Production and Catalytic Properties of Amylases fromLichtheimia ramosaandThermoascus aurantiacusby Solid-State Fermentation

Abstract

The present study compared the production and the catalytic properties of amylolytic enzymes obtained from the fungi Lichtheimia ramosa (mesophilic) and Thermoascus aurantiacus (thermophilic). The highest amylase production in both fungi was observed in wheat bran supplemented with nutrient solution (pH 4.0) after 96 hours of cultivation, reaching 417.2 U/g of dry substrate (or 41.72 U/mL) and 144.5 U/g of dry substrate (or 14.45 U/mL) for L. ramosa and T. aurantiacus, respectively. The enzymes showed higher catalytic activity at pH 6.0 at 60°C. The amylases produced by L. ramosa and T. aurantiacus were stable between pH 3.5–10.5 and pH 4.5–9.5, respectively. The amylase of L. ramosa was stable at 55°C after 1 hour of incubation, whereas that of T. aurantiacus maintained 60% of its original activity under the same conditions. Both enzymes were active in the presence of ethanol. The enzymes hydrolyzed starch from different sources, with the best results obtained with corn starch. The enzymatic complex produced by L. ramosa showed dextrinizing and saccharifying potential. The enzymatic extract produced by the fungus T. aurantiacus presented only saccharifying potential, releasing glucose monomers as the main hydrolysis product.

Catalytic properties of cellulases and hemicellulases produced by Lichtheimia ramosa: Potential for sugarcane bagasse saccharification

“…As a substrate, wheat bran has good water-retaining capacity, and its physical structure favors the transfer of mass inside a solid matrix (Oliveira et al, 2016). In addition, its high protein (13-19%), cellulose, and hemicellulose (above 39%) content, combined with the low lignin content (3%-6%), are characteristics that favor microbial growth and, in turn, their production of enzymes (Falkoski et al, 2013;Kilikian et al, 2014).…”

“…Low moisture content in a solid substrate decreases the solubility and diffusion of nutrients, as well as the stability of extracellular enzymes, and hinders microbial growth (Delabona et al, 2013;Sadaf and Khare, 2014). On the other hand, high levels of moisture may lead to the aggregation of substrate particles, thus reducing the porosity of the solid matrix, which limits heat dissipation and gas exchange (Oliveira et al, 2016).…”

Biotransformation of fruit residues via solid state bioprocess using Lichtheimia ramosa

“…The substrate choice is a very important factor for an efficient bioprocess [4]. The use of agricultural residues as substrates provides an alternative for SSB because it adds value to these materials and assists in the mitigation of environmental problems [5]. Fruit wastes are rich in starch, cellulose, soluble sugars and organic compounds [6] and those of interest for SSB include apple, grape, kiwi, orange, pineapple, pequi, and guavira, among others [4,[7][8][9] The utilization of SSB to produce enzymes and protein enrichment has received great attention due to the low level of applied technology and efficiency in the conversion of substrates [4], with several applications widely reported in the literature, as amylase production to be used in the pharmaceutical and food industry, use of carboxymethylcellulase (CMCase), xylanase, and β-glucosidase have potential to hydrolyze plant cell wall e lipases are very important both from a physiological aspect, since they hydrolyze oils and fats into free fatty acids [9][10][11].…”

“…Lichtheimia ramosa has vigorous mycelial growth up to 30 days of cultivation on substrates with araticum, pequi and guavira fruit residues in SSB [1,4]. Furthermore, it was previously reported as a β-glucosidase, amylase, CMCase and xylanase enzyme producer [2,5,13,14] beyond enabling the bioconversion of residual fruit substrates [4]. It was reported elsewhere no deleterious effects from feeding a high moisture, ensiled, moldy shelled corn with L. ramosa and other fungi to lactating dairy cows [15].…”

Estudo da alteração do perfil de proteínas de fungos filamentosos em diferentes condições de cultivo utilizando ferramentas proteômicas e ensaios enzimáticos

“…No cultivo com farelo de trigo, as máximas produções de amilase pelos fungos Lichtheimia ramosa e Thermoascus aurantiacus foram de 417,2 U/g e 144,5 U/g, respectivamente (OLIVEIRA et al, 2016 A maior produção de lacase foi obtida com palha de arroz (0,3 U/g) no período inicial do cultivo, equivalente a cerca de 0,03 U/mL, em 24 h de bioprocesso.…”