Analysis of the products from enzymatic scouring of cotton

Eco-friendly scouring of cotton knit fabrics with enzyme and soapnut: An alternative to conventional NaOH and synthetic surfactant based scouring

Eye-catching, aesthetic fashions often suppress its untold dark story of unsustainable processing including hazardous wet treatment. Considering the risks imposed by conventional cotton scouring and following the trend of scouring with enzymes, this study was undertaken to evaluate the bioscouring of cotton knit fabric involving saponin-enriched soapnut as a natural surfactant, applied from a bath requiring a few chemicals and gentle processing conditions, contributing to the eco-friendliness. The proposed application was compared to synthetic detergent engaged enzymatic scouring as well as the classic scouring with Sodium hydroxide. A cellulolytic pectate lyase enzyme (0.5%-0.8% o.w.f) was applied at 55 °C for 60 min at pH 5-5.5 with varying surfactant concentrations. A low concentration of soapnut extract (1 g/L to 2 g/L) was found sufficient to assist in the removal of non-cellulosic impurities from the cotton fabric after bioscouring with 0.5% o.w.f. enzyme, leading to good hydrophilicity indicated by an average wetting time of 4.86 s at the expense of 3.1%-3.8% weight loss. The scoured fabrics were further dyed with 1% o.w.f. reactive dye to observe the dyeing performance. The treated samples were characterized in terms of weight loss, wettability, bursting strength, whiteness index, and color value. The proposed application confronted level dyeing and the ratings for color fastness to washing and rubbing were 4-5 for all of the samples scoured enzymatically with soapnut. The study was also statistically analyzed and concluded.

Functional analysis of the degradation of cellulosic substrates by a Chaetomium globosum endophytic isolate

Most photosynthetically fixed carbon is contained in cell wall polymers present in plant biomasses, the largest organic carbon source in the biosphere. The degradation of these polymers for biotechnological purposes requires the combined action of several enzymes. To identify new activities, we examined which enzymes are activated by an endophytic strain of Chaetomium globosum to degrade cellulose-containing substrates. After biochemical analyses of the secretome of the fungus grown on cellulose or woody substrates, we took advantage of the available genomic data to identify potentially involved genes. After in silico identification of putative genes encoding either proteins able to bind to cellulose or glycohydrolases (GHs) of family 7, we investigated their transcript levels by reverse transcription-quantitative PCR (RT-qPCR). Our data suggest that eight genes compose the core of the cellulose-degrading system of C. globosum. Notably, the related enzymes belong structurally to the well-described GH families 5, 6, 7, 16, and 45, which are known to be the core of the cellulose degradation systems of several ascomycetes. The high expression levels of cellobiose dehydrogenase and two GH 61 enzymes suggest the involvement of this oxidoreductive synergic system in C. globosum. Transcript analysis along with relevant coding sequence (CDS) isolation and expression of recombinant proteins proved to be a key strategy for the determination of the features of two endoglucanases used by C. globosum for the first attack of crystalline cellulose. Finally, the possible involvement of transcriptional regulators described for other ascomycetes is discussed.

Characterization of Thermobifida fusca cutinase-carbohydrate-binding module fusion proteins and their potential application in bioscouring

Cutinase from Thermobifida fusca is thermally stable and has potential application in the bioscouring of cotton in the textile industry. In the present study, the carbohydrate-binding modules (CBMs) from T. fusca cellulase Cel6A (CBM(Cel6A)) and Cellulomonas fimi cellulase CenA (CBM(CenA)) were fused, separately, to the carboxyl terminus of T. fusca cutinase. Both fusion enzymes, cutinase-CBM(Cel6A) and cutinase-CBM(CenA), were expressed in Escherichia coli and purified to homogeneity. Enzyme characterization showed that both displayed similar catalytic properties and pH stabilities in response to T. fusca cutinase. In addition, both fusion proteins displayed an activity half-life of 53 h at their optimal temperature of 50°C. Compared to T. fusca cutinase, in the absence of pectinase, the binding activity on cotton fiber was enhanced by 2% for cutinase-CBM(Cel6A) and by 28% for cutinase-CBM(CenA), whereas in the presence of pectinase, the binding activity was enhanced by 40% for the former and 45% for the latter. Notably, a dramatic increase of up to 3-fold was observed in the amount of released fatty acids from cotton fiber by both cutinase-CBM fusion proteins when acting in concert with pectinase. This is the first report of improving the scouring efficiency of cutinase by fusing it with CBM. The improvement in activity and the strong synergistic effect between the fusion proteins and pectinase suggest that they may have better applications in textile bioscouring than the native cutinase.