Biosorption potential and molecular characterization of metal resistant autochthonous microbes from tannery solid waste

This study encompasses isolation and screening of heavy metal-resistant fungal and bacterial strains from tannery solid waste (TSW). Twelve fungal strains and twenty-five bacterial strains were isolated from TSW. The growth of fungal strains was observed against different heavy metals ranging from 10 mg L -1 to 1050 mg L -1 and the growth of bacteria was observed in metal concentrations ranging from 10 mg L -1 to 1200 mg L -1 . Five multi-metal resistant fungal isolates belonging to the genus Trichoderma and ten bacterial isolates belonging to the genus Bacillus showed good metal resistance and biosorption potential. They were identified through molecular techniques, fungi based on ITS region ribotyping, and bacteria based on 16S rRNA ribotyping. The fungal strains were characterized as T. hamatum (TSWF-06), T. harzianum (TSWF-11), T. lixii (TSWF-02) and T. pseudokoningii (TSWF-03, TSWF-10). The bacterial strains were characterized as Bacillus xiamenensis (TSW-02), B. velezensis (TSW-05), B. piscis (TSW-06), B. safensis (TSW-10), B. subtilis (TSW-14, TSW-15, TSW-17) B. licheniformis (TSW-19), B. cereus (TSW-20) and B. thuringiensis (TSW-22). The fungal strains namely, T. pseudokoningii (TSWF-03) and T. harzianum proved to be two multi-metal resistant strains with good biosorption efficiency. Unlike fungi, bacterial strains showed metal specific resistance. The strains Bacillus xiamenensis , B. subtilis (TSW-14) and B. subtilis (TSW-15) showed good biosorption efficiency against Cr, B. safensis against Cu, B. piscis and B. subtilis (TSW-17) against Pb and B. licheniformis and B. thuringiensis against Zn. The autochthonous fungal and bacterial strains can therefore be employed to clean metal contaminated environments.

Tannery Solid Waste into Wealth by Non-Edible Gelatin Production from Raw Trimmings

During the conversion of raw hides or skins into leather involves generation of enormous amount of solid waste which has been major concern for environment and cause detrimental effect on it. In leather industry solid wastes can be generated almost from all operations including pre-tanning, tanning, and even post tanning operation. Solid wastes are mainly raw trimmings, fleshing, chrome shaving, buffing dust, keratin, finished scraps etc. The economic development of a country depends on the utilization of indigenous raw materials and their by-products. This paper focuses on utilization of raw trimmings into useful product like non edible gelatin those demand is going up day by day due to its versatile application in various fields. Raw trimmings are mainly originated during sorting of leather before actual tanning process happens and best for non- edible gelatin production as it does not contain any harmful chemicals. This study will also describe the chemical properties of gelatin, gelatin manufacturing process, manufacturing parameters from the leather wastes like raw trimmings. Optimum extraction of non-edible gelatin from raw trimmings found at 75-85ₒC for 12 hours in slightly basic condition. This study found that huge amount of raw trimmings which generally thrown directly to environment can serve as potential raw materials for the manufacture of non-edible as well as edible gelatin.