Vitamin Sea: a review of the role of vitamins in marine biogeochemistry

A review by Sanudo-Wilhelmy et al. (2014) discusses the roles of soluble B vitamins in marine biogeochemistry, drawing upon a range of peer-reviewed literature. This blog aims to summarise the key points of this paper, especially those which are most relevant the material covered in the module.

Vitamins are small organic molecules that are required in both primary and secondary metabolism throughout all domains of life. Vitamins are vital for life and the name originates from “vital amine” (Funk, 1912) as it was initially believed that all vitamins were amines (but this was later proved not to be true). Vitamins are grouped by their solubility; B vitamins have several hydroxyl groups, meaning that they are soluble in water. Vitamins are commonly required growth factors and coenzymes for intermediary metabolism and have a role in many important metabolic pathways (Madigan & Martinko, 2005).

B vitamins have a central metabolic role in both marine phytoplankton and bacteria. Phytoplankton dynamics, particularly the succession of species, are greatly influenced by the availability of essential B vitamins and the different species-specific requirements for those growth factors. According to Carlucci & Bowes (1970a), some phytoplankton species excrete extracellular B vitamins and it was found that dissolved vitamins in high concentrations are linked to high phytoplankton biomass. The growth of certain organisms is influenced by other organisms that produce their required growth factors. Dominant phytoplankton species are affected by the depletion or enrichment of various B vitamins depending on their specific growth requirements. This is apparent in algal blooms; species-specific requirements cause species to flourish but this will deplete the water of a certain vitamin, allowing for the enrichment of a different vitamin and favouring the algal species with a suitable vitamin specifity to bloom (Provasoli, 1963).  

The study of B vitamins is important as many marine algae require them for growth (Provasoli & Carlucci, 1974). B vitamin auxotrophy (the inability of an organism to synthesize vitamin B which is required for its growth) was found to be common amongst phytoplankton and bacteria taxa (Croft et al., 2006). There is a nutritional relationship between auxotrophs and vitamin producers (Carlucci & Bowes, 1970b). Many eukaryotic phytoplankton cannot synthesize vitamin B12 from scratch which has lead to 70% of species becoming dependent on vitamin B12 being present in their environment. However, some species have overcome this limitation by adapting to use alternative enzymes. Vitamin auxotrophy in prokaryotes can be determined by testing for the presence or absence of vitamin synthesis pathways. Koch et al. (2012) noted that marine bacteria have to compete with the other organisms in their environment for the vitamins they require. A common misconception is that vitamins are only produced by prokaryotes, but vitamin-producing and consuming bacteria and algae are also present in the ocean.

This paper also looks at the distribution of vitamins throughout the oceans. Vitamin B12 was found in the highest concentrations in coastal waters and the lowest in open-ocean. The dissolved B12 was found to be highest at intermediate depth but was lower above and below. Sanudo-Wilhelmy et al. (2012) indicated that the distribution and concentration of vitamins is site specific and independent of each other. The cause of vitamin depletion has yet to be identified but it appears that vitamins are degraded by rise in water temperature and solar radiation (Carlucci et al., 1969); this could mean that climate change could reduce vitamin concentrations in the ocean.

Despite this comprehensive review which has compiled a lot of research regarding the current knowledge o f B vitamins in the ocean, there are still a lot of areas for expanded research. However, this will require improved methods according to the authors. A topic of particular interest to me is with regards to how the increasing sea temperatures will effect vitamin distributions on a global scale and the species that simply cannot grow or survive without these necessary growth factors.

Reviewed paper:

Sañudo-Wilhelmy, S., Gómez-Consarnau, L., Suffridge, C., & Webb, E. (2014). The Role of B Vitamins in Marine Biogeochemistry. Annual Review Of Marine Science, 6(1), 339-367. http://dx.doi.org/10.1146/annurev-marine-120710-100912

Other cited papers:

CarlucciAF,SilbernagelSB.1969a.Effectofvitaminconcentrationsongrowthanddevelopmentofvitaminrequiring algae. J. Phycol. 5:64–67

CarlucciAF,BowesPM.1970a.ProductionofvitaminB12,thiamine,andbiotinbyphytoplankton.J. Phycol. 6:351–57

Carlucci AF, Bowes PM. 1970b. Vitamin production and utilization by phytoplankton in mixed culture. J. Phycol. 6:393–400

Croft M, Warren MJ, Smith AG. 2006. Algae need their vitamins. Eukaryot. Cell 5:1175–8

Funk C. 1912. The etiology of the deficiency diseases. J. State Med. 20:341–68

Koch F, Hatten-Lehmann TK, Goleski JA, Sa˜nudo-Wilhelmy SA, Fisher NS, Gobler CJ. 2012. Vitamin B1 and B12 uptake and cycling by plankton communities in coastal ecosystems. Front. Microbiol. 3:363

MadiganMT,MartinkoJM,eds.2005.BrockBiologyofMicroorganisms.UpperSaddleRiver,NJ:PrenticeHall. 11th ed.

ProvasoliL.1963.Organicregulationofphytoplanktonfertility.InTheSea,Vol.2,CompositionofSea-Water, Comparative and Descriptive Oceanography, ed. MH Hill, pp. 165–219. New York: Interscience

ProvasoliL,CarlucciAF.1974.Vitaminsandgrowthregulators.InAlgalPhysiologyandBiochemistry,ed.WDP Steward, pp. 741–87. Berkeley: Univ. Calif. Press

Sanudo-Wilhelmy SA, Cutter LS, Durazo R, Smail EA, Gomez-Consarnau L, etal.2012.MultipleB-vitamin depletion in large areas of the coastal ocean. Proc. Natl. Acad. Sci. USA 109:14041–45