The influence of pH, temperature and organic matter on the degradation of the lignin-cellulose complex of coconut fibres was studied. Many fungi (deuteromycetes and ascomycetes) and bacteria were isolated from partly decayed coir. The decomposition of the coconut fibres by these isolates was estimated, imitating field conditions. Some fungi of the genera tested were able to partly decompose the coconut fibres after long incubation periods. However, the quick and total decay of the coir wrapper around drain pipes seems to be caused by basidiomycetes only.
An NAD-linked 2-carboxybenzaldehyde dehydrogenase which catalyzes the conversion of 2-carboxybenzaldehyde to o-phthalate was isolated and purified about 130-fold from the cell extract of Alcaligenes faecalis AFK2 which was grown on phenanthrene. The purified enzyme had a molecular weight of about 160, 000, and consisted of four molecules of a single kind of polypeptide having a molecular weight of 40, 000. It showed high specificity for 2-carboxybenzaldehyde as its substrate and for NAD as its electron acceptor. The Km values for the substrate and NAD were 5.4×10-5 and 1.4×10-4M, respectively. Because of the increase in the enzyme level by the growth on phenanthrene, the enzyme was inducible, suggesting its responsibility for the degradation of phenanthrene in Alcaligenes faecalis AFK2.
Sulfate-reducing bacteria isolated from sewage digestor fluids and other natural habitats were characterized by their morphological, physiological and chemical properties. Strains (A-1 and B-1) isolated from drains were identified as Desulfovibrio desulfricans. On the other hand, isolates (F241, 1111 and KOKU) from sewage digestor fluids did not fully coincide with any sulfate-reducing bacteria hitherto described in several features of carbon sources utilization and nutritional requirements. They were thought to be atypical D. desulfricans and were named D. desulfricans subsp. stercorivorus nov. subsp. The cellular fatty acid composition of the isolates was analyzed and used effectively for the identification thereof.
The effect of superoxide anion (O2-) on killing of cells was studied. E. coli was killed by a non-enzymatical O2--generating system, i.e. a phenazine methosulfate (PMS)-NADH system. Both polA and recA repair-deficient mutants were more sensitive to O2- than wild type cells. Furthermore, using the polA mutant strain, it was clearly shown that incubation in growing medium increased survival, indicating the involvement of a rec-dependent repair system. It was concluded that the direct cause of cell death induced by O2- was DNA damage. When a scavenger of the active oxygen, such as superoxide dismutase (SOD) or catalase, was present in the reaction buffer during O2- treatment, the survival of cells increased. Of especial note, cells were completely protected by addition of catalase. It was suggested that H2O2 produced from O2- and H2O was a molecule more toxic to E. coli cells than the O2- itself in this system. When SOD and catalase were induced inside cells by adding methyl-viologen in the medium, a protective effect against O2- appeared. Cells treated with methyl-viologen were also resistant, although slightly, to aerobic γ-ray irradiation, suggesting that the scavenger of active oxygen in cells was partly responsible for protection against γ-ray irradiation. It is deduced that O2- and/or H2O2 generated in cells may be one of the causes of cell damage by aerobic γ-ray irradiation.
A ribonucleoside 2′, 3′-cyclic phosphodiesterase (cyclic phosphodiesterase) having 3′-nucleotidase activity was purified from the cell-free extract of Bacillus subtilis var. amyloliquefacus, and its enzymatic properties were examined. The molecular weight was approximately 74, 000. The enzyme was highly specific for ribonucleoside 2′, 3′-cyclic monophosphate (2′, 3′-cyclic mononucleotide), and ribonucleoside 3′-monophosphate (3′-mononucleotide), and also hydrolyzed bis-p-nitrophenyl phosphate (bis-p-NPP) but at a rate much slower than that of 3′-mononucleotide. Both cyclic phosphodiesterase and 3′-nucleotidase activities had an optimum pH of about 6.7, and phosphodiesterase activity against bis-p-NPP indicated a relatively sharp pH optimum at 5.0. Only phosphodiesterase activity against bis p-NPP was greatly activated by Co2+, but both cyclic phosphodiesterase and 3′-nucleotidase activities were inhibited. However, Co2+ had an effect of protecting the enzyme against heat inactivation. 3′-Nucleotidase activity was not affected by EDTA, while phosphodiesterase activities against both 2′, 3′-cyclic mononucleotide and bis-p-NPP were greatly inhibited. The enzyme hydrolyzed 3′-AMP with Km 0.046mM and Vmax 1, 585μmol per hr per mg protein, bis-p-NPP with Km 0.16mM and Vmax 233μmol per hr per mg protein.
A strain of Pseudomonas sp. was isolated from activated sludge, growing on a mineral medium with benzylpenicillin as the sole carbon source. During growth the phenylacetate side chain was degraded and utilized. The nucleus molecule of the antibiotic, 6-aminopenicillanic acid, was not used but hydrolysed to penicic acid. Cell-free extracts contained β-lactamase and penicillin acylase activities.