Effect of hyperbaric helium on vitamin uptake and utilization by micro-organisms.

Growth responses under hyperbaric helium of various procaryotic micro-organisms to graded levels of six water-soluble vitamins were measured. Vitamins included: thiamin, riboflavin, niacin, pantothenic acid, biotin, and folic acid (folacin). Growth response of each organism under hyperbaric helium was compared with that under 80% He-20% O2 and other He-O2 gas mixtures at atmospheric pressure, and with response in air at atmospheric pressure. For five of the six vitamins, no differences in response were observed. Growth response of Streptococcus faecalis to growth-limiting concentrations of folic acid was depressed during cultivation under He-O2 at 69 ATA. It is concluded that growth response of the organism is repressed by hyperbaric helium as a result of interference with uptake or utilization of the vitamin.