No abstract

No abstract

The decomposition of silicate minerals and related substances by fungi has been investigated using two techniques: (a) the incorporation of the mineral material in agar medium, when its breakdown is indicated by the formation of clear zones round the fungal growth; (b) the determination of the metal and silicate ions, derived from the insoluble materials and brought into solution as a result of fungal activity in liquid medium. Strains of fungi which produced citric and/or oxalic acid proved to be effective in decomposing certain natural silicates, while an oxalic acid-producing strain also released metallic ions and silica from rocks and soils. A possible role of fungi in biological weathering is discussed.

No abstract

SUMMARY: A study of the mechanism of breakdown of w-phenyl-substituted fatty acids by Nocardia opaca has been made. Acids with an odd number of carbon atoms in the side chain (phenylpropionic, phenylvaleric and phenylheptylic acids) were converted to benzoic acid, and cinnamic acid was an intermediate. o-Hydroxyphenylacetic acid was identified as a common product when acids with an even number of carbon atoms (phenylacetic, phenylbutyric, phenylcaproic and phenylcaprylic) were used. This evidence supports /3-oxidation as a mechanism of breakdown of short chain fatty acids by N . opaca.It was shown that Nocardia opaca would grow on a wide range of saturated aliphatic fatty acids as sole carbon and energy source (Webley, 1954), and that washed suspensions of glucose grown cells gave enhanced oxygen uptake in the presence of these acids (Webley & DeKock, 1952). The mechanism by which acid-fast organisms attack fatty acids is, a t present, unknown. In the present work the metabolism of o-phenyl-substituted fatty acids by N . opaca has been studied and the results are in favour of P-oxidation of the short chain fatty acids by this organism. Growth experiments, manometric measurements, spectrochemistry and chromatography have been employed. METHODS