This study was conducted to establish optimal temperature, pH and incubation time for bacteria from gin trash, for enhancing wax removal during cotton bioscouring. Universal Rotatable Experimental Design was used for the process of optimisation and efficiency assessed by the percentage weight loss after solvent extraction of the treated fibres. Optimum wax of 0.765% out of 1.2% present in the fibres was removed at 45°C, pH 8 within 1 h. Minitab 15 and Monte Carlos were used for the parameter modelling and sensitivity analysis. A second-order polynomial regression model was fitted and found adequate with a determination coefficient, R 2 , of 0.94032 (p < 0.005). At 45°C, pH 8, maximum 0.747% wax was removed by the bacteria in pectinase treatment within 1 h. 0.752% wax was removed from bulkier treated fibres, without significant change in fibre strength. Temperature was found to be the most significant variable in the bacterial cotton wax removal.

Purpose Bacterial exopolysaccharides (eps) have fascinating chemical compositions, properties and structures which could be used in the modification of natural fibres. Bacterial eps have therefore been used to modify plant cellulose fibre surface and impart desired properties. The purpose of this paper is therefore to investigate the influence of gin trash cultured bacteria eps on the physical and structural properties of cotton fibres. Design/methodology/approach Gin trash soil sample was collected from a ginnery in Kenya, and physiochemical and microbial characterization was done. The soil sample was then fermented for 24 h before being used to treat raw cotton fibres at varied conditions of temperature, pH and treatment time periods. Physical and structural properties of the treated fibres were then determined using USTER HVI-1000 M700, Fourier transform infrared, scanning electron microscope (SEM) and X-ray diffraction (XRD) and compared with those of the raw fibres. Findings The bacteria broth treated fibres were found to have increased in strength, spinning consistency index, elongation and fineness by 25.44, 24.30, 11.70 and 3.60%, respectively. The variations were attributed to interactions of bacterial eps with cotton cellulose through hydrogen bonding. SEM and XRD analysis revealed an increase in fibre surface roughness and crystallinity, respectively. Originality/value Bacterial eps have been used to modify plant cellulose fibre surface and impart desired properties. Eps producing bacteria have been isolated from different habitats such as saline water, soil samples, food wastes and petroleum-contaminated soil. To the best of the authors’ knowledge, bacterial eps cultured from gin trash soil sample for modification of cotton fibres have however not been previously done, hence the originality of the current study.