Marion E. Simpson

The Influence of Weathering Prior to Harvest on Certain Properties of Cotton Fibers

Most of the.commercial cotton fiber produced in the United States is subjected to a period of from one to many weeks of exposure to the weather before it is harvested from the plant. Such weathering has been shown in prior work to be a cause of changes in the wax on the fiber [19], in the fibers swelling behavior in alkali [22]. and, under humid conditions, in the pH of water extracts of the fiber [21]. Subsequent investigation now has revealed that a number of other fiber properties also may undergo change during preharvest weathering. These properties include moisture regain at constant relative humidity, dye absorption, content of water-soluble reducing substances, browning tendency, rate of wetting in a water-alcohol mixture, length, strength, and susceptibility to enzymatic decomposition. As might have been expected, the X-ray angle, as defined by Berkley and co-workers [4], showed little if any alteration. Several of the fiber properties which change during weathering have been measured on commercial fiber samples and the results found to show a relationship to the grade of the fiber. Further work is in progress to analyze the nature of the above fiber property changes and to detect other changes which may occur. A rapid and practical test for measuring the water-soluble copper-reducing constituents in raw cotton fiber is described.

Degree of Polymerization, Spiral Structure, and Strength of Cotton Fiber

Cotton fiber from bolls collected on opening and dried in the laboratory without exposure to direct sunlight were tested for the following fiber properties: fiber length, fineness, strength, spiral structure, and degree of polymerization (D.P.). When these individual properties were each correlated with the Pressley strength index in simple correlations, the spiral structure and Pressley strength index gave the highest r values, and the degree of polymerization and Pressley index the second highest. For variety effects, the D.P. and Pressley index gave a higher coefficient of correlation than the spiral structure and Pressley index. Significant r values were obtained between fineness and Pressley index for total and variety effects, between fineness and D.P. for all effects, and between spiral structure and D.P. for all effects. Further more, a significant r value was found when fiber length was correlated with chain length (D.P.) for total over-all effects. It is concluded that the length of the cellulose molecule (D.P.) is an important factor in the physical properties of cotton fibers. All multiple correlations, including the fiber properties used in the simple correlations, were highly significant for varieties within locations and for over-all effects. Spiral structure and chain length (D.P.) when correlated with Pressley strength gave the highest coefficient of correlation.

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.

Further Counts of Bacteria on U.S. Commercial Raw Cotton Fiber

As a result of a continuing interest in bacteria as a possible cause of byssinosis, previously reported counts of bacteria on U.S. cotton have now been extended. Counts have been made on 144 classers samples from the 1981 crop by methods used previously with samples from the 1980 crop. The 1981 crop again exhibited great sample-to-sample variation in total bacteria and gram negatives within the same grade and growth area. Gram-negative bacteria were found at a million or more per gram of fiber in some classers samples from the Southeast, Midsouth, and Texas-Oklahoma. Cottons from Californias San Joaquin Valley, however, consistently showed bacterial counts much lower than the national average, continuing a trend shown in the 1980 crop. No constant or even near-constant proportionality occurred between numbers . for total bacteria and for gram negatives. In an additional series of 80 samples from Cone Mills Corporation, California cottons again showed exceptionally low bacterial counts. Bacterial numbers did not vary in any constant relation to the fibers micronaire value.

Microscopic Observations on Fungi Associated with Cotton Boll-Rot Fibers

Cotton boll-rot fibers were examined microscopically to determine the manner in which fungi grow on them. Cellulose decomposing boll-rot fungi wound around the fibers, paralleling closely the helical structure of the secondary wall; non-cellulose decomposers did not wind. Cellulose decomposers penetrated through the secondary walls and grew in the lumens; non-cellulose decomposers did not. Some fungi formed spores in the lumens. Mounting fibers in NaOH solutions made fungi easier to see, as did differential staining with Niagara Sky Blue 6B or mounting in cuprien. The cuprien caused swelling of the cellulose or its complete solution without visibly attacking the fungus.

A Review on the Kinds of Potentially-Byssinogenic Gram-Negative Bacteria that Occur on Raw Cotton Fiber

Byssinosis is a pulmonary problem experienced by some workers in areas of textile mills where cotton, flax, or other fibers are being mechanically processed prior to spinning. It has long been associated with dust in the air of the mill. As it occurs in U.S. cotton mills, byssinosis has been attributed at least in part to a gram-negative endotoxin-bearing bacterial component of the dust dispersed from fiber into air (Jacobs and Wakelyn, 1988). Bacteria, including gram-negatives, have been shown to grow on the fiber in open bolls before harvest; such growth occurs especially during rainy weather (Simpson and Marsh, 1986; Simpson et al., 1987b). Bacterial growth on fiber is minimal in the San Joaquin Valley of California, where the weather is exceptionally dry in the period between boll opening and harvest (Simpson and Marsh, 1985). Until recently, the gram-negative bacteria on commercial cotton fiber have been only incompletely identified. We briefly review here the identification of such bacteria and discuss practical implications of these findings in relation to the byssinosis problem.

Bacterial Counts on Commercial U.S. Cotton Fiber and their Possible Relation to Byssinosis in Cotton Mills

Byssinosis is a pulmonary problem among workers in cotton and flax spinning mills. It has been associated for many years with exposure to dust in millair but the active causative factor (s) in the dust have been unknown. Recently, however, evidence from several sources has led to the belief that bacteria are probably the incitant of the acute phase of the disease in cotton spinning mills. The bacteria are fiber - borne and are dispersed into air during processing. They are thought to trigger the bronchial constriction which is the basic cause of the breathing difficulty characteristic of acute byssinosis.