Date of Award

Spring 1958

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)




The appearance of crystals during growth of bacterial cultures is probably not a rare occurrence although it is infrequently mentioned in microbiological literature. Many textbooks refer to "bacterial calculi" as artefacts representing accretions of salts due to drying of media, (eg., Lamanna and Mallette, 1953). However, Scudder (1926) observed magnesium ammonium phosphate crystals in cultures of various species of organisms and concluded that their appearance was dependent upon rapid alkalinization of the medium, proteolytic activity in the culture, water of condensation, and a semi-solid state of the medium. These observations were confirmed later by Huddleson and Winters (1927) and by Bartels (1950). Calcium carbonate crystals have also been observed by Hewitt (1947) in cultures growing on high calcium ion content media and attributed to carbohydrate fermentation with accompanying carbon dioxide which combined with the calcium ions. Intracellular protein crystals were found by Hannay and Fitz-James (1955) in a strain of Bacillus thuringiensis (Berliner) but no information was given regarding their origin. The production of visible crystals of magnesium ammonium phosphate within growing bacterial colonies may present a problem because of interference with cell-viability and make maintenance of stock cultures more difficult, (Huddleson and Winter, 1927). It may also be worth mentioning that oral actinomycetes from saliva produce the same type crystals and this has been associated with formation of dental calculi. (Bartels, 1950). A problem of more basic interest, however, is the mechanism of production and its relationship to fundamental cellular physiology from the microbiological aspect, for although Scudder (1926) noted the basicconditions necessary for production of these crystals by bacteria, the actual process remains obscure. A study of this problem has, therefore, been made using two genetically related strains of M. pyogenes (var. aureus), one of which produces crystals and the other does not.