. This classification was in accord with morphological one that was reported in the preceding paper. By using the K value of antisera, the degree of serological relatedness among the phages within groups I and II was demonstrated. On the bases of serological similarities and of dissimilarities in host-rang specificity, the phages of groups I and II are considered as host range mutants derived from an identical ancestor, HM 1 and HM 3, respectively.

Studies on Oxidation-Reduction Potentials (ORP) of Microbial Cultures: Part I. l-Glutamic Acid Fermentation

At maximum production of l-glutamic acid, the oxidation-reduction potential of the culture broth in l-glutamic acid fermentation showed a stable value of 9.0 to 9.6 as rH value. When biotin concentration in the medium was high (40γ/liter), the production of l-glutamic acid decreased, and the rH was 8.0 and it was out of accordance with that of the control (biotin-poor; 2γ/liter). Under “less-aerobic” conditions, its rH rose to 10.4.From these results, it was concluded that the rH during maximum production of l-glutamic acid showed a stable value affected actively by the redox system, l-glutamic acid/α-ketoglutaric acid and

Bacteriophages of Clostridium saccharoperbutylacetonicum :Part XIII. Properties of HM 2 Phage Inactivated by DNase and the Tail of HM 2 Phage

To understand the mechanism of inactivation of HM 2 phage by DNase, studies were made on the properties of the inactivated phage, the structure of the intact and inactivated phages and the properties of the tail.HM 2 phage inactivated by DNase still retained the unique and large protein structure which combined fully with anti-HM 2 phage serum. According to electron microscopic observation, DNase-inactivated HM 2 phage looked empty and retained its tail surrounded with appendages. Ultracentrifugal analysis indicated that DNase-inactivated phage became a low molecular weight material after DNA had been extruded. The tail of the ghost retained normal ability to attach to its host bacteria, Cl. saccharoperbutylacetonicum N1-4. The tail of HM 2 phage does not have killing and lysing ability.From these results, it is concluded that the inactivation of HM 2 phage by DNase is not due to the damage of the coat protein and tail structure, but due to the damage of DNA itself.