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<p>α-Amylases (EC 3.2.1.1) are endoenzymes that hydrolyze α-1,4-glycosidic bonds in starch to produce maltooligosaccharides with broad industrial applications (food, textile, fermentation, biofuels). Most α-amylases act only on gelatinized starch, but <i>Bacillus siamensis</i> JJC33M secretes a native enzyme (AmyJ33-ABC) active on both gelatinized and raw starch. The growth of <i>B. siamensis</i> JJC33M was evaluated, showing µ = 0.55&#xa0;h⁻<sup>1</sup>, Y<sub>p/s</sub> = 0.13&#xa0;g/g, Y<sub>x/s</sub> = 0.24&#xa0;g/g, Y<sub>p/x</sub> = 0.55&#xa0;g/g, and Q<sub>p</sub> = 0.063&#xa0;g/Lh, values comparable with other native production systems. AmyJ33-ABC was partially purified and characterized. The enzyme displayed optimal activity at pH 5.0 and 80&#xa0;°C, with <i>K</i><sub><i>m</i></sub> = 1.47&#xa0;mg/mL, <i>V</i><sub><i>max</i></sub> = 39.37 U/mg, and catalytic efficiency <i>K</i><sub><i>cat</i></sub><i>/K</i><sub><i>m</i></sub> = 22.31&#xa0;s⁻<sup>1</sup>&#xa0;mg⁻<sup>1</sup>&#xa0;mL, comparable with another native systems. At optimal conditions, it hydrolyzed 57.5% of gelatinized potato starch, generating glucose, maltose, maltotriose, maltotetraose, and minor maltooligosaccharides up to DP7. Structural modeling confirmed the canonical GH13 fold (A/B and C domains) and revealed three aromatic-rich surface-binding sites (SBS) located near the catalytic triad. These SBS may explain the enzyme activity on raw starch despite lacking a carbohydrate-binding module (CBM). AmyJ33-ABC combines dual activity on gelatinized and raw starch, acidic pH preference, and high-temperature optimum. These distinctive features highlight its potential for starch bioconversion in bakery, syrup, and related industries.</p>

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Production and application of α-amylase, native AmyJ33-ABC, from Bacillus siamensis JJC33M in gelatinized potato starch and its industrial potential

  • 期刊论文

  • 发表日期：

    2025年10月11日

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  • Sarahi Hernández-Heredia,
  • María Guadalupe Aguilar-Uscanga,
  • Cirilo Nolasco-Hipólito,
  • Sandra del Moral

摘要

α-Amylases (EC 3.2.1.1) are endoenzymes that hydrolyze α-1,4-glycosidic bonds in starch to produce maltooligosaccharides with broad industrial applications (food, textile, fermentation, biofuels). Most α-amylases act only on gelatinized starch, but Bacillus siamensis JJC33M secretes a native enzyme (AmyJ33-ABC) active on both gelatinized and raw starch. The growth of B. siamensis JJC33M was evaluated, showing µ = 0.55 h⁻1, Yp/s = 0.13 g/g, Yx/s = 0.24 g/g, Yp/x = 0.55 g/g, and Qp = 0.063 g/Lh, values comparable with other native production systems. AmyJ33-ABC was partially purified and characterized. The enzyme displayed optimal activity at pH 5.0 and 80 °C, with Km = 1.47 mg/mL, Vmax = 39.37 U/mg, and catalytic efficiency Kcat/Km = 22.31 s⁻1 mg⁻1 mL, comparable with another native systems. At optimal conditions, it hydrolyzed 57.5% of gelatinized potato starch, generating glucose, maltose, maltotriose, maltotetraose, and minor maltooligosaccharides up to DP7. Structural modeling confirmed the canonical GH13 fold (A/B and C domains) and revealed three aromatic-rich surface-binding sites (SBS) located near the catalytic triad. These SBS may explain the enzyme activity on raw starch despite lacking a carbohydrate-binding module (CBM). AmyJ33-ABC combines dual activity on gelatinized and raw starch, acidic pH preference, and high-temperature optimum. These distinctive features highlight its potential for starch bioconversion in bakery, syrup, and related industries.