Inactivation of endotoxin by Limulus amoebocyte lysate.

The inactivation of bacterial endotoxin by aqueous extracts (Limulus amoebocyte lysate) of the circulating blood cells (amoebocytes) of the horseshoe crab, Limulus polyphemus, is described. Active extracts were obtained by heating Limulus amoebocyte lystate (LAL) to 60°C for 20 min to denature the clotting enzyme, rendering the LAL incapable of gel formation in the presence of endotoxin. Endotoxin inactivation was assayed using the Limulus amoebocyte lysate test and by rabbit bioassay. Inactivation of endotoxin with heated extracts of LAL was suggestive of enzymatic mediation, as indicated by dependence on time, temperature, pH, and the kinetics of inactivation. Endotoxin inactivation occurred over a broad pH range, 4.5–8.5, with the optimum at a pH of 6.1. Temperature optima were between 37° and 50°C, with observed activity between 0° and 65°C. Ionized calcium was inhibitory to endotoxin inactivation with heated extracts of LAL, with partial inhibition at 0.001 m calcium and complete inhibition at 0.02 m calcium. Other divalent cations (Mg, Ba, Mn, and Cu) were also found to inhibit the inactivation of endotoxin. Similarities between the endotoxin-inactivating system of L. polyphemus and those described to be present in mammalian and lower vertebrate sera are discussed.     

Antimicrobial defense mechanisms in the horseshoe crab,Limulus polyphemus: Effect of sodium chloride on bactericidal activity

Bactericidal activity of heat-derived (60°C) extracts of Limulus amoebocyte lysate (LAL) was found to be inhibited by low molar (10 to 100 mm) concentrations of the monovalent cations Na⁺ and K⁺. The protective effect of Na⁺ was shown to be species dependent and inversely proportional to the sensitivity of the test microorganism as determined by bactericidal titer. The effect of Na⁺ (100 mm) on bactericidal activity in whole (unheated) LAL, when assayed against a sensitive species (Escherichia coli), was negligible and in direct contrast to data obtained when using 60°C extracts of LAL. Increasing the concentration of Na⁺ to reflect levels in L. polyphemus blood (400 to 500 mm) afforded only minimal protection for sensitive bacterial species. These data suggested that whole LAL may contain a heat-labile substance (protein?) capable of binding Na⁺, obviating the inhibitory effect of Na⁺ on bactericidal activity. Further evidence for the existence of this cation-binding substance was obtained when 55°C extracts of LAL were found refractory to Na⁺ concentrations which totally abolished bactericidal activity in 60°C extracts. The mechanism of Na⁺ inhibition of bactericidal activity and the role of the cation-binding substance in L. polyphemus host defense against bacterial invasion and dissemination is discussed.     

Antimicrobial activity and phytochemical analyses of Polygonum aviculare L. (Polygonaceae), naturally growing in Egypt

Polygonum aviculare (Polygonaceae) is an herb commonly distributed in Mediterranean coastal regions in Egypt and used in folkloric medicine. Organic and aqueous solvent extracts and fractions of P. aviculare were investigated for antimicrobial activities on several microorganisms including bacteria and fungi. Phytochemical constituents of air-dried powered plant parts were extracted using aqueous and organic solvents (acetone, ethanol, chloroform and water). Antimicrobial activity of the concentrated extracts was evaluated by determination of the diameter of inhibition zone against both Gram-negative and Gram-positive bacteria and fungi using paper disc diffusion method.Results of the phytochemical studies revealed the presence of tannins, saponins, flavonoids, alkaloids and sesquiterpenes and the extracts were active against both Gram-negative and Gram-positive bacteria. Chloroform extract gave very good and excellent antimicrobial activity against all tested bacteria and good activity against all tested fungi except Candida albicans. Structural spectroscopic analysis that was carried out on the active substances in the chloroform extract led to the identification of panicudine (6-hydroxy-11-deoxy-13 dehydrohetisane).Evaluation of the antimicrobial activity of panicudine indicated significant activity against all tested Gram-negative and Gram-positive organisms. Panicudine displayed considerable activity against the tested fungi with the exception of C. albicans. Antimicrobial activity of the extracts was unaffected after exposure to different heat treatments, but was reduced at alkaline pH. Studies of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of panicudine on the tested organisms showed that the lowest MIC and the MBC were demonstrated against Salmonella paratyphi, Bacillus subtilis and Salmonella typhi and the highest MIC and MBC were against Staphylococcus aureus.     

