Development of an ideal starch saccharification process using amylolytic enzymes from thermophiles

Abstract

The extensive efforts to screen thermophilic fungi and bacteria, isolated from various environmental samples, have resulted in the selection of Thermomucor indicae-seudaticae, Geobacillus thermoleovorans NP33 and G. thermoleovorans NP54 for the production of glucoamylase, amylopullulanase and alpha-amylase, respectively. Submerged and solid-state fermentation processes were optimized for maximizing the secretion of glucoamylase by T. indicae-seudaticae. The production of amylopullulanase and alpha-amylase by NP33 and NP54 in submerged fermentation was also optimized. Glucoamylase was optimally active at pH 7.0 and 60 degrees C and was shown to saccharify soluble as well as raw starches. Amylopullulanase and alpha-amylase exhibited optima at pH 7.0 and 100 degrees C and saccharified starch efficiently. Differential inhibition and action on mixed substrates clearly suggested that there are two separate active sites for alpha-amylase and pullulanase activities of amylopullulanase. Both alpha-amylase and amylopullulanase are high maltose-forming and Ca(2+)-independent. These amylolytic enzymes have been shown to be useful in starch saccharification alone and in combination.

Production of thermostable and neutral glucoamylase using immobilized Thermomucor indicae-seudaticae

“…Thermomucor indicae-seudaticae has recently been shown to produce a thermostable and neutral glucoamylase, which finds potential application in the saccharification of raw and soluble starches (Satyanarayana et al 2004). The enzyme is optimally active at 60°C and pH 7.0 (Kumar and Satyanarayana 2003), a rare feature (optimal activity at neutral pH) of fungal glucoamylases that holds tremendous potential in simplifying the process of starch saccharification.…”

Screening for and Identification of Starch-, Amylopectin-, and Pullulan-Degrading Activities in Bifidobacterial Strains

“…It is composed exclusively of ␣-glucopyranose units that are linked to each other by ␣-1,4-or ␣-1,6-glucosidic bonds. The two high-molecular-weight components of starch are ␣-amylose (representing a 15 to 25% weight fraction of starch), which is a linear polymer composed exclusively of ␣-1,4-linked glucopyranose residues, and amylopectin (representing a 75 to 85% weight fraction of starch), which is also an ␣-1,4-linked glucopyranose polymer but in addition contains ␣-1,6-glycosidic linkages representing branch points occurring at every 17 to 26 residues (45). ␣-Amylose chains, which are not soluble in water but form hydrated micelles, are polydisperse, and their molecular masses vary from hundreds to thousands of kilodaltons.…”

The Role of Extremophilic Microorganisms and their Bioproducts in Food Processing and Production

“…The commercially available preparations are generally produced by Klebsiella and Bacillus spp., as well as the fungus Trichoderma (Doman-Pytka and Bardowski, 2004). However, some thermophiles also produce pullulanases: Thermoanaerobacterium thermosaccharoliticum and the thermoalkaliphile Anaerobranca gottschalkii, which produces a heat and alkali-stable type I pullulanase (Bertoldo et al, 2004), Rhodothermus marinus (Gomes et al, 2003), and Geobacillus thermoleovorans NP33 (Satyanarayana et al, 2004).…”

“…(Gill and Kaur, 2004), Clostridium sp. 0005 (Ohnishi et al, 1992), Thermomucor indicae-sendaticae (Satyanarayana et al, 2004), Thermoanaerobacter tengcongensis (Zheng et al, 2010) and the archaeal species Sulfolobus solfataricus (Kim et al, 2004), Thermoplasma acidophilum (Dock et al, 2008), Picrophilus torridus, and Picrophilus oshimae. The latter three archaeal species produce glucoamylases that are optimally active at pH 2 and 90 • C, with catalytic activity remaining at pH values as low as 0.5 and at 100 • C (Egorova and Antranikian, 2005).…”