Evidence of thermostable amylolytic activity from Rhizopus microsporus var. rhizopodiformis using wheat bran and corncob as alternative carbon source

Abstract

Rhizopus microsporus var. rhizopodiformis produced high levels of alpha-amylase and glucoamylase under solid state fermentation, with several agricultural residues, such as wheat bran, cassava flour, sugar cane bagasse, rice straw, corncob and crushed corncob as carbon sources. These materials were humidified with distilled water, tap water, or saline solutions--Segato Rizzatti (SR), Khanna or Vogel. The best substrate for amylase production was wheat bran with SR saline solution (1:2 v/v). Amylolytic activity was still improved (14.3%) with a mixture of wheat bran, corncob, starch and SR saline solution (1:1:0.3:4.6 w/w/w/v). The optimized culture conditions were initial pH 5, at 45 degrees C during 6 days and relative humidity around 76%. The crude extract exhibited temperature and pH optima around 65 degrees C and 4-5, respectively. Amylase activity was fully stable for 1 h at temperatures up to 75 degrees C, and at pH values between 2.5 and 7.5.

Production of fibrolytic enzymes by Aspergillus japonicus C03 using agro-industrial residues with potential application as additives in animal feed

“…The best result (32%) for xylanase production was obtained using Khanna solution, while for cellulase production, SR, and Khanna mineral solutions increased around 25% (Table 3). PeixotoNogueira et al [11] observed an increase of amylase production (23.8%) in Rhizopus microsporus var. rhizopodiformis culture supplemented with SR solution and using wheat bran as carbon source.…”

“…Effect of different agro-industrial residues and forages on enzyme production Agricultural countries produce large quantities of residual sub products which may be used as a carbon source to produce valuable biotechnological products by fermentation [11]. With this objective, low cost and abundant agricultural residues and forages were tested, in order to know if they could support A. japonicus C03 growth and enzyme production.…”

“…Maximum yield of xylanase was obtained from the mixture containing soy bran plus crushed corncob (1:3 w/w) humidified with Khanna saline solution at 30°C for 3 days. Independent researchers have recognized corncob as a useful and costeffective nutrient, because it is largely produced as a byproduct during the corn processing [11]. The maximum yield of cellulase was obtained in a medium containing wheat bran with sugarcane bagasse (3:1 w/w) humidified with SR saline solution at 30°C during 6 days of incubation.…”

“…The pH optima were determined by monitoring enzyme activities in the pH range 2.5-10. The buffers used were McIlvaine, containing 0.1 M citric acid and 0.2 M Na 2 HPO 4 (2.5-5.5); 50 mM sodium acetate (6.0); 50 mM Tris-HCl (7-9) and 50 mM glycine-NaOH (10)(11)(12). The optimum activity of both enzymes was found at pH 4.0 (Fig.…”

“…The SSF substrates were prepared by mixing 3 mL of sterilized distilled water, 1 mL of fungus suspension, and 2 g of one of the following residues: wheat bran, soy bran, sugarcane bagasse, crushed corncob, crushed corn, green grass (Tifton-85 and Brachiaria genera), hay ensilage, eucalyptus sawdust, orange peel, rice straw, or corn straw. Mixtures of some of these residues in three different proportions (1:3, 2:2 and 3:1 w/w) [11] were also carried out in some experiments. After 5 days of cultivation (or as indicated), all culture media were obtained by agitation for 30 min with 30 mL of distilled water at 4°C, followed by vacuum filtration using gaze and Whatman # 2 filter paper.…”