Chapter VIII 



119 — 



Marine Bacteria 



as Achromohader jischeri. Johnson and Shunk also described Achromo- 

 bacter harveyi, which they isolated from marine materials. KLatz (1891) 

 isolated marine photogenic bacteria now known as Bacillus argenteo-phos- 

 phorescens, Bacillus cyaneo-phosphorescens , Bacterium smaragdinophosphor- 

 escens, Achromohader phosphoricum, A. phosphoreum, and A. luminosum. 

 Most of these are characterized by Bergey et al. (1939) who also list 

 Pseudomonas pierantonii, Vibrio pierantonii, Bacterium giardi, Micrococcus 

 phosphoreus, M. pfliigeri, and Photobaderium pflUgeri. In a comprehen- 

 sive resume of the literature and compilation of species, Dahlgren (191 5) 

 adds the following: Photohacterium balticum, Ph. cyaneum^ Ph. javanense 

 Ph. plymouthii, and B. phosphorescens gelidus, all of which were found in 

 sea water or associated with marine fish. Dahlgren regards many of the 

 afore-mentioned species as being synonymous. Bioluminescence is pre- 

 ponderantly a property of marine organisms (Harvey, 1940). 



The luminous marine bacteria studied by Johnson and Harvey (1938) 

 required sea water for maximum efficiency. Luminescence, as well as 

 respiration, fell off when sea water was diluted by more than 50 per cent 

 with fresh water. Below a concentration of 10 per cent sea water both 

 respiration and luminescence were irreversibly destroyed, and only a small 

 fraction of the cells remained viable. Doubling the salinity of sea water 

 by the addition of salts did not markedly affect luminescence, but further 

 increases in salinity were inimical to the respiration, luminescence, and 

 viabihty of marine photogenic bacteria. Isotonic salt or sugar solutions 

 were not so favorable as was natural sea water for the activity of the 

 bacteria. 



The physiological characteristics of various groups of marine bacteria 

 are discussed elsewhere in this volume. In the foregoing paragraphs only 

 a few of the distinctive physiological characteristics of marine bacteria, 

 as a class, have been compared with bacteria from other habitats. 



Salinity requirements: — The preference of marine bacteria for sea 

 water over either tap water or NaCl solution isotonic with sea water is 

 illustrated by the data in Table VIII on page 44. Plate counts of either 

 raw sea water or marine mud collected beyond the zone of land contam- 

 ination are invariably higher when the nutrient media are prepared with 

 sea water rather than with fresh water. Conversely, samples of sewage, 

 soil, fresh water, human excreta, etc., show many more colonies when 



Table XXXII. — Relative numbers of bacteria from marine and terrestrial sources which 

 developed on nutrient media prepared with different concentrations of sea water {from ZoBell 

 jg4ia): — 



Media 



inoculated 



^\^TH 



Raw sea water 

 Marine mud 

 San Diego Bay mud 

 Mission Bay mud 

 Mission Bay water 

 Sewage 

 Tap water 

 Inland soil 

 Mouth microflora 



Number 



OF 

 SAMPLES 



31 



18 



3 

 4 

 5 

 13 

 8 

 6 

 5 



Per cent of sea water in medium 



100 



100 



100 



100 



100 



13 



4 



15 



9 



75 



93 



89 



108 



107 



103 



27 



10 



23 



15 



average growth index 



9 



19 



114 



106 



97 

 100 

 100 

 100 

 100 



