The present study focused on the evaluation of a nonspecific synergistic effect of biogenic silver nanoparticles (AgNPs) in combination with biosurfactants against environmental bacteria and fungi. The AgNPs were synthesized in the culture supernatants of the biosurfactant producer Bacillus subtilis grown in brewery effluent, molasses or Luria-Bertani media. Antibacterial activities were tested against Gram-positive and Gram-negative bacteria, while the antifungal activity was tested against phytopathogens. The interactions between biogenic AgNPs and DNA were investigated using a cryo-TEM technique. The presence of biosurfactant significantly increased the stability of biogenic AgNPs and enhanced their antimicrobial activities. The physical properties and antimicrobial activity of biogenic AgNPs were compared with chemically synthesized Ag nanoparticles. Biogenic silver nanoparticles showed a broad spectrum of activity against bacteria and fungi. They were most active against phytopathogenic fungi and Gram-positive bacteria and less active against Gram-negative bacteria. The nonspecific synergistic effect of biogenic AgNPs and biosurfactant on the phytopathogenic fungi was especially observed. In this report, the new roles of biosurfactants as a biogenic AgNPs stabilizer and enhancer of their antimicrobial properties are presented. Our results revealed that the biologically synthesized AgNPs by the biosurfactant-producing bacterium Bacillus subtilis grown on agro-industrial wastes, such as molasses and brewery effluent, could be used as a promising new nanoagent against microbes.

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A b s t r a c t A broad series of 4,5,6,7-tetrahalogenated benzimidazoles and 4-(1H-benzimidazol-2-yl)-benzene-1,3-diol derivatives was tested against selected bacteria and fungi. For this study three plant pathogens Colletotrichum sp., Fusarium sp., and Sclerotinia sp., as well as Staphylo coccus sp., Enterococcus sp., Escherichia sp., Enterobacter sp., Klebsiella spp. , and Candida spp. as human pathogens were used. MIC values and/or area of growth reduction method were applied in order to compare the activity of the synthesized compounds. From the presented set of 22 compounds, only 8, 16, 18 and 19 showed moderate to good inhibition against bacterial strains. Against Candida strains only compound 19 with three hydroxyl substituted benzene moiety presented high inhibition at nystatin level or lower.K e y w o r d s: antibacterial activity, antifungal activity, benzimidazole

This work is a continuation of research on Diaporthe genus isolates obtained in 2010−2012 from fruit trees in Poland, which on the basis of previously conducted molecular tests, have been identified as one species belonging to the Diaporthe eres species complex. The aim of this study was to determine the morphology and pathogenic abilities of tested Diaporthe eres isolates. The experiment included cross tests, in which the shoots of apple, pear, cherry and plum trees were inoculated with each of the 4 isolates derived from each mentioned host plants. As a result of experiment, the pathogenic nature of D. eres in relation to the shoots of fruit trees, was confirmed. The isolates were also characterized on the basis of the colony appearance and spore dimensions. Morphological features of studied D. eres cultures were very similar, regardless of the isolate and the host plant, from which they were obtained. All tested isolates formed alpha and beta conidia having the same range size.

The molecular characterization of Boeremia strasseri (Moesz) Gruyter et Verkley (basionym Phoma strasseri Moesz) isolates from peppermint crops grown in south-eastern and central Poland was studied using the Random Amplified Polymorphic DNA (RAPD) -PCR technique. Tests were performed using randomly selected primers. DNA profiles obtained using five primers proved to be useful in determining the genetic variability among B. strasseri genotypes. Molecular analysis of four loci: (i) rDNA internal transcribed spacer region (ITS1, 5.8S, ITS2); (ii) LSU (partial large subunit DNA 28S); (iii) tub 2 (gene region of βtubulin); (iv) act (gene region of gamma-actin) proved that the actin gene is the most suitable DNA barcode for the accurate and rapid identification B. strasseri species.

The effect of 15 fungi species most frequently inhabiting grapevine shoots on the growth of Phoma negriana was examined. Particular species-components of the fungal community were tested in vitro against the pathogen, using the biotic series method. The majority of fungi species inhibited P. negriana growth and the growth of only 3 species from the community, i.e. Alternaria alternata Keiss., Botrytis cinerea Pers. and Phomopsis viticola, was limited by the pathogen. Fungi Trichoderma were found the most effective against P. negriana. They completely degraded the hyphae and conidia of P. negriana after 20-22 days of growth in two-organism cultures. The summary biotic effects of fungal communities from grapevine were generally favourable to the P. negriana growth and only in one year of study they suppressed the pathogen development.

Genus Bacillus includes species of industrial, biotechnological, and environmental interest, as well as clinically important strains. In terms of metabolic properties, they present a diverse group, as they can degrade various substrates and produce many molecules, including lipopeptide (LP) biosurfactants. Due to a high interest in biosurfactants for application in different fi elds, the molecular mechanisms of regulation of the expression of the operons responsible for LPs have been intensively studied. Additionally, many assays have been created to evaluate the use of cost-effective renewable agro-industrial substrates for production. The purpose of the chapter is to provide a comprehensive overview of the results of our studies on identifi cation, characterization, and assessment ability of three Bacillus strains to produce biosurfactants and detection of genes encoding enzymes involved in biosurfactant synthesis. Moreover, the use of alternative substrates to decrease the cost of LP biosurfactant production and some aspects of application of Bacillus spp. as biocontrol agents are discussed.

Genetic variability within Septoria carvi isolates obtained from various organs of caraway cultivated in south-eastern and central Poland was studied using the RAPD-PCR technique. The tests were performed using randomly selected primers. The DNA profiles obtained using four primers proved useful in determining genetic variability among the genotypes of Septoria carvi isolates. The present study characterized the differences in the nucleotide sequence within the internal transcribed spacer region of rDNA (ITS1, 5.8S, ITS2) of selected S. carvi isolates and reference strains of Septoria spp. Moreover, eight isolates were sequenced for three loci: actin, calmodulin and translation elongation factor 1-alpha, and the obtained sequences were compared with the sequences of Septoria reference strains affecting other plants of the family Apiaceae. Phylogenetic analysis showed distinct differences of the tested isolates, which allowed to treat them Septoria carvi species affecting the above-ground organs of caraway Carum carvi L. This study is the first report on the genetic characteristics of the species S. carvi.