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Abstract Background Actinidin is an anionic thiol-proteinase predominant and unique to Chinese gooseberry or kiwifruit, whose strong digestibility enables proteins or enzymes vulnerable to digestion. The arrangement of active cysteine–thiol residues (Cys22-Cys65, Cys56-Cys98, and Cys156-Cys206) stabilizes the catalytic unit, thus allowing an effective Inhibition of α-amylase protein on exposure to the highest concentrations of actinidin under optimum conditions. When starch-rich foods are consumed with kiwifruit, starch digestion may be slowed by the inactivation of α-amylase (digestive enzyme), specifically reducing the blood sugar levels by hindering starch digestion that is helpful in diabetes mellitus. Thus, the study aimed at actinidin purification, optimization for maximal activity, and its demonstration as a potential to degrade α-amylase. Results Protease showed a molecular mass of 27 kDa on SDS-PAGE analysis. One factor at a time method was applied for process optimization, increasing the actinidin yield up to 176.03 U/mg. The enzyme was stable at a wide pH range; however, it was most active and stable at pH 7.5. The enzyme possessed half‐life at 35 °C of 5.5 h, at 40 °C of 4.5 h, at 45 °C of 2.5 h, and at 50 °C of 1 h. Lineweaver–Burk plot showed Michaelis–Menten constant (Km: 3.14 mg/ml) and maximal velocity (Vmax: 1.428 mmol/ml/min) using casein. The actinidin activity was enhanced with Ca2+ while it was inhibited by Cd2+ and Hg2+ ions. The α-amylase protein was successfully inactivated upon incubation with actinidin for 30 min; around ~ 85% of the α-amylase activity diminished. IC50 for inhibition of α-amylase was 2.54 mg/ml for crude actinidin and 1.86 mg/ml for purified actinidin. Conclusions Purified Actinidin showed a 1.28-fold increase in proteolytic activity. The proteinase showed an active pH range of 3.5–8.5 under varied buffer conditions and thermostability up to 50 °C. The results revealed a significant potential utility of actinidin to retard amylase as it effectively degraded the amylolytic enzyme under in vitro conditions and could be beneficial for lowering glycemic response to ingested starch. However, further in vitro as well as in vivo studies need to be conducted under gastrointestinal conditions to establish the hypothesis.

Nursery practice in Dalbergia sissoo seedlings was performed in order to establish the efficacy of the rhizobial inoculants for future nurseries. The rhizospheric bacteria were isolated from different geographic locations of Himachal Pradesh and Uttrakhand. The nursery was set up by sowing the seeds collected from these locations. The rhizospheric bacterial inoculants isolated from D. sissoo rhizosphere were treated in the nursery for the establishment of a successful nursery. The nursery was observed for root, shoot parameters, and nodulation status showing variation in these characters with different geographic locations. From the same nursery, rhizobia were isolated from root nodules in YEMA media. Based on PGPR traits, two rhizobia, i.e., PGPR1 (DBD1) and PGPR2 (DRT5) were treated in the second nursery along with different levels of nitrogenous fertilizers. The consortium of PGPR1+PGPR2 was observed to be the best treatment that significantly increased the growth parameters, i.e., root, shoot parameters and nodulation status, and nitrogenase activity in D. sissoo seedlings.

Enzymes play vital roles in all organisms. The enzymatic process is progressively at its peak, mainly for producing biochemical products with a higher value. The immobilization of enzymes can sometimes tremendously improve the outcome of biocatalytic processes, making the product(s) relatively pure and economical. Carrier-free immobilized enzymes can increase the yield of the product and the stability of the enzyme in biocatalysis. Immobilized enzymes are easier to purify. Due to these varied advantages, researchers are tempted to explore carrier-free methods used for the immobilization of enzymes. In this review article, we have discussed various aspects of enzyme immobilization, approaches followed to design a process used for immobilization of an enzyme and the advantages and disadvantages of various common processes used for enzyme immobilization.