VITAMIN B12, THIAMINE, AND BIOTIN CONTENTS OF MARINE PHYTOPLANKTON1

Abstract

SUMMARYAn extraction procedure was developed for determining vitamin B12, thiamine, and biotin contents of marine phytoplankton. Phytoplankters were collected either by centrifugation or by retention on a glass fiber filter, then heated at 100 C for I hr in 100 ml of vitamin‐free seawater acidified to pH 3.5 with HCl. The extract, after debris removal, was filter‐sterilized and analyzed, for vitamin B12, thiamine, and biotin with standard vitamin assay procedures.The vitamin contents of haeodactylum tricornutum, Skeletonema costatum, Stephanopyxis turris, and occolithus liuxleyi were determined during growth in batch cultures. P. tricornutum (non‐vitamin requirer) growing in aerated cultures contained 0.29–0.96 ng B12, 5–15 ng thiamine, and 0.45–1.70 ng biotin/mg C. Under similar conditions S. costatum (B12‐requirer) contained about 0.06 ng B12, 5–36 ng thiamine, and 0.16–2.10 ng biotin/mg C. The concentrations of vitamin were generally similar during some portion of the growth curve, eg, logarithmic growth.The vitamin B12, content of S. costatum growing under nonaerated conditions decreased when medium B12, was reduced. The biotin content did not change when medium B12 was decreased.The thiamine content per unit weight of C. huxleyi (thiamine‐requirer) growing with either 10 or 120 ng/liter thiamine decreased under both medium concentrations, indicating no net synthesis of the vitamin.