Characterization of a thermophilic l-arabinose isomerase from Thermoanaerobacterium saccharolyticum NTOU1

Engineering the l-Arabinose Isomerase from Enterococcus Faecium for d-Tagatose Synthesis

“…The maximum concentrations of d -tagatose obtained from d -galactose using N -His- l -AI and C -His- l -AI were 105 and 46 mM, respectively, representing a 26% conversion yield in 24 h for N -His- l -AI and an 11% conversion yield in 48 h for C -His- l -AI ( Figure 5 ). The bioconversion yield of d -galactose into d -tagatose for other recombinant l -AIs ranges between 16% and 40% [ 12 , 22 , 27 ].…”

“…The samples were incubated at 50 °C and the amount of d -tagatose was determined by measuring the absorbance at 560 nm via the cysteine-carbazole sulfuric acid method [ 42 ]. One unit (U) of l -AI activity was defined as the amount of enzyme required for the production of one µmol of d -tagatose per minute under the reaction conditions [ 12 ]. The influence of pH on the activity of l -AI was determined employing 50 mM sodium acetate buffer (pH 5.6), 50 mM sodium phosphate buffer (pH 7.0), and 50 mM sodium bicarbonate buffer (pH 10).…”

“…l -Arabinose isomerase (EC 5.3.1.4) ( l -AI) encoded by araA -like genes has been the most studied enzyme for the conversion of d -galactose to d -tagatose due to the industrial viability of this process, since d -galactose can be obtained from the lactose contained in cheese whey as a cheap substrate [ 10 , 11 ]. For this reason, the production of d -tagatose from d -galactose using l -AI has been studied in recent years [ 6 , 11 , 12 , 13 ]. However, the enzymatic process still has a number of bottlenecks that need to be overcome, e.g., low protein concentration in the fermentation step using wild-type-producing strains [ 14 , 15 ], low productivity in the isomerization reaction, and reduced thermostability of the enzyme [ 16 , 17 ].…”

“…The production of l -AI has been reported by using wild type strains, e.g., Lactobacillus [ 18 , 19 ] or Enterococcus [ 11 ], as well as some recombinant microorganisms, e.g., Escherichia coli [ 10 , 20 ] Bacillus subtilis [ 21 ], or Lactobacillus plantarum [ 22 ]. In some cases, the recombinant l -AI has been fused to a His-tag to facilitate its purification (e.g., C-terminal His-tag fusion of l -AI from Thermotoga maritime [ 23 ] or Thermoanaerobacterium saccharolyticum NTOU1 [ 12 ] and N-terminal His-tag fusion of l -AI from Bacillus coagulans [ 24 ], Lactobacillus reuteri [ 22 ], or Thermus sp. [ 25 ]).…”

Advances in the enzymatic production of l-hexoses

“…The specific activities of the enzymes isolated from P. stutzeri, Caldicellulosiruptor saccharolyticus (Lin et al 2011), Thermotoga maritime (Park et al 2010), Thermoanaerobacterium saccharolyticum (Hung et al 2014), Bacillus pallidus (Poonperm et al 2007), M. loti (Takata et al 2011), and Bacillus subtilis (Park 2014) toward L-mannose were 81.6, 38, 15, 6, 4.52, 2.27, and 0.92 U mg −1 , respectively. In addition, L-fructose has also been produced from L-mannose with a conversion ratio of approximately 25 % by an enzyme reactor packed with cross-linked Streptomyces rubiginosus D-glucose isomerase crystals (Jokela et al 2002).…”