β-Glucosidases are diverse group of enzymes with great functional importance to biological systems. These are grouped in multiple glycoside hydrolase families based on their catalytic and sequence characteristics. Most studies carried out on β-glucosidases are focused on their industrial applications rather than their endogenous function in the target organisms. β-Glucosidases performed many functions in bacteria as they are components of large complexes called cellulosomes and are responsible for the hydrolysis of short chain oligosaccharides and cellobiose. In plants, β-glucosidases are involved in processes like formation of required intermediates for cell wall lignification, degradation of endosperm’s cell wall during germination and in plant defense against biotic stresses. Mammalian β-glucosidases are thought to play roles in metabolism of glycolipids and dietary glucosides, and signaling functions. These enzymes have diverse biotechnological applications in food, surfactant, biofuel, and agricultural industries. The search for novel and improved β-glucosidase is still continued to fulfills demand of an industrially suitable enzyme. In this review, a comprehensive overview on detailed functional roles of β-glucosidases in different organisms, their industrial applications, and recent cloning and expression studies with biochemical characterization of such enzymes is presented for the better understanding and efficient use of diverse β-glucosidases.

Bacterial inoculants are known to possess plant growth promoting abilities and have potential as liquid biofertilizer application. Four phytase producing bacterial isolates (phytase activity in the range of 0.076–0.174 U/mL), identified as Advenella species (PB-05, PB-06, and PB-10) and Cellulosimicrobium sp. PB-09, were analyzed for their plant growth promoting activities like siderophore production, IAA production, HCN production, ammonia production, phosphate solubilization, and antifungal activity. All isolates were positive for the above characteristics except for HCN production. The solubilization index for phosphorus on Pikovskaya agar plates was in the range of 2–4. Significant amount of IAA (7.19 to 35.03 μg/mL) production and solubilized phosphate (189.53 to 746.84 μg/mL) was noticed by these isolates at different time intervals. Besides that, a greenhouse study was also conducted with Indian mustard to evaluate the potential of these isolates to promote plant growth. Effect of seed bacterization on various plant growth parameters and P uptake by plant were used as indicators. The plant growth promoting ability of bacterial isolates in pot experiments was correlated to IAA production, phosphate solubilization, and other in vitro tests. On the basis of present findings, isolate PB-06 was most promising in plant growth promotion with multiple growth promoting characteristics.

Heavy metals are the intrinsic component of the environment with both essential and nonessential types. Their excessive levels pose a threat to plant growth and yield. Also, some heavy metals are toxic to plants even at very low concentrations. The present investigation (a pot experiment) was conducted to determine the affects of varying chromium(VI) levels (0.0, 0.5, 1.0, 2.0, and 4.0 mg chromium(VI) kg−1 soil in the form of potassium dichromate) on the key enzymes of nitrogen metabolism in clusterbean. Chromium treatment adversely affect nitrogenase, nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate dehydrogenase in various plant organs at different growth stages as specific enzyme activity of these enzymes decreased with an increase in chromium(VI) levels from 0 to 2.0 mg chromium(VI) kg−1 soil and 4.0 mg chromium(VI) kg−1 soil was found to be lethal to clusterbean plants. In general, the enzyme activity increased with advancement of growth to reach maximum at flowering stage and thereafter decreased at grain filling stage.

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