The chrysomonads are a vast array of brown-pigmented fresh-water, soil, and marine flagellates. Colorless phagotrophic counterparts of several of the pigmented species are common in nature, e.g., Molzus and Oikomonus. The minimal nutritional requirements of 4 fresh-water strains belonging to 2 species are described here. No chrysomonad previously has been grown in chemically defined media. These strains ingest particulate food and are therefore animals (protozoa) and, being to some extent phototrophic, they are plants (algae) as well. They can live indefinitely in darkness or in light on high-molecular dissolved food, as well as in low-molecular chemically defined media. This extraordinary versatility, first thoroughly documented in the pioneering pure culture study of Pring~heirn,~ is accompanied by a remarkable tolerance of variations in media and exceedingly dense growth in appropriate media, including certain simple "synthetic" media [one cannot unambiguously call "synthetic" a medium containing cobalamin (vitamin Biz), whose complete structure is still to be ascertained]. This ease of cultivation-in which respect these chrysomonads contrast sharply with some of the planktonic chrysomonadslO-suggests that the biochemical basis of an intermeshed phagotrophy and phototrophy can profitably be investigated in them.PringsheimQ reviewed the scanty previous work. He demonstrated an active phagotrophy in the same strains on which the present paper is based: They ingested starch grains, oil droplets, casein particles, bacteria, and small algae -including each other. Glucose was utilized in the presence of complex natural materials such as peptone. Liver extracts were strikingly stimulatory. Dark growth was improved by aeration and paralleled that in light. Darkgrown individuals were pale. Cultures accumulated a water-soluble sepia or almost black substance which was also produced by pale growths in the dark.With chemically defined media-the subject of this paper-it should be possible to explore systematically their ability to utilize high-molecular sources of energy and carbon, nitrogen and amino acids, biotin, thiamine, and cobalamin.To identify the growth requirements of aerobic phototrophs, culture methods are needed which combine adequate illumination with freedom from significant chemical contaminations. Such considerations apply with special force to these chrysomonads. Growing densely, they need much illumination. Hence they were cultured in shallow layers of medium, and their sensitive response to certain widely-distributed growth factors such as biotin and cobalamin spurred the development of methods to minimize the confusion introduced by * This investigation was aided by grants from the Lederle Laboratories Division of the American Cyanamid Company, the Atomic Energy Commission [contract AT(30-1)-863] and the Rockefeller Foundition. We are indebted to Doctors E. G . Pringsheim and R. A. Lewin for the geuerdus gift of cultures and unpublished information. Doctor F. C. Bersworth of the Bersworth Chemical Comp...
SUMMARY : Colour mutants of the tomato pathogen, Coynebacterium michiganense, provided an opportunity to determine the nature of this micro-organism's pigments, and the effect of mutation and nutrition thereon. The major pigments of C. michiganense are carotenoids. The parent and mutant strains show distinct qualitative differences in pigment synthesis. The naturally occurring yellow parent type produces cryptoxanthin and lycopene. A pink mutant forms lycopene and spirilloxanthin, A red back-mutant produces only lycopene. An orange mutant synthesizes cryptoxanthin, /?-carotene and canthaxanthin. Carotenoids were not detected in the colourless mutants.Carotenoid synthesis in the yellow strain of C. rnichiganense is affected by thiamine in a manner similar to that previously described for C. poinsettiae: cryptoxanthin and lycopene are synthesized only at relatively high thiamine concentrations. The formation of lycopene, relative to spirilloxanthin, in the pink mutant is favoured by high thiamine concentrations. Similarly, the red strain forms appreciably more lycopene a t higher thiamine concentrations than at lower. The formation of carotenoids in the orange strain appears not to be influenced by external thiamine concentration, possibly because this culture synthesizes an excess of the vitamin. No other nutritional factor which was examined caused detectable alterations in colour of the cells.
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