Production of raw starch degrading enzyme by the thermophilic filamentous bacterium Laceyella sacchari LP175 and its application for ethanol production from dried cassava chips

Abstract

Physical factors that enhanced the production of raw starch degrading enzyme by a thermophilic filamentous bacterium, Laceyella sacchari LP175 in a 3 L airlift fermenter, were optimized at a pH of 6.5, a temperature of 45°C, and an aeration rate of 0.5 vvm using a central composite design. This yielded 278 U/mL, at 36 h cultivation, an increase in enzyme production and productivity of 1.53‐ and 2.04‐fold, respectively, as compared with a shaking flask cultivation. Raw starch degrading enzyme produced by L. sacchari LP175 with commercial glucoamylase synergistically enhanced the hydrolysis of 300 g/L dried cassava chips (71% starch content) to 157 g/L reducing sugars, equivalent to 66.3% hydrolysis at pH 6.5 and 50°C for 12 h. The comparative study on bioethanol production in a non‐sterile system from dried cassava chip by three different processes; the maximum production, 90.9 g/L (88% theoretical yield), was obtained by modified simultaneous saccharification and fermentation at 50°C for 6 h and subsequent fermentation by the thermotolerant Kluyveromyces marxianus DMKU‐KS07 at 42°C within 18 h with the highest productivity of 3.79 g/L/h. The other processes tested – separate hydrolysis and fermentation and simultaneous saccharification and fermentation – yielded 83 and 51.6 g/L of ethanol, respectively.

Production of first- and second-generation ethanol for use in alcohol-based hand sanitizers and disinfectants in India

“…The annual production of cassava is approximately 250 million tons with the largest production in the African region providing 50% of the world's production, and Nigeria is the leading producer country with the annual production of more than 50 million tons [69]. Apart from its use in food and feed industry, cassava is widely used for ethanol production in countries like China, Thailand, and Vietnam in the form of dried chips, which are stored for longer use in the plant [70]. In a study, hydrolysis of cassava starch with enzyme derived from bacteria Laceyell asacchari LP175 supplemented with commercial glucoamylase was investigated at 50°C for 12 h resulting into sugar concentration of 157 g/l with 66% hydrolysis rate, and subsequent fermentation of obtained sugars using S. cerevisiae M30 at 50°C for 6 h followed by fermentation with K. marxianus DMKU-KS07 at 42°C for 18 h resulting into 90.9 g/l ethanol concentration, which corresponds to 88% of theoretical yield and ethanol productivity of 3.79 g/l/h [71].…”

Gene sequence, modeling, and enzymatic characterization of α-amylase AmyLa from the thermophileLaceyellasp. DS3

“…This indicates an intermediate temperature stable a-amylase that is useful for the baking industry [46]. In comparing to other Thermoactinomyces amylases, optimum pH, and temperature of AmyLa (pH 7, 50°C) are distinct from AmyTV1 (pH 4.8-6, 62.5°C) [27], TVA I (pH 5, 70°C) [28], and those from Laceyella sacchari (pH 6.5, 45°C) [22]. The activation energy of AmyLa a-amylase was found to be 196.1 kJ.…”

“…Therefore, given the size of the market interest in improving enzyme production and activity is intense. Research has focused on α‐amylase production from thermophiles such as Thermoactinomycetes. Based on molecular phylogenetics, Thermoactinomycetaceae has been reclassified into Bacillales (phylum Firmicutes) although it has long been classified in actinomycetales .…”

“…The genus Thermoactinomyces has been extended into new genera based on phylogenetic analyses . Based on the new taxonomy, α‐amylase can be produced by Laceyella species as reported by Lomthong et al .…”

Potential of Recombinant Raw Starch‐Degrading Enzyme from Escherichia coli for Sugar Syrup and Bioethanol Productions Using Broken Rice Powder as Substrate

“…[3] RSDEs have been reported for application in various fields such as ethanol, baking, paper, and sugar syrups. [4][5][6][7] Currently, the RSDE gene (lsa175) from Laceyella sacchari LP175 was sequenced, characterized, and expressed in Escherichia coli BL21 against raw cassava starch at pH 6.5 and a temperature of 50 °C. [3] The recombinant LsA175 showed higher production of sugar syrups than the conventional 𝛼-amylase at 50 °C and offers a choice for enzyme production in terms of energy consumption savings in various starch conversion processes.…”