Monitoring the microbial contamination of beef carcass tissue with a rapid chromogenic Limulus amoebocyte lysate endpoint assay

A chromogenic Limulus amoebocyte lysate (LAL) endpoint assay was found to be an accurate and rapid means of gauging levels of beef carcass microbial contamination within 10 min. The assay demonstrated a high correlation with the total mesophilic bacterial and coliform surface populations from inoculated beef carcass surface tissues. This assay was tested on a set of actual beef carcass surface samples (n = 121) demonstrating the utility of the chromogenic LAL test as a means of monitoring carcass microbial contamination in a near real-time fashion. Classifying the chromogenic LAL results into four contamination groups was found to be a sound means of utilizing the resultant chromogenic LAL data for detecting carcasses with high levels of microbial contamination. For beef carcass testing, this assay can be used with no instrumentation other than the required 37 degrees C incubator and, as an option, a microplate reader.     

Isolation,Purification and Characterization of Antimicrobial Peptides Produced from <Emphasis Type="Italic">Saccharomyces boulardii</Emphasis>

Saccharomyces boulardii was used for antimicrobial peptides production. Separation process of produced antimicrobial peptides was conducted using ultrafiltration technique through dialysis membranes with porous 10 (MWCO) kDa. The inhibition activity was determined against four bacterial isolates. As a result, higher inhibition zone against Bacillus cereus were 26, 29 and 33 mm after adding 50, 75 and 100 µL of concentrated peptide, respectively. After that, peptide passed through the Sephadex G-50 column to achieve purified peptide using gel filtration. The high activity of purified peptide was confirmed based on the second peak reaching to 37 mm of bacterial inhibition zone while other peaks did not show any inhibition against tested bacteria. Some of the important characteristics of purified bioactive peptide were applied. Antimicrobial peptides stability was studied and found to be stable at pH range from 5 to 7 values studied in addition to its inhibition activity reached to 100%. Regarding thermal stability, it was observed that the peptide was fully activity at a both 60–80 °C for 30 min. Moreover, molecular weight of a peptide was identified using electrophoresis technique with SDS measured at 5792 Dalton.     

A comparative study of the bactericidal activity of horseshoe crab (Limulus polyphemus) hemolymph and vertebrate serum

This paper describes a partially heat-labile, naturally occurring bactericidal factor in cell-free hemolymph preparations obtained from Limulus polyphemus. This bactericidal activity has been shown to be directed against two Gram-negative bacteria, Escherichia coli and Klebsiella pneumoniae, whereas it had no effect on the Gram-positive bacteria tested, Micrococcus lysodeikticus and Staphylococcus aureus. Maximal bactericidal activity of this factor was observed at 30°C and pH 6.0. Since complement and antibody are required for antimicrobial activity in vertebrate sera, the activity of this factor in the presence of various complement inhibitors was assayed. The bactericidal activity of Limulus hemolymph is abolished by treatment with endotoxin; however, other anticomplementary substances were without effect. Limulus amebocyte lysate is known to contain protein which may be precipitated by endotoxin; it is possible that the reduction of bactericidal activity produced by endotoxin treatment may be caused by the denaturation of a bactericidal protein moiety produced by the hemocytes.     

Characterization of a heat stable anti-listerial bacteriocin produced by vancomycin sensitive Enterococcus faecium isolated from idli batter

Lactic acid bacteria (LAB) are known to produce various types of bacteriocins, ribosomally synthesized polypeptides, which have antibacterial spectrum against many food borne pathogens. Listeria monocytogenes, a pathogenic bacterium, is of particular concern to the food industry because of its ability to grow even at refrigeration temperatures and its tolerance to preservative agents. Some of the bacteriocins of LAB are known to have anti-listerial property. In the present study, the bacteriocin produced by vancomycin sensitive Enterococcus faecium El and J4 isolated from idli batter samples was characterized. The isolates were found to tolerate high temperatures of 60°C for 15 and 30 min and 70°C for 15 min. The bacteriocin was found to be heat stable and had anti-listerial activity. The bacteriocin did not lost anti-listerial activity when treated at 100°C for 30 min or at 121°C for 15 min. The bacteriocin lost its antimicrobial activity after treating with trypsin, protinase-K, protease and peptidase.     

