The Morphology of Nocardia opaca Waksman & Henrici (Proactinomyces opacus Jensen) when Grown on Hydrocarbons, Vegetable Oils, Fatty Acids and Related Substances
SUMMARY: Nocardia opaca Waksman & Henrici can use certain long chain saturated aliphatic hydrocarbons and many vegetable oils as sole carbon and energy source in presence of simple mineral salts. Long chain saturated aliphatic acids (e.g. myristic, palmitic and stearic) can similarly serve. The same general morphological development is obtained on all these compounds but the initial mycelial phase is more pronounced on oily substrates (particularly hydrocarbons) than on water soluble or insoluble solid substances. Granules are demonstrable inside the cells. These granules are more intensely stained with fat and polysaccharide reagents than the rest of the cell. Well-defined electron dense bodies are also observed which behave similarly to the 'mitochondria' described by Mudd, Winterscheid, DeLamater & Henderson (1951) in Mycobacterium thamno- pheos under intense electron bombardment. Webley & de Kock (1952) showed, by means of the Warburg technique, that the addition of certain long chain saturated aliphatic hydrocarbons, alcohols and acids to washed suspensions of Nocardia opaca grown on a glucose con- taining medium enhanced oxygen uptake. In the present paper a study has been made of the growth and morphology of this organism with these sub- stances as sole carbon and energy sources. The work was extended to include vegetable oils, some waxes and other related substances. METHODS Organism. Nocardia opaca strain Tls was used throughout (Webley & de Kock, 1952). Growth ezperiments were carried out in 2 02. screw-capped bottles containing 5 ml. medium. A mineral medium of the following composition was used throughout ( %, w/v) : NaNO,, 0-2 ; NaC1, 0.02 ; MgSO, . 7H20, 0.02 ; FeCl,, trace. The pH value of the solution was adjusted to 7.2. Curb? compounds used. For the oily substances 0.2 ml./bottle of each was used. For solid water-insoluble substances, a few flakes of each substance were added to the salt solution in the 2 02. bottles before autoclaving. Fatty acids were used as sodium or potassium salts. Thus the only carbon source, apart from atmospheric CO,, involved in the growth experiments, was the carbon compound added to the salt solution. Whenever possible highly purified chemicals were used, Inoculum. One or two drops of a thin suspension of Nocardia opaca in distilled water was used to inoculate each culture bottle, This suspension was