Crude extracts of three actinomycetes species belonging to Saccharopolyspora (TR 046 and TR 039) and Actinosynnema (TR 024) genera were screened for antibacterial activities against a panel of several bacterial strains. The extracts showed antibacterial activities against both gram-negative and gram-positive test bacteria with inhibition zones ranging from 8 to 28 mm (TR 046); 8 to15 mm (TR 039); and 10 to 13 mm (TR 024). The minimum inhibitory concentrations ranged from 0.078 to 10 mg/mL (TR 046); 5 to >10 mg/mL (TR 039); and 1.25 to 5 mg/mL (TR 024). Time-kill studies revealed that crude extract of TR 046 showed strong bactericidal activity against Bacillus pumilus (ATCC14884), reducing the bacterial load by 10⁴ cfu/mL and 10² cfu/mL at 4× MIC and 2× MIC, respectively, after 6 h of exposure. Similarly, against Proteus vulgaris (CSIR 0030), crude extract of TR 046 achieved a 0.9log₁₀ and 0.13log₁₀ cfu/mL reduction at 5 mg/mL (4× MIC) and 1.25 mg/mL (2× MIC) after 12 h of exposure. The extract was however weakly bactericidal against two environmental bacterial strains (Klebsiella pneumoniae and Staphylococcus epidermidis); and against Pseudomonas aeruginosa (ATCC 19582): the extract showed bacteriostatic activities at all concentrations tested. These freshwater actinomycetes appear to have immense potential as a source of new antibacterial compound(s).

This study evaluated the potential use of proteases produced by Erwinia chrysanthemi for the extraction of pure chitin from crustacean wastes using standard methods. The crude bacterial protease had activity of 22.4 U/ml. Protein removal by the commercial protease were similar in both the mineralized and demineralized wastes and amounted to about 75 and 80%, respectively, in 16 h. A similar trend was observed with higher protein removal efficiency (95%) for the crude protease from both the mineralized and demineralized wastes. Also, treatment of the powder with 5% NaOH resulted in the removal of protein in the demineralized and mineralized wastes decreased by about 96 and 87.6%, respectively, in same period from an initial concentration of 0.3 mg/ml. It was concluded that proteases produced by E. chrysanthemi could be used to transform waste from sea-food processing industries into products of commercial value. Key words: Erwinia chrysanthemi, extra cellular, proteases, chitin, value-added products.

Whole cells of the phytopathogenic Erwinia chrysanthemi strains were immobilized in k-carrageenan and grown in high-calcium Xanthomonas campestris medium containing sodium polypectate as carbon source. All the strains used survived immobilization into k-carrageenan beads. Immobilized E. chrysanthemi strains displayed higher pectolytic and proteolytic enzyme activities than free cells in liquid suspension. Carrageenan immobilization techniques could provide a system to mimic the conditions of E. chrysanthemi cells in the infected plant tissue. This could prompt a thorough study of the factors governing the biosynthesis of virulence factors by this bacterium. Journal of Industrial Microbiology & Biotechnology (2001) 27, 215–219.