Laboratory and greenhouse experiments were conducted to assess the efficacy of Eucalyptus citriodora, Ipomoea carnea, Cuminum cyminum, Allium sativum and Hyoscyamus muticus leaf extracts, and Streptomyces exfloliatus (S) and Trichoderma harzianum (T) for controlling Botrytis fabae causing chocolate spot disease of faba bean. Laboratory study supported the use of E. citriodora (Ex 1 ) and I. carnea (Ex 2) extracts than the others for controlling the growth of B. fabae. S+Twas the best for inhibiting spore germination followed by Ex 1 +Ex 2 after 8 h of testing, whereas Ex 1 +Ex 2 produced the lowest percent of germination after 16 h. After 4 days, the inhibiting order of the growth of B. fabae was S+T > Ex 1 +Ex 2 > T > Ex 2 > Ex 1 = S. Greenhouse experiments showed the highest activities of peroxidase, catalase and pectinase in the infected plants. These activities were markedly reduced in healthy plants and widely changed by the biocontrol treatments. Applying biocontrol agents to the infected plants increased minerals (N, P, K and Mg), and both Chl biosynthesis and the photosynthetic activity, which in turn led to accumulation of metabolites. This served the plant to resist the detrimental effects of B. fabae on the plant growth and yield. In this concern, the efficiency of test biocontrol agents seemed to be in the order: T+S > Ex 1 +Ex 2 > T > S > Ex 2 > Ex.

Polymeric antimicrobial agents represent a new and important direction that is developing in the field of antimicrobial agents. Antimicrobial activity of two newly synthesized polymers: a modified poly (methylmethacrylate-co-vinylbenzoylchloride) and a modified linear poly (chloroethylvinylether-co-vinylbenzoylchloride) have been investigated and found to be active. Both polymers have showed a broad antimicrobial activity against C. albicans and C. tropicalis. Minimal inhibitory concentrations (MIC's) for poly (methylmethacrylate-co-vinylbenzoyl chloride) were 100, 75 and 100 microg/ml in case of C. albicans (ATCC 2091), C. albicans (SC5314) and C. tropicalis, respectively. However, polycholoroethylvinylether-covinylbenzoylchloride inhibited C. albicans (ATCC 2091), C. albicans (SC5314) and C. tropicalis with minimum inhibitory concentration values (MIC's) of 150 microg/ml against the three tested Candida strains. Mode of action studies of both polymers on the medically important yeasts, C. albicans and C. tropicalis revealed that poly (methylmethacrylate-co-vinylbenzoylchloride) induced cytotoxicity, DNA damage, and altered cell permeability and morphology, which was manifested as aggregated and swollen yeast cells (C. albicans ATCC 2091) by fluorescent microscopy examination. Poly (chloroethylvinylether-co-vinylbenzoylchloride) increased cell permeability, and respiration for C. albicans and C. tropicalis. The tested polymers at 50 microg/ml had pronounced effects on C. albicans and C. tropicalis cell wall phosphopeptidomannane, proteins, sugars and phosphorus. Generally, the two polymers proved effective against the tested microorganisms, but growth inhibitory effect varied according to the composition of the polymer active group. Many investigators consider polymeric antimicrobial agents as a potential new approach for enhancing the efficiency of some existing antimicrobial agents, including prolonged activity, reduce their toxicity, as well as reduce the environmental issues associated with product use.

Lake Bardawil represents a hyper-saline shallow (50-600 cm deep) water basin lying along the northern shore of Sinai. Surface water samples were collected monthly from this lake for physico-chemical and microbiological analysis. Seasonal variations in the averages of temperature, pH and transparency of the tested water samples were determined. Seasonal averages of the total bacterial counts at 22 and 37°C, biovolumes of cells and bacterial biomass of the lake's water at different regions were also determined. In addition to the gram-negative pathogen, Edwardsiella tarda, faecal contamination indicators, total coliforms, faecal coliforms and faecal streptococci were counted in the lake's water samples from various regions during different seasons. The number of actinomycetes per milliliter of the lake's water samples were determined. Fifteen actinomycetes were isolated and screened for their antibacterial activity against E. coli and pathogenic E. tarda isolated from the same water samples. Five isolates of these actinomycetes showed antibacterial activities and nine of them were identified as Streptomyces. The most antibacterially active isolate was subjected to morphological, physiological and biochemical studies and identified as Streptomyces viridiviolaceus. The identified organism exhibited antimicrobial activities against the main indicator of water pollution, E. coli, pathogenic E. tarda, Corynebacterium michiganese B-33, Pseudomonas solanacearum B-3212 and Staphylococcus. No antimicrobial activities were recorded against Bacillus cereus, Micrococcus, Mycobacterium, Aspergillus niger, Candida albicans, C. tropicalis or Rhizopus nigricans.

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