Purification, biochemical characterization, and biotechnological applications of a multifunctional enzyme from the Thermoascus aurantiacus PI3S3 strain

The filamentous Thermoascus aurantiacus fungus characterized by its thermophilic nature, is recognized as an exceptional producer of various enzymes with biotechnological applications. This study aimed to explore biotechnological applications using polygalacturonase (PG) derived from the Thermoascus aurantiacus PI3S3 strain. PG production was achieved through submerged fermentation and subsequent purification via ion-exchange chromatography and gel filtration methods. The crude extract exhibited a diverse spectrum of enzymatic activities including amylase, cellulase, invertase, pectinase, and xylanase. Notably, it demonstrated the ability to hydrolyze sugarcane bagasse biomass, corn residue, and animal feed. The purified PG had a molecular mass of 36 kDa, with optimal activity observed at pH 4.5 and 70 °C. The activation energy (Ea) was calculated as 0.513 kJ mol-1, highlighting activation in the presence of Ca2+. Additionally, it displayed apparent Km, Vmax, and Kcat values of at 0.19 mg mL-1, 273.10 U mL-1, and 168.52 s-1, respectively, for hydrolyzing polygalacturonic acid. This multifunctional PG exhibited activities such as denim biopolishing, apple juice clarification, and demonstrated both endo- and exo-polygalacturonase activities. Furthermore, it displayed versatility by hydrolyzing polygalacturonic acid, carboxymethylcellulose, and xylan. The T. aurantiacus PI3S3 multifunctional polygalacturonase showed heightened activity under acidic pH, elevated temperatures, and in the presence of calcium. Its multifunctional nature distinguished it from other PGs, significantly expanding its potential for diverse biotechnological applications.

Biopolishing of denim by the recombinant xylanase II of Caulobacter crescentus

Denim, also known as jeans, is a fabric made up of braided cotton threads dyed indigo blue, whose fibers contain approximately 10% of non-cellulosic impurities that reduce its commercial value. Microbial enzymes can act in the cleaning and desizing processes of jeans, improving their color, softness, and covering capacity. The recombinant Xylanase II (XynA2) from the aquatic bacterial Caulobacter crescentus (C. crescentus), previously characterized in terms of its biochemical features, was applied to the biotreatment of jeans to clean and degum it. The biotreatment performance was evaluated in terms of tissue weight loss, amount of reducing sugars released and analysis of the images obtained by scanning electron microscopy (SEM). Biotreated tissues, at 12 and 24 h, showed a dry weight loss of 4.9 and 6.6%, respectively. The reducing sugars amount released after XynA2 action over the jean's fibers showed statistically significant values when compared with each other and with their respective controls. SEM images clearly shown that the fabric treated for 12 h presented a smooth and polished surface, while the fabric treated for 24 h showed the cotton fibers broken, displaying severe damage to the textile. The best treatment for the jeans was in the presence of 1 U mg-1 XynA2 at pH 8 and 60 °C during 12 h. In conclusion, XynA2 of C. crescentus was satisfactorily applied for the biopolishing of denim jeans being a more sustainable alternative to the use of chemical and abrasive processes to obtain the same effects.

Evaluation of microfiber release from jeans: the impact of different washing conditions

Microplastic particles are a burgeoning population crisis in the marine environment. This research examines the emission of microfibers from three different jeans (garments) during domestic washing. The jeans types, washing temperature, washing duration, spin speed, detergent types, and addition of conditioner are the main factors for this research work. The average length and diameter of the microfibers for the 100% PET jeans (jeans-P) has 7800 ± 4000 μm and 11.9±3.2 μm and for polyester/cotton jeans (jeans-PB) has 4900 ± 2200 μm 17.4±4.8 μm, respectively. The maximum microfiber released was observed in the rigorous washing treatment (90 min, 60°C, 1400 rpm, powder detergent with the presence of conditioner). The surmised number of microfibers discharged from the 1 kg wash load of jeans-P was calculated within the extent of 2300000-4900000 microfibers, and it is varied by the washing treatments.

Risk assessment due to dermal exposure of trace elements and indigo dye in jeans: Migration to artificial sweat

The concentration of a number of trace elements (Ag, Al, As, B, Ba, Be, Bi, Cd, Cr, Co, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Sc, Se, Sm, Sr, Sn, Tl, Ti, V and Zn) were determined in 42 commercialized denim garments (jeans and shirts), being dermal exposure subsequently assessed. Migration experiments with artificial acid and basic sweat were also conducted to determine the release of these elements, as well as indigo dye. In a similar way than for the total content, Mg (124 and 99.4 µg/g) and Mn (27.1 and 7.20 µg/g) showed the highest concentrations in both artificial sweat, acid and basic, respectively. Indigo dye migrated at levels ranged from 3.22 to 7.76 mg/g, being higher in dark than in light blue fabrics. The levels of trace elements and indigo were analysed according to materials of fabric, colour, brand, and eco-labelling. Using total content and migrations rates, dermal exposure to trace elements for adult men, women and teenagers were calculated under the two sweat extractions. Non-carcinogenic and carcinogenic risks due to dermal exposure to the elements here analysed in cloths were assessed. Both risks were in the limits of safe to according to international regulations. However, the maximum exposure to Sb reached a hazard quotient (HQ) of 0.3 in clothes partially made of polyester. Despite some authors have established that indigo is an agonist of the aril receptor, health risks due to exposure to indigo dye were not calculated due the lack of toxicological data.