Minimum Biocidal Concentration Research Articles

Antimicrobial and antioxidant activities of Indian gooseberry and galangal extracts

The antimicrobial and antioxidant activities of Indian gooseberry ( Phyllanthus emblica Linn.) and galangal ( Alpinia galanga) extracts were investigated. Two different methods (disc diffusion and agar dilution methods) were employed to evaluate the antimicrobial activities of plant extracts against Staphylococcus aureus. The minimum inhibitory concentration (MIC) values of Indian gooseberry and galangal extracts were found to be 13.97 and 0.78 mg/ml and the minimum biocidal concentration (MBC) values were 13.97 and 2.34 mg/ml, respectively. The antioxidant activities of Indian gooseberry and galangal extracts, which were evaluated by the β-carotene bleaching method, were 86.4% and 70.3%, respectively. The total phenolic contents of Indian gooseberry and galangal extracts, as determined by the Folin–Ciocalteu method, were 290