Physiological studies of subtropical mangrove thraustochytrids

Six thraustochytrids (Schizochytrium sp. KF-1, Schizochytrium mangrovei KF-2, KF-7, KF-12, Thraustochytrium striatum KF-9 and Ulkenia KF-13), isolated from fallen. senescent leaves of the mangrove tree Kandelia candel in Hong Kong, were identified and characterised in pine pollen seawater culture. Yeast extract peptone glucose seawater broth was used for growth studies. The pH range for growth was from 4 to 9 with optima from 4 to 7 for Schizochytrium species (KF- 1, 2, 7, 12) and 5 to 6 for Thraustochytrium striatum KF-9 and Ulkenia sp. KF-13. Temperature and salinity optima for isolates KF-2 and KF-7 were at 25degreesC and from 22.5-30 parts per thousand. respectively while isolate KF-12 had a temperature optimum from 20-25degreesC and salinity optima from 7.5-30parts per thousand. Thraustochytrium striatum KF-9 and Ulkenia sp. KF-13 showed strong growth at 25degreesC and 15-30parts per thousand.