Isolation of Maize Soil and Rhizosphere Bacteria with Antagonistic Activity against Aspergillus flavus and Fusarium verticillioides

2007 ◽  
Vol 70 (7) ◽  
pp. 1615-1621 ◽  
Author(s):  
JEFFREY D. PALUMBO ◽  
TERESA L. O'KEEFFE ◽  
HAMED K. ABBAS
Keyword(s):  
Aspergillus Flavus ◽  
Extracellular Enzymes ◽  
Fusarium Verticillioides ◽  
Enteric Bacteria ◽  
Antagonistic Activity ◽  
Bacterial Strains ◽  
Antifungal Metabolites ◽  
Maize Field ◽  
Simultaneous Control ◽  
Agar Media

Bacterial isolates from Mississippi maize field soil and maize rhizosphere samples were evaluated for their potential as biological control agents against Aspergillus flavus and Fusarium verticillioides. Isolated strains were screened for antagonistic activities in liquid coculture against A. flavus and on agar media against A. flavus and F. verticillioides. We identified 221 strains that inhibited growth of both fungi. These bacteria were further differentiated by their production of extracellular enzymes that hydrolyzed chitin and yeast cell walls and by production of antifungal metabolites. Based on molecular and nutritional identification of the bacterial strains, the most prevalent genera isolated from rhizosphere samples were Burkholderia and Pseudomonas, and the most prevalent genera isolated from nonrhizosphere soil were Pseudomonas and Bacillus. Less prevalent genera included Stenotrophomonas, Agrobacterium, Variovorax, Wautersia, and several genera of coryneform and enteric bacteria. In quantitative coculture assays, strains of P. chlororaphis and P. fluorescens consistently inhibited growth of A. flavus and F. verticillioides in different media. These results demonstrate the potential for developing individual biocontrol agents for simultaneous control of the mycotoxigenic A. flavus and F. verticillioides.

Antagonistic activity of Bacillus subtilis strains isolated from various sources

2018 ◽  
Vol 8 (2) ◽  
pp. 354-364
Author(s):  
A. N. Irkitova ◽  
A. V. Grebenshchikova ◽  
A. V. Matsyura
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Wild Strain ◽  
Fish Farming ◽  
Antagonistic Activity ◽  
Antagonistic Effect ◽  
E Coli ◽  
Long Period ◽  
Test Culture ◽  
Agar Media

<p>An important link in solving the problem of healthy food is the intensification of the livestock, poultry and fish farming, which is possible only in the adoption and rigorous implementation of the concept of rational feeding of animals. In the implementation of this concept required is the application of probiotic preparations. Currently, there is an increased interest in spore probiotics. In many ways, this can be explained by the fact that they use no vegetative forms of the bacilli and their spores. This property provides spore probiotics a number of advantages: they are not whimsical, easily could be selected, cultivated, and dried. Moreover, they are resistant to various factors and could remain viable during a long period. One of the most famous spore microorganisms, which are widely used in agriculture, is <em>Bacillus subtilis</em>. Among the requirements imposed to probiotic microorganisms is mandatory – antagonistic activity to pathogenic and conditional-pathogenic microflora. The article presents the results of the analysis of antagonistic activity of collection strains of <em>B. subtilis</em>, and strains isolated from commercial preparations. We studied the antagonistic activity on agar and liquid nutrient medias to trigger different antagonism mechanisms of <em>B. subtilis</em>. On agar media, we applied three diffusion methods: perpendicular bands, agar blocks, agar wells. We also applied the method of co-incubating the test culture (<em>Escherichia coli</em>) and the antagonist (or its supernatant) in the nutrient broth. Our results demonstrated that all our explored strains of <em>B. subtilis</em> have antimicrobial activity against a wild strain of <em>E. coli</em>, but to varying degrees. We identified strains of <em>B. subtilis</em> with the highest antagonistic effect that can be recommended for inclusion in microbial preparations for agriculture.</p><p><em><br /></em><em></em></p>

scholarly journals Antifungal activities of thiosemicarbazones and semicarbazones against mycotoxigenic fungi

