Invertase or β-D-fructofuranoside fructohydrolase (EC 3.2.1.26) was one of the foremost enzyme biocatalysts and established the primary concepts of most enzyme-kinetic principles. Invertases are glycoside hydrolases and occur mostly in microorganisms. Among microbial strains, for many decades yeast species have been extensively researched for invertase production, characterization, and applications in industries. Besides, limited literature is available on invertases from bacterial strains. The enzymic and molecular biological reports from bacterial invertases are scarce. In this minireview, occurrence, production, biochemical properties, and significance of transfructosylation of bacterial invertases are reported.

This study focused on the purification and characterization of an extracellular β-d-fructofuranosidase or invertase from JU12. The protein was purified by size exclusion chromatography with 5.41 fold and 10.87% recovery. The apparent molecular mass of the enzyme was estimated to be ~ 35 kDa using SDS-PAGE and confirmed by deconvoluted mass spectrometry. The fungal β-d-fructofuranosidase was suggested to be a monomer by native PAGE and zymography, and was found to be a glycoprotein possessing 68.92% carbohydrate content. The products of enzyme hydrolysis were detected by thin layer chromatography and revealed the monosaccharide units, d-glucose and d-fructose. β-d-fructofuranosidase showed enhanced activity at broad pH 4.0-9.0 and activity at a temperature range from 30 to 70 °C, while the enzyme was stable at pH 8.0 and 40 °C, respectively. The β-d-fructofuranosidase activity was lowered by metal ion inhibitors Ag and Hg whereas elevated by SDS and β-ME. The fungal β-d-fructofuranosidase was capable of hydrolyzing d-sucrose and the kinetics were determined by Lineweaver-Burk plot with of 10.17 mM and of 0.7801 µmol min. Additionally, the extracellular β-d-fructofuranosidase demonstrated tolerance to high ethanol concentrations indicating its applicability in the production of alcoholic fermentation processes.

The purification and biochemical characterization of extracellular β‐d‐fructofuranosidase from Bacillus subtilis LYN12 was carried out. The enzyme was purified 6.94 folds over the crude extract by gel filtration chromatography with recovery of 15.58%. The molecular mass of ∼66 kDa estimated by SDS‐PAGE was confirmed by LC‐MS as 64512.31 Da. Bacterial β‐d‐fructofuranosidase was found to be a glycoprotein with 62.64% carbohydrate content, and exhibited enhanced activities at broad pH, temperature and stable at pH 7.0, 40°C, respectively. The enzyme showed high affinity for d‐sucrose. Kinetic parameters Km and Vmax were 41.98 mM and 1.184 µmol/min, respectively. β‐d‐fructofuranosidase activity was inhibited by the divalent metal ions Cu2+ and Hg2+, whereas improved by Mg2+, Fe2+ and few sulphydryl group reagents. β‐d‐fructofuranosidase demonstrated ethanol tolerance up to 15% with 76.4% of activity. B. subtilis LYN12 invertase is suggested as a potential enzyme with suitable characteristics for numerous industrial applications. Practical applications β‐d‐fructofuranosidases are one of the industrially important carbohydrases utilized in many applications such as beverages, baking, confectionaries, nutraceuticals and also medicinal formulations. The production of β‐d‐fructofuranosidase from Bacillus subtilis LYN12 by solid‐state fermentation demonstrates the utilization of agro‐industrial wastes, such as wheat bran and molasses. The bacterial β‐d‐fructofuranosidase was produced extracellularly which aids in down‐streaming processes. Most of the industrial alcohol fermentations generally operate at 10%–14% (v/v) of ethanol at the end of fermentation. Interestingly, β‐d‐fructofuranosidase exhibited a significant tolerance towards ethanol, the tolerance level of the bacterial invertase indicates its potentiality in the alcoholic fermentation processes. On the other hand, B. subtilis LYN12 β‐d‐fructofuranosidase was found to be active at a broad pH and temperature range possessing high affinity for d‐sucrose. The biochemical characterization of the bacterial β‐d‐fructofuranosidase is crucial to understand the enzymic nature and properties.

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Bacillus subtilis LYN12 invertase possesses excellent fermenting capability to utilize agro-industrial residues under submerged and solid-state conditions. This could be a beneficial candidate in food and beverage processing industries.