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Broad spectrum antimicrobial agents are urgently needed to fight frequently occurring multidrug-resistant pathogens. Myxobacteria have been regarded as “microbe factories” for active secondary metabolites, and therefore, this study was performed to isolate two bacteriolytic genera of myxobacteria, Myxococcus sp. and Corallococcus sp., from 10 soil/sand samples using two conventional methods followed by purification with the aim of determining the antimicrobial activity of methanol extracts against 11 test microorganisms (four Gram-positive, four Gram-negative, two yeasts and one fungus). Out of thirty-nine directly observed strains, 23 were purified and analyzed for antimicrobial activities. Based on the broth microdilution method, a total of 19 crude extracts showed antimicrobial activity. The range of inhibited wells was more important in the case of anti-Gram-positive-bacterial activity in comparison with the anti-Gram-negative-bacterial and antifungal activity. In light of the established degree and range of antimicrobial activity, two of the most active isolates (BNEM1 and SFEC2) were selected for further characterization. Morphological parameters and a sequence similarity search by BLAST revealed that they showed 99% sequence similarity to Myxococcus xanthus − BNEM1 (accession no. KX669224) and Corallococcus coralloides - SFEC2 (accession no. KX669225). As these isolates had antimicrobial activity, they could be considered for use in the development of antibiotics for pharmaceutical use.

This study aimed to evaluate the antifungal activity and the potential synergistic activity of ten plant extracts (EXs) and ten essential oils (EOs) obtained from the same plant species, namely Agrimonia eupatoria L., Arctium lappa L., Arnica montana L., Bidens cernua L., Corylus avellana L., Echinacea purpurea L. (Moench), Menta piperita L., Trifolium pratense L., Syzygium aromaticum L., and Angelica sinensis (Oliv.) Diels were used. Three species of the genus Candida, namely C. albicans, C. glabrata, and C. tropicalis, isolated from polluted estuarine water, were used in this study. The chemical composition of all EOs was evaluated by gas chromatography coupled with mass spectrometry (GC–MS) and gas chromatography with flame ionization detector (GC–FID) analysis. Firstly, the susceptibility of Candida spp. strains to EXs and EOs was screened by the agar disc diffusion method. Then the minimum inhibitory concentration (MIC) of the tested EXs and EOs was determined in a concentration range from 256 to 0.125 µL/mL. Following that, the effective EXs and EOs were divided into two groups (strong effect and weak effect) and tested in combination (strong + weak) at various concentrations depending on the tested strain to determine their potential synergistic effect using the chessboard pattern. The most sensitive strain to treatments with EXs and EOs tested alone and in mixtures was C. albicans. The most potent combinations with other EXs/EOs were observed with Syzygium aromaticum L., for both plant extract and essential oil, respectively. In this study the EOs and EXs tested in combination were much more effective than when acting on the growth of Candida spp. separately. So, the synergistic effect of the combinations of the EXs and EOs can lead to a reduction in the doses of commercial antifungals and can provide an effective way to reduce the infections caused by yeasts of the genus Candida. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the antagonistic effect of three strains of the genus Bacillus on toxigenic fungi contaminating food commodities, with emphasis on two ochratoxigenic isolates (A. ochraceus, A. westerdijkiae) and two aflatoxigenic isolates (A. flavus and A. parasiticus). In vitro studies were carried out using two different methods for cultivation tested bacilli with fungal isolates - coincubation and dual culture method. The most sensitive isolate was A. ochraceus by both used methods. B. mycoides (5.72 ± 6.4 mm) and B. subtilis (5.08 ± 2.84 mm) were able to inhibit its growth and sporulation during ten days of cultivation (both inhibited the sporulation of A. ochraceus 100%) in coincubation. The most effective in the dual culture method were B. subtilis and B. thuringiensis against A. ochraceus (growth inhibition rate 84.40%; 90.55%) and A. flavus (growth inhibition rate 91.54%; 92.43%). The most effective sporulation inhibitors were B. subtilis and B. thuringiensis, which completely inhibited the sporulation of A. ochraceus and A. parasiticus after ten days of coincubation. Likewise, all tested bacterial strains showed complete inhibition of ochratoxin A synthesis in A. ochraceus and A. westerdijkiae exposure to bacterial volatiles. So, the current study illustrated that strains of the genus Bacillus could significantly inhibit the growth, sporulation, and mycotoxin production of toxigenic aspergilli and showing the great potential as a biocontrol agent of preand post-harvest food diseases caused by microscopic filamentous fungi. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microbiological investigation of unexplored ecosystems is crucial for discovering of antibiotic producing actinomycetes. The present study was conducted to determine antimicrobial activity and identify the most active strains. Actinomycetes were isolated using the spread plate technique following by serial dilution of samples on starch casein agar. The screening method consists of primary and secondary testing. The most active isolates were identified based on molecular and cultural methods. 42 out of 66 isolates displayed antimicrobial potential. 63% exhibited antibacterial activity, 16% antifungal activity, and 16% displayed both activities. Identified isolates, Streptomyces scabrisporus , Streptomyces sparsogenes , Streptomyces misakiensis , Streptomyces cirratus , Streptomyces lincolnensis , Streptomyces endophyticus , Streptomyces chartreusis , and Streptomyces alboniger showed a broad spectrum of enzymatic activities. The results indicated that these isolates may serve as antibiotic and enzyme-producing microbes., Competing Interests: There are no conflicts of interest.