2014 ◽  
Vol 38 (6) ◽  
pp. 531-537 ◽  
Author(s):  
Rojane de Oliveira Paiva ◽  
Lucimar Ferreira Kneipp ◽  
Carla Marins Goular ◽  
Mariana Almeida Albuquerque ◽  
Aurea Echevarria
Keyword(s):  
Antifungal Activity ◽  
Aspergillus Flavus ◽  
Fungicidal Activity ◽  
Fusarium Verticillioides ◽  
Animal Health ◽  
Fungistatic Activity ◽  
Mycotoxigenic Fungi ◽  
Quality Of Food ◽  
Chelating Effect

Mycotoxigenic fungi can compromise the quality of food, exposing human and animal health at risk. The antifungal activity of eight thiosemicarbazones (1-8) and nine semicarbazones (9-17) was evaluated against Aspergillus flavus, A. nomius, A. ochraceus, A. parasiticus and Fusarium verticillioides. Thiosemicarbazones had MIC values of 125-500 µg/ml. The thiosemicarbazones 1 and 2 exerted fungistatic activity against Aspergillus spp., and thiosemicarbazone 2 exerted fungicidal activity against F. verticillioides. Compound 2 showed an iron chelating effect of 63%. The ergosterol content of A. parasiticus had a decrease of 28 and 71% for the 31.2 and 62.5 µg/ml concentrations of thiosemicarbazone 2 compared to the control. The obtained results of antifungal activity revealed that thiosemicarbazone class was more active when compared to semicarbazone class and, the thiosemicarbazone 2 was the most active compound, specially, against Aspergillus spp.

scholarly journals Antimicrobial Activity of Coriander sativum

2021 ◽  
pp. 74-81
Author(s):  
Samina Amin Qurban Ali ◽  
Arif Malik
Keyword(s):  
Antimicrobial Activity ◽  
Antioxidant Activity ◽  
Essential Oils ◽  
Aspergillus Flavus ◽  
Food Additives ◽  
Inhibition Zone ◽  
Microbial Pathogens ◽  
Bacterial Strains ◽  
High Concentration ◽  
Natural Oils

The increasing rate of drug-repellent pathogens and poisonousness of existing antiseptic compounds has strained attention toward activity of antimicrobial products which are natural. Main purpose of this research was to assess antimicrobial activity of seeds and leaves of Coriandrum sativum’s essential oil, antioxidant, antimicrobial activity and chemical composition of Coriandrum sativum’s ethanol extracts and essential oils. Numerous approaches were used in reviewing the antioxidant activity such as, p-anisidine test – malonaldhyde, DPPH and peroxide value. Antimicrobial activity of the extracts towards six microbial strains; two bacterial strains (Salmonella typhi and Staphylococcus aureus), one yeast (Candida tropicals) and three fungal strains (Aspergillus flavus, Mucor sp and Emericella nidulans) was assessed by determination of inhibition zone and count of bacteria, yeast and spares of fungus. The antimicrobial mechanisms found in these essential oils have been explained on the basis of their content in natural compounds such as carvacrol, thymol, p-cymene and c-terpinene, among others. Although these two essential oils have received much attention, scientists working in the fields of biomedicine and food science are paying increasing attention to a wider variety of aromatic natural oils in an effort to identify original and natural applications for the inhibition of microbial pathogens. In conclusion, utilization of coriander or their components as food additives will increase the antioxidant and the antimicrobial potential of the food which prevent food deterioration and improve the shelf-life of food beside its nutritional value. The results revealed that the leaves extracts have high levels of phenolics than the seeds extract. Concerning antioxidant activity, significant decreases (p>0.001) were observed in peroxide, P- anisidine and TBA values as compared to control oil. On the other hand, scavenging activity % of the four extracts on DPPH radical were higher than that of butylated hydroxyl toluene (BHT) especially with high concentration (1000 μg/ ml). Regarding antimicrobial activity, the results showed that the extract of coriander seeds has the highest reduction percent in growth of all the examined microorganisms. The result also revealed that Mucor sp was resistant to the action of parsley extracts while Aspergillus flavus has the highest resistance against coriander extracts.

