Bacterial Counts on Commercial Raw Cotton from the U.S. Crop of 1980

A series of 143 commercial cotton fiber samples of widely varying grade from the 1980 U.S. crop was tested for bacterial content because of possible relevance of bacteria to byssinosis. Much sample-to-sample variation occurred in counts for total, gram-negative, and coliform bacteria, even among samples of the same or similar grade and geographical origin. Ratios of the three bacterial categories to each other within single samples also varied widely. Total bacteria ranged from 10,000 to 290,000,000 per gram of fiber..

Especially high counts were found in some spotted and tinged samples, but total bacterial numbers of more than a million per gram of fiber were encountered even in the better white grades. Bacterial numbers were not correlated with fiber pH. Most samples contained residual water-extractable materials capable of supporting addi tional bacterial growth. Bacterial counts on raw cotton fiber, as reported in the literature, were reviewed and found to be generally in the same range as those shown here.