Produção de pectinases fúngicas a partir do extrato aquoso da algaroba (Prosopis juliflora (SW) DC)

Abstract

The use of the aqueous extract of mesquite (Prosopis juliflora (Sw.) DC) as a substrate for biotechnological processes becomes an interesting strategy, as it has a composition rich in carbohydrates and proteins. Pectinolytic enzymes are examples of enzymes that can be synthesized by filamentous fungi and have several industrial applications. Thus, the present study aimed to evaluate the potential for using mesquite aqueous extract as a substrate for the production of pectinolytic enzymes from filamentous fungi. For enzyme production, the fungal isolates Paecilomyces sp. TP08. Aspergillus sp NA01, and Penicillium sp, cultivated in 1% (v/v) mesquite aqueous extract with pH adjusted to 5.8. For cultures, an aliquot of 10% (v/v) of a conidial suspension at 1x107 conidia/mL was added to each of the culture flasks to a final medium volume of 100 mL. Samples were taken every 24 h to check enzymatic activity with the fungal isolates. The cultivation was monitored by the determination of microbial growth, dry biomass method, by the determination of substrate consumption, DNS method and by enzymatic activity using 0.5% (w/v) citrus pectin in acetate buffer as a specific substrate (pH 5.5). The aqueous extract of mesquite (lot 2018) presented an amount of TSS equal to 28 ºBrix, which means that the solution has enough fermentable carbohydrates to be used as a substrate in transformation processes through microbial action. The determination of the ART of 210 g/L of complex sugars proves the amount of sugars present in the sample in terms of glucose. In the same sense, the TSS and ART content in the aqueous extract (lot 2023) was determined, 19 ºBrix and 180 g/L, respectively, considered a significant source of sugars for the development of microorganisms in biotechnological processes. The amount of pectin in the form of calcium pectate found in this work was 0.262 and 0.784, for mesquite extracts at 10% and 1%, respectively. Apple juice had an SST of 16.1 ºBrix and cashew juice 6.0 ºBrix. Regarding the production of pectinases, the results indicate that Aspergillus sp. NA01, on the fourth day, presented a production of 2,460 U/mL. As well as the rapid consumption of sugars, showing better results in relation to the production of pectinases, followed by Penicillium sp. and Paecilomyces sp. TP08, respectively. There was a reduction in absorbance values at 440 nm and 520 nm for the treated juices in relation to the control. This clarification was calculated at 0.26% and 0.21% for apple and cashew juices, respectively. Therefore, the results obtained were compared between fungal species, highlighting the fungal species Aspergillus NA01 sp. demonstrating that the production of pectinolytic enzymes from mesquite aqueous extract represents a promising approach in the biotechnology industry. The results show that the enzyme complex produced by the isolate Aspergillus sp NA01, in aqueous mesquite extract, can act as a clarifying agent in fruit juices, such as cashew and apple.