Physiological requirements of two marine phycomycetes, Althornia crouchii and Ostracoblabe implexa

Growth of two marine phycomycetes isolated from diseased oyster shells was investigated. Both fungi were obligately marine and stenohaline, with optimum growth in 2·3–2·5% sodium chloride. Of the minor salts in an artificial sea-water medium, sodium bicarbonate produced the most significant stimulation of growth of Althornia crouchii. Both fungi grew best at 30 °C; there was no growth at 35°. Light inhibited the growth of the fungi. They grew well in natural or artificial sea water supplemented with yeast extract (1 g/l) and peptone (1 g/l). They did not grow if the concentrations of yeast extract and peptone were reduced to 0·02 g/l. A. crouchii produced normal sporangia and zoospores on glycogen, D(+)trehalose or cellobiose. The addition of sodium malate also permitted good growth, but without zoospore production. Ostracoblabe implexa was stimulated by the simultaneous addition of sodium malate, aspartic acid and sodium glutamate. Most other carbohydrates and fatty acids tested either did not support growth or were inhibitory. Inorganic nitrogen sources tested did not support growth of A. crouchii