Potentiation of antibiotic activity by Passiflora cincinnata Mast. front of strains Staphylococcus aureus and Escherichia coli

The development of new drugs from plants is an interesting alternative approach to overcoming microbial resistance. Passiflora cincinnata shows resistance to diseases and pests and a higher concentration of chemical components that may be useful in the pharmaceutical industry. We investigated the potential antimicrobial and antibiotic-modifying activity of hydroalcoholic extracts of leaves, stems, bark, pulp and seeds of P. cincinnata. The extracts were prepared by homogenization of material in 50% ethanol. Minimum inhibitory concentration (MIC) was determined by the broth dilution method, and the bacterial strains tested were Staphylococcus aureus and Escherichia coli. Antibiotic-modifying activity was evaluated against the strains S. aureus 03 and E. coli 08, using a subinhibitory concentration of extract. The antibiotics tested were: amikacin, gentamicin, ampicillin, potassium benzylpenicillin and oxacillin. The extracts did not show antimicrobial activity of clinical relevance, where the MIC was equal to or greater than 1024 μg/mL. S. aureus showed 13 events, while E. coli showed only 4 events. Among these events, 14 involved synergistic activity, potentiating the effect of the antibiotics, and only 3 events demonstrated antagonistic activity toward ampicillin. Hydroalcoholic extracts are potential antimicrobial agents when combined with conventional drugs little utilized in in vivo treatment.     

Antimicrobial activity of Calotropis procera Ait. (Asclepiadaceae) and isolation of four flavonoid glycosides as the active constituents

Antimicrobial activity of solvent extracts and flavonoids of Calotropis procera growing wild in Saudi Arabia was evaluated using the agar well-diffusion method. A bioassay-guided fractionation of the crude flavonoid fraction (Cf₃) of MeOH extract which showed the highest antimicrobial activity led to the isolation of four flavonoid glycosides as the bioactive constituents. Structure of compounds have been elucidated using physical and spectroscopic methods including (UV, IR, ¹H, ¹³C-NMR, DEPT, 2D ¹H–¹H COSY, HSQC, HMBC and NOESY). Compounds were found to be the 3-O-rutinosides of quercetin, kaempferol and isorhamnetin, besides the flavonoid 5-hydroxy-3,7-dimethoxyflavone-4′-O-β-glucopyranoside. Most of the isolated extracts showed antimicrobial activity against the test microorganisms, where the crude flavonoid fraction was the most active, diameter of inhibition zones ranged between 15.5 and 28.5 mm against the tested bacterial strains, while reached 30 mm against the fungal Candida albicans. The minimal inhibitory concentrations varied from 0.04 to 0.32 mg/ml against all of the tested microorganisms in case of the crude flavonoid fraction. Quercetin-3-O-rutinoside showed superior activity over the remainder flavonoids. The Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) were more susceptible than the Gram-negative (Pseudomonas aeruginosa and Salmonella enteritidis) and the yeast species were more susceptible than the filamentous fungi. The study recommend the use of such natural products as antimicrobial biorationals.     

In vitro antioxidant,antimicrobial and antiproliferative studies of four different extracts of Orthosiphon stamineus,Gynura procumbens and Ficus deltoidea

BackgroundMedicinal plants are important source of drugs with pharmacological activities. Therefore, there is always rising demands to discover more therapeutic agents from various species. Orthosiphon stamineus, Gynura procumbens and Ficus deltoidea are high valued medicinal plants of Malaysia contain rich source of phenolic and flavonoid compounds. The aims of the present study were to evaluate anti-oxidant, antimicrobial and anti-proliferative effects on A549, HePG2 and MCF7 cell lines of four different extracts of Orthosiphon stamineus, Gynura procumbens and Ficus deltoidea.MethodologyThe leaves of all selected plants were extracted with methanol, chloroform, ethyl acetate and butanol separately with simple cold maceration. Antioxidant activity of all crude extracts were quantitatively measured against DPPH and Ferric Reducing Assay. Antimicrobial evaluation was done by Microdilution and MTT assay and antipoliferative activity of all extracts of selected plant were evaluated against A549, HePG2 and MCF7 cell lines.ResultsResults showed that methanol extract exhibited highest percentage free radical scavenging activity of almost all extracts of selected plants. Antimicrobials results showed chloroform and methanol extracts of O. stamineus extract were the two most active extracts against resistant MRSA but not S. aureus. Only methanol extract of G. procumbens showed antimicrobial activity against the tested pathogens. Chloroform and methanol extracts of F. deltoidea elicited antimicrobial activity against S. aureus but not MRSA. Antiproliferative activity against three tested cell lines results showed that ethyl acetate extract of O. stamineus showed good effect whereas methanol extract of F. deltoidea and G. procumbens exhibited good antiproliferative activity.ConclusionsThe results of the present investigation demonstrated significant variations in the antioxidant, antimicrobial and antiproliferative effects of different solvent extracts. These data could be helpful in isolation of pure potent compounds with good biological activities from the extracts of plants.     

