Isolation and identification of protease‐producing bacteria from sludge and sediment soil around Adama, Ethiopia

Proteases are enzymes used in industries such the production and processing of detergents, food, leather, and silk. The aim of this study was to isolate and identify protease‐producing bacteria from a sludge disposal site and from sediments. Soil samples were collected separately from the selected area. Samples weighing 1 g were serially diluted and spread onto skim milk agar. A total of 16 bacteria species were isolated from the study samples. Four bacterial isolates showed high proteolytic activity and were selected for enzymatic study based on their zone of proteolysis. The isolates were identified based on biochemical tests. The results indicated that the isolated bacteria were E. coli (99.69%), Pseudomonas putrefaciens (Shewanella putrefaciens) (91.61%), Bacillus carboniphilus (92.78%), and Lysinibacillus sphaericus (98.4%). The crude protease enzymes produced by these bacterial isolates showed promising results for application in dehairing and destaining as detergent additives. Bacillus carboniphilus showed the best level of activity and was selected as the most potent protease‐producing bacteria for both dehairing and destaining ability. Soils from sludge disposal sites and sediments from around tannery wastes could be good sources from which to isolate alkaline protease‐producing bacteria.

Production of Bio-Fertilizer through Composting of Tannery Wastes with CowDung and Rice Bran

Tannery waste is made from nutrients and organic compounds that enhance soil fertility thereby improving plants and microbial growths. This study was designed to investigate the application of tannery wastes to form compost material in a mixture with cow-dung and rice brand. The treatments were prepared and tested for a period of sixty (60) days. The compost was characterized by electric conductivity (EC) of 10.11µs/cm, pH of 7.62 and Carbon-Nitrogen (C:N) ratio of 28.8. Total concentrations of Chromium, Lead, Cadmium, Copper, Zinc and Iron in mg/kg were 57.2, 0.92, 12.50, 60.50, 13.60 and 1101.00 respectively. However, total bacterial counts decreased from 8.2 x108 cfu/g to 1.8 x106 cfu/g after the 60days. The compost characteristics indicate about 80% germination index which may suggest the removal of most of the phototoxic compounds. Key words: Composting, Tannery wastes, bio-fertilizer

Transglutaminase Crosslinked Gelatin Films Extracted from Tanned Leather Waste

The production of biodegradable polymers has proved to be a promising alternative, since these materials have accelerated degradation, contributing to the reduction of residues and the reduction of environmental pollution. The tannery wastes contain considerable collagen and can be used for gelatin extraction and film production for use in agriculture. Gelatin-based films, however, present some challenges for practical application, such as permeability and solubility in water, parameters that can be improved through the crosslinking process by employing enzymes, promoting the union of polymeric gelatin chains. In this context, the action of the enzyme transglutaminase was investigated to improve the properties of gelatin films recovered from leather and chitosan residues, which were evaluated according to thickness, solubility, permeability, mechanical properties, and soil degradation. The results indicated that the enzyme concentration in the films had a significant effect on the properties of water permeability and solubility and strain to rupture. The evaluation of soil degradation showed that films with higher enzyme addition took longer to be degraded.