Identification and Characterization of a Protease Producing Bacillus cereus Strain From Tannery Waste for Efficient Dehairing of Goat Skin.

Abstract

Environmental pollution has been a significant concern for the last few years. The leather industry significantly contributes to the economy but is one of Bangladesh's most prominent polluting industries. It is also responsible for several severe diseases such as cancer, lung diseases, and heart diseases of leather workers because they use bleaching agents and chemicals, and these have numerous adverse effects on human health. The study was aimed at isolating, identifying, and molecularly characterizing bacteria that produce protease enzymes that are highly capable of dehairing goat hide. Several attempts were made to isolate and identify protease-producing bacterial strains from different soil samples of tannery wastes. Initially, a total of four isolates were selected from tannery soil. After the different phenotypic and morphological characterization, one isolate (BS2) showed Gram-positive, rod-shaped, and spore-forming characteristics and could produce novel hair-degrading protease enzymes. The growth profile and protease activity of the bacteria at 37°C were observed; a basal level of extracellular protease increased with time. The enzyme's proteolytic activity was measured, and the unit of enzyme activity of the enzyme sample was 18.1. The ExPASy server (ProtParam) tool was used to estimate the physicochemical characteristics of the proteins and found molecular weight (MW) (7375.94 Da), aliphatic index (71.56), instability index (II, 80.63), Grand Average of Hydropathy (GRAVY) (-0.231), and isoelectric point (11.41). The protein-protein interactions (PPI) networks were generated using the Search Tool for the Retrieval of Interacting Genes (STRING) database and Cytoscape software. The PSIPRED v.4.0 and SAVES v.6.0 programs were used to determine the secondary and three-dimensional assembly of the selected protein. They found alpha helix (16, 25.00%), extended strand (6, 9.38%), beta-turn (5, 7.81%), and random coil (37, 57.81%). DNA isolation and purification were carried out, and the purity ratio was ~2.17 at 260 and 280 nm. Polymerase chain reaction (PCR) for amplifying the 16S rRNA gene was conducted, and the isolate was authentically recognized as Bacillus cereus (BS2) based on morphological, biochemical, and molecular analyses. The quantitative assessment has shown that 40 mL of culture centrifugation could dehair 2 × 1 cm of goat leather sample in 9 h. This potential bacterial strain can be used in the leather industry as an ecofriendly alternative to chemical dehairing, which can reduce environmental pollution and the risk of severe diseases among leather industry workers.