Antimicrobial and antioxidant activities with acute toxicity,cytotoxicity and mutagenicity of Cystoseira compressa (Esper) Gerloff & Nizamuddin from the coast of Urla (Izmir,Turkey)

The aim of the study was to evaluate the biological activities with toxic properties of the methanol, hexane, and chloroform extracts of Cystoseira compressa (Esper) Gerloff & Nizamuddin from the Coast of Urla in the Aegean Sea. The extracts of C. compressa were tested for their antimicrobial and antioxidant activities in this study. Cytotoxic and mutagenic potentials of the extracts were also evaluated using cell culture and mutagenicity assays. Hexane extract was found to have higher total flavonoid and phenolic contents than the other extracts and exerted higher antioxidant activity than other extracts. All extracts exhibited moderate antimicrobial activity against tested microorganisms (minimum inhibitory concentration ranges are 32–256 μg/mL). The results indicated that the extracts had no significant cytotoxic activity against human hepatocellular carcinoma Hep 3B cell line in all treated concentrations (5–50 μg/mL) and did not show mutagenicity in the Ames test. Lethality was not observed among mice treated with oral doses of the extracts. In conclusion, results of investigations indicate that brown alga C. compressa is a natural source of antioxidant. It has moderate antimicrobial activities with no toxicity.     

Synergistic Antimicrobial Activity of Camellia sinensis and Juglans regia against Multidrug-Resistant Bacteria

Synergistic combinations of antimicrobial agents with different mechanisms of action have been introduced as more successful strategies to combat infections involving multidrug resistant (MDR) bacteria. In this study, we investigated synergistic antimicrobial activity of Camellia sinensis and Juglans regia which are commonly used plants with different antimicrobial agents. Antimicrobial susceptibility of 350 Gram-positive and Gram-negative strains belonging to 10 different bacterial species, was tested against Camellia sinensis and Juglans regia extracts. Minimum inhibitory concentrations (MICs) were determined by agar dilution and microbroth dilution assays. Plant extracts were tested for synergistic antimicrobial activity with different antimicrobial agents by checkerboard titration, Etest/agar incorporation assays, and time kill kinetics. Extract treated and untreated bacteria were subjected to transmission electron microscopy to see the effect on bacterial cell morphology. Camellia sinensis extract showed higher antibacterial activity against MDR S. Typhi, alone and in combination with nalidixic acid, than to susceptible isolates.” We further explore anti-staphylococcal activity of Juglans regia that lead to the changes in bacterial cell morphology indicating the cell wall of Gram-positive bacteria as possible target of action. The synergistic combination of Juglans regia and oxacillin reverted oxacillin resistance of methicillin resistant Staphylococcus aureus (MRSA) strains in vitro. This study provides novel information about antimicrobial and synergistic activity of Camellia sinensis and Juglans regia against MDR pathogens     

The Diversity and Antimicrobial Activity of Preussia sp. Endophytes Isolated from Australian Dry Rainforests

Limited knowledge currently exists regarding species diversity and antimicrobial activity of endophytic isolates of Preussia within Australia. This report describes endophytic Preussia species that were identified through molecular analysis of the internal transcribed spacer region. Screening for antimicrobial secondary metabolites was determined by testing crude ethyl acetate (EtOAc) extracts derived from fungal mycelia against a panel of ATCC type strains which included Bacillus cereus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Serratia marcescens, methicillin-resistant Staphylococcus aureus (MRSA) and the opportunist yeast pathogen Candida albicans. Subsequently, high-performance liquid chromatography generated fractions of bioactive EtOAc extracts which were subject to confirmatory testing using the Clinical and Laboratory Standards Institute reference microdilution antimicrobial activity assay. A total of 18 Preussia were isolated from nine host plants with 6/18 having a <97 % sequence similarity to other known species in Genbank, suggesting that they are new species. In preliminary screening, 13/18 Preussia isolates revealed antimicrobial activity against at least one of the microbes tested, whilst 6/18 isolates, including 4/6 putative new species showed specific antimicrobial activity against MRSA and C. albicans. These results highlight the antimicrobial potential of Australian Preussia spp. and also the importance of Australian dry rainforests as an untapped repository of potentially significant bioactive compounds.     

