The growth of Sarcina lutea

✍ Scribed by Rubenstein, B. B.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1933
• Tongue: English
• Weight: 647 KB
• Volume: 3
• Category: Article
• ISSN: 0095-9898
• DOI: 10.1002/jcp.1030030207

✦ Synopsis

Before considering the growth of Sarcina lutea, it is advisable to define clearly the criteria of growth. The ordinary bacteriological method (counting of cells) implies that the growth of bacteria consists of a succession of fissions and that the resulting cells are uniform in size. Recent work from many laboratories, summarized ably by Henrici( 8), indicates that there is considerable change of size during the growth of many bacteria. This was quite conclusively demonstrated for organisms of the colon-typhoid group by the photomicrographic method of Bayne-Jones (1). Mere counting of cells is thus an insufficiently accurate measure of growth, if growth be defined as the increase in quantity of bacterial protoplasm.

Of the other methods that have been used to estimate the growth of bacteria (gravimetric, nephelometric, biochemical, volumetric, etc.), the volumetric method appears to be the most exact; this method, frequently controlled by cell counts, was used in the present work. The cells were centrifuged to constant volume at high speed in fine capillary tubes of constant bore. The height of the column of sediment was then measured accurately, and the volume of the cells was calculated. The measurement was corrected for the osmotic pressure of the medium, being reduced to the column in N/10 NaC1. I t was found that a cubic millimeter of sediment con-