scholarly journals Searching for Antagonistic Activity of Bacterial Isolates Derived from Food Processing Environments on Some Food-Borne Pathogenic Bacteria

2020 ◽  
Vol 49 (4) ◽  
pp. 415-423
Author(s):  
B. Baráti-Deák ◽  
Cs. Mohácsi-Farkas ◽  
Á. Belák
Keyword(s):  
Escherichia Coli ◽  
Food Processing ◽  
Pathogenic Bacteria ◽  
Inhibitory Effect ◽  
Antagonistic Activity ◽  
Bacterial Isolates ◽  
Bacterial Strains ◽  
Food Borne ◽  
Time Period ◽  
Growth Decline

Bacterial strains with inhibitory effect on Salmonella Hartford, Listeria monocytogenes, Yersinia enterocolitica, and Escherichia coli, respectively, were isolated. Out of the 64 bacteria originated from food processing environments, 20 could inhibit at least one of the tested pathogens, and it was proved that growth decline of the pathogenic bacteria was more remarkable by co-culturing than by using cell-free supernatants of the isolates. Seven different genera (Pseudomonas, Bacillus, Paenibacillus, Macrococcus, Staphylococcus, Serratia, and Rothia) reduced the pathogens’ growth during the time period of analysis, and the strongest inhibitory effect was observed after 24 h between 15 and 30 °C. Sensitivity of the tested human pathogenic bacteria against the inhibitory strains was distinct, as Y. enterocolitica could be inhibited by numerous isolates, while S. Hartford proved to be the most resistant. Our results reveal that the isolated bacteria or their excreted metabolites could hinder pathogen growth when used in sufficient quantities.

scholarly journals Novel Psychrophiles and Exopolymers from Permafrost Thaw Lake Sediments

2020 ◽  
Vol 8 (9) ◽  
pp. 1282
Author(s):  
Ilaria Finore ◽  
Adrien Vigneron ◽  
Warwick F. Vincent ◽  
Luigi Leone ◽  
Paola Di Donato ◽  
...  
Keyword(s):  
Extracellular Enzymes ◽  
Extreme Environments ◽  
Rrna Gene ◽  
Bacterial Strains ◽  
Ice Melt ◽  
Permafrost Thaw ◽  
Phenotypic And Genetic Characterization ◽  
Pseudomonas Extremaustralis ◽  
Commercial Polymers ◽  
Thaw Lakes

Thermokarst lakes are one of the most abundant types of microbial ecosystems in the circumpolar North. These shallow basins are formed by the thawing and collapse of ice-rich permafrost, with subsequent filling by snow and ice melt. Until now, permafrost thaw lakes have received little attention for isolation of microorganisms by culture-based analysis. The discovery of novel psychrophiles and their biomolecules makes these extreme environments suitable sources for the isolation of new strains, including for potential biotechnological applications. In this study, samples of bottom sediments were collected from three permafrost thaw lakes in subarctic Québec, Canada. Their diverse microbial communities were characterized by 16S rRNA gene amplicon analysis, and subsamples were cultured for the isolation of bacterial strains. Phenotypic and genetic characterization of the isolates revealed affinities to the genera Pseudomonas, Paenibacillus, Acinetobacter,Staphylococcus and Sphingomonas. The isolates were then evaluated for their production of extracellular enzymes and exopolymers. Enzymes of potential biotechnological interest included α and β-glucosidase, α and β-maltosidase, β-xylosidase and cellobiohydrolase. One isolate, Pseudomonas extremaustralis strain 2ASCA, also showed the capability to produce, in the loosely bound cell fraction, a levan-type polysaccharide with a yield of 613 mg/L of culture, suggesting its suitability as a candidate for eco-sustainable alternatives to commercial polymers.

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