Characterization of Antimicrobial Peptides Isolated from the Processing by-Products of African Catfish <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

Antimicrobial peptides (AMPs) as components of innate immunity system have been isolated from fish and other species. In this study, the crude proteins extracted with gradient ammonium sulfate precipitation technique from the processing by-products of African catfish Clarias gariepinus (C. gariepinus) were purified by size-exclusion chromatography and all the four obtained fractions, Clarias antimicrobial peptides I(CAP-I), CAP-II, CAP-III and CAP-IV, showed antimicrobial activity. Among of these fractions, CAP-IV showed the highest antimicrobial activity against Staphylococcus aureus, Aeromonas sobria, Aeromonas hydrophila, Escherichia coli by agar diffusion plate test and the diameter of inhibition zone was 8.34, 9.27, 6.76, 6.13 mm, respectively. The molecular weight of main peptides of CAP-IV was around 4.1 KD by SDS-PAGE analysis. CAP-IV showed antimicrobial activity against both gram-negative and gram-positive bacterial pathogens at minimum inhibitory concentrations (MICs) ranging from 105 to 420 μg/mL. The antimicrobial activity of CAP-IV was stable at wide pH range, 3–11 and was also heat-stable when temperature was below 80 °C. Freeze-thawing treatment also only had slight effects on the antimicrobial activity of CAP-IV. Besides, CAP-IV was not sensitive to the hydrolysis by pepsin and trypsin, except for protease K. These results suggest that CAP-IV isolated from C. gariepinus is potential to be developed as a new antimicrobial peptide and may partially explain the high disease resistance of African catfish C. gariepinus.     

ISOLATION AND CHARACTERIZATION OF CYANOBACTERIA POSSESSING ANTIMICROBIAL ACTIVITY FROM THE SUNDARBANS,THE WORLD’S LARGEST TIDAL MANGROVE FOREST1

Eight obligately halophilic, euryhaline cyanobacteria from intertidal soil were isolated in artificial seawater nutrients III (ASN‐III) medium. Antimicrobial activity, 16S rRNA gene sequences, phenotypic characters as well as growth and antibiosis in response to variable salinity, temperature, phosphate concentration, and pH were studied. Minimum inhibitory concentrations (MIC) of the extracts against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and multiple drug‐resistant clinical isolates ranged between 0.25 and 0.5 mg · mL⁻¹. Cytotoxicity tests showed 73%–84% human colon adenocarcinoma (HT‐29/C1) cell survival at MIC values, indicating that the extracts were nontoxic. Morphologically, six cyanobacteria were assigned to the Lyngbya‐Phormidium‐Plectonema (LPP) group B, and one each was assigned to Oscillatoria and Synechocystis genera. Glycerol, mannitol, and starch supported better photoheterotrophic growth than simpler mono‐ and disaccharides. No heterocyst formation was observed when grown under nitrogen‐starved conditions. All isolates survived 7‰ salinity, grew at minimum 32‰ salinity, and showed sustained growth throughout 32‰–82‰ salinity but matured poorly in freshwater medium supplemented with 30.0 g · L⁻¹ NaCl. Antimicrobial production occurred only at 32‰ salinity. While four of the eight isolates demonstrated sustained growth at 37°C, maximum antimicrobial activity was obtained at 25°C. All strains showed maximum growth and antimicrobial elaboration at 0.04 g · L⁻¹ phosphate. All isolates thrived at pH 9.5; six grew at pH 4.5, though antimicrobial production occurred only at pH 7.5. Molecular phylogenetic analysis based on 16S rRNA gene sequences of the filamentous isolates validated the previous taxonomic affiliations established on morphological characteristics. This is the first study of antimicrobial‐producing halophilic cyanobacteria from the mangroves.     

Activity of four antimicrobial cocktails for tissue allograft decontamination against bacteria and Candida spp. of known susceptibility at different temperatures

Several antimicrobial cocktail solutions of differing composition and concentrations are widely used to decontaminate viable banked tissue allografts at different temperatures and times of exposure. We compared the efficiency of four cocktails comprising nine antimicrobials to kill suspensions of a panel of 27 strains of 13 bacterial species, and 3 Candida spp. at 4, 22 and 37 °C for 24 h. All but one bacterial strains were susceptible to one or more of the agents tested individually at concentrations at least fourfold below the recommended susceptibility breakpoint minimum inhibitory concentrations for drug/species combinations. Candida lusitaniae was resistant to nystatin and amphotericin. The concentrations of several of the cocktail constituents were often greatly in excess (50–1,000-fold) of that required to inhibit the growth of susceptible strains. All cocktails were ineffective against a pan-resistant strain of Enterococcus faecium and one of the four cocktails failed to kill two strains of methicillin resistant Staphylococcus aureus. Each cocktail was most efficient at 37 °C, less so at 22 °C, and poorly active at 4 °C. We conclude that the practice of decontamination of tissues with antimicrobials at low temperatures is not supported by in vitro susceptibility tests.     

Dissociation between the interleukin 1-inducing capacity and Limulus reactivity of lipopolysaccharides from gram-negative bacteria

In this study we compared the interleukin 1 (IL 1)-inducing capacity and the reactivity in the Limulus amoebocyte assay (LAL) of purified lipopolysaccharides (LPSs) from various bacterial strains. LPSs differed greatly in their capacities (on a weight basis) to induce IL 1 release from serum-free cultured human monocytes. LPS species that induced high levels of IL 1 release from human monocytes exhibited a high thiobarbiturate-reactive 2-keto-3-deoxy-octonic acid (KDO) content. No relationship was found between the IL 1-inducing activity and the LAL reactivity of purified LPSs. Filtration experiments in which membranes of decreasing size-exclusion limits were used demonstrated that molecular species of LPS with an apparent Mr below 3,000 may induce IL 1, whereas only species with an apparent Mr above 8,000 are recognized in the LAL assay. The latter observation suggests that the reaction with LAL requires an aggregated form of LPS. These results indicate that biologically active LPS species can cross dialysis membranes in vivo although no LAL reactive material is detected in the blood compartment. The Limulus assay is an insufficient criterion for the absence of LPS in biological fluids.     

Anti-listerial Bactericidal Activity of Lactobacillus plantarum DM5 Isolated from Fermented Beverage Marcha

The strain Lactobacillus plantarum DM5 was isolated from fermented beverage Marcha of Sikkim and explored for its antagonistic activity against food-borne pathogens. The cell-free supernatant of L. plantarum DM5 showed antibacterial activity of 6,400 AU/mL in MRS medium (pH 6.0) against the indicator strain Staphylococcus aureus. MRS medium supplemented with 15 g/L of maltose at 37 °C under static condition yielded highest antimicrobial activity (6,400 AU/mL) with 3 % increase in specific activity when compared to 20 g/L glucose. The antimicrobial compound was heat stable (60 min at 100 °C) and was active over a wide pH range. It showed bactericidal effect on S. aureus and Listeria monocytogenes by causing 96 and 98 % of cell lysis, respectively. The cell morphology of the treated S. aureus and L. monocytogenes was completely deformed as revealed by scanning electron microscopy, suggesting the high potential of L. plantarum DM5 as natural preservatives in food industry. The antimicrobial compound was purified by 80 % ammonium sulphate precipitation and showed antimicrobial activity of 12,800 AU/mL with 19-fold purification and a molecular mass of 15.2 kDa, indicating the proteinaceous nature of the compound.     

Antimicrobial activities of extracts of Cyperus rotundus L. rhizomes against some bacterial and fungal pathogens of strawberry and tomato

Antimicrobial activities of rhizome extracts of Cyperus rotundus were investigated on selected plant pathogenic bacteria and fungi. Ethyl acetate and hexane extracts showed antibacterial activity against three isolates of Clavibacter michiganensis subsp. michiganensis at concentrations of 900 and 1000 μg/ml. However, Gram-negative bacterial pathogens of tomato; Pseudomonas syringae pv. tomato and Ralstonia solanacearum were not inhibited from the extracts. Ethyl acetate extracts at 100 μg/ml inhibited mycelial growth and spore germination of the two strawberry isolates of Botrytis cinerea; however, no significant inhibition was found in tomato fungal pathogen, Fusarium oxysporum f. sp. radicis lycopersici. Minimum inhibitory concentrations were determined as 0.0625 and 0.125 mg/ml against C. michiganensis subsp. michiganensis for ethyl acetate and hexane extracts of rhizomes, respectively. This study shows the potentials of extracts of C. rotundus rhizomes as antimicrobial agents that are effective against the tested plant pathogenic bacteria and fungi.