Gram-Negative Bacterial Content and Fiber Properties of Raw Cotton

Abstract

The content of gram-negative bacteria was determined for 109 samples of the 1978 crop of American upland raw cotton derived from seven grade divisions and five visual color groups. The populations of gram-negative bacteria entrained in these raw cottons varied from 1.5 X 1010 to 1.5 X 1014 for standard bale size (217.7 kg) lots. Raw cotton fiber parameters, including upper-half-mean length, length uniformity, strength, micronaire, maturity, and fineness, were all significantly and inversely correlated with the content of entrained gram-negative bacteria. The yellowness of raw cottons as measured by the cotton colorimeter was significantly and positively correlated with bacterial content. About half of the variability of gram-negative bacterial content in raw cotton samples of the 1978 American upland crop can be accounted for by variation in micronaire ( r2 = 0.504).

Endotoxin Content and Fiber Properties of Raw Cotton

“…As in past studies [2] the content of GNB varied enormously between samples, covering the range from 1.5 X 10'°t o 1.5 X 10&dquo; colony forming units per standard 217.7 kg (480 pound) bale [3]. The number of GNB was highest for cottons from the tinged and yellow-stained color groups, generally exceeding 8 X 10'2 colony forming units per bale [3].…”

“…When these cottons were analyzed separately, we found that fiber maturity, but not fiber fineness, was significantly and inversely correlated with endotoxin level (Table II). For these cottons the maturity component of micronaire [2] and not fiber perimeter is related to endotoxin content. Accordingly fibers with very thin secondary walls or an absence of secondary wall development are those with the highest level of this microbial material.…”

“…In a previous study we reported that the content of gram negative bacteria (GNB) present in bales (217.7 kg) of raw cotton from the 1978 American upland crop varied from 1.5 X 10'° to 1.5 X 1014 colony forming units [2]. Raw cotton fiber parameters such as upper half mean (UHM) length, length uniformity, strength, micronaire, maturity, and fineness were all significantly and inversely correlated with the content of entrained GNB.…”

“…Raw cottons were also analyzed for maturity (maturity ratio, proportion of mature fibers, and causticaire maturity) and fineness (fineness in millitex and denier) characteristics using the IIC Shirley Fineness/ Maturity Tester. Descriptions of each of the aforementioned twelve fiber parameters are found in an earlier publication n [2].…”

“…Endotoxin and other microbiological determinations were carried out on replicate (3 to 6) 3 g samples of each raw cotton according to the Limulus amoebocyte lysate method used previously [2]. All microbiological determinations were made on raw cotton samples in April and May 1980.…”