Biologically active polymers: synthesis and antimicrobial activity of modified glycidyl methacrylate polymers having a quaternary ammonium and phosphonium groups.

Polymers with antibacterial activity have been synthesized by chemical modification of poly(glycidyl methacrylate). The glycidyl methacrylate was polymerized by the free radical polymerization technique. The poly(glycidyl methacrylate) was hydrolyzed and was chloroacetylated using chloroacetyl chloride. The chloroacetylated product was modified to yield polymers with either quaternary ammonium or phosphonium salts. The antimicrobial activity of the modified glycidyl methacrylate polymers has been examined against a variety of test microorganisms by the cut plug and the viable cell counting methods using shake flask of ten times diluted nutrient broth medium. All three polymers obtained were inhibitory to the growth of Gram negative bacteria (Escherichia coli, Pseudomones aeruginosa, Shigella sp. and Salmonella typhae) and Gram positive bacteria (Bacillus subtilis and B. cereus) as well as the fungus (Trichophytun rubrum). It was found that the growth inhibitory effect varied according to the structure of the polymer and the composition of the active group and increased with increasing the concentration of the polymer. The tested polymers showed more antimicrobial activity against Gram negative bacteria and the fungus, whereas were less active against Gram positive bacteria.

Formation of tomatine in tomato plants infected with Streptomyces species and treated with herbicides, correlated with reduction of Pseudomonas solanacearum and Fusarium oxysporum f. sp. lycopersici.

Pretreatment of tomato seeds with pendimethalin or metribuzin and inoculation of seedlings with the antagonistic Streptomyces corchorusii or/and Streptomyces mutabilis were tested for the formation of tomatine in roots and stems of tomato, infested with Pseudomonas solancearum or/and Fusarium oxysporum f. sp. lycopersici. All treatments induced the formation of variable quantities of tomatine, compared with untreated control. The variation was proportional to: the pathogen, Fusarium was more stimulating than Pseudomonas; the antagonistic organism, S. corchorusii being more eliciting than S. mutabilis; the herbicide and its concentration, pendimethalin at 2 x 10(-3) M being the most eliciting of tomatine; and according to the soil, plants grown in non-sterilized soil accumulated more tomatine than did these grown in sterilized soil. In all treatments, stems had more tomatine than roots and non-sterilized soil was better than sterilized soil. The antagonistic streptomycetes induced accumulation of tomatine more than did the herbicides. The highest amounts of tomatine were detected in plants pretreated with pendimethalin at 2 x 10(-3) M, grown in non-sterilized soil, infested with F. oxysporum, and inoculated with S. corchorusii and S. mutabilis. The effect of the extracted tomatine on the growth of Fusarium and Pseudomonas was examined in vitro. The crude extract of tomatine from all treatments reduced growth and sporulation of F. oxysporum and growth of P. solanacearum in defined media. The reduction varied according to the treatment and was proportional to the quantities of extracted tomatine, the highest amounts being the most effective. The mechanism of phytoalexins in controlling tomato wilt pathogens was also discussed.

Optimal production conditions of an extracellular protease from Streptomyces corchorusii ST36.

Forty different isolates of streptomycetes from Egyptian soil were screened for their proteolytic activity in eight different media, for different time intervals and under different culture conditions. One of them, an isolate of Streptomyces corchorusi ST36 was the most active and glucose-aspartic acid-ammonium nitrate medium (GAA) was the best medium. Maximum production of the extracellular proteolytic activity by S. corchorusii ST36 (383 U/ml) was obtained at 30 degrees C after 5 days in shaked cultures. The optimal medium for maximum production of protease contained the soluble starch 2% (w/v), aspartic acid at 0.25% (w/v) and ammonium nitrate at 0.1% (w/v), at initial pH 6.0.

Protoplasts from the cyanobacterium,Spirulina platensis.

Protoplasts were obtained from the filamentous blue-green algaSpirulina platensis by treating the filaments with 0.05% (w/v) lysozyme in 0.03M phosphate buffer. The protoplasts regenerated cell walls and formed colonies when plated on a regeneration medium. The highest percentage of regeneration, 40% was obtained after 21 days.