Studies on B Vitamins in Relation to Productivity of the Bahia Fosforescente, Puerto Rico

The Bahia Fosforescente of Puerto Rico is luminescent because of a continuing bloom of dinoflagellates, a group including species known to be dependent for growth upon exogenous sources of B vitamins. Vitamin B₁₂ in suspended solids of the bay ranged from 430 to 2930 mγ/gm. The ratio of B₁₂ in suspended solids, to B₁₂, in solution, was calculated to be about 2.5. Of the total B₁₂ activity, determined with a mutant E. coli, from 7 to 23 per cent appeared to be cyanocobalamine, as indicated by Ochromonas assay. Averaged data from five selected stations in July of 1957, gave vitamin values in mγ/gm. of dried sediments as follows: B₁₂, 280; biotin, 7; B₁, 73. The calculated ratio of about 40:1:10 for these three vitamins is at variance with the estimated ratio of 1:1:800 for their proportions which would allow half maximum growth of vitamin-requiring microorganisms. It may be concluded that while B₁₂ appears to be present in the bay sediments in relative excess, vitamin B₁ is probably a limiting factor for development of benthic populations. Data obtained for ten segments of a mud core suggest that B vitamins decrease with increasing depth and age of sediments. Large populations of both aerobic and anaerobic bacteria were found in various bottom sediments, consisting of fine ooze, shell and siliceous sands, and mangrove peat. Bacteria and actinomycetes in the drainage basin and bacteria in the marine water and sediments were observed to produce vitamin B₁₂. Although some B₁₂ is undoubtedly contributed periodically from the watershed, synthesis of this vitamin occurs in the marine environment at significant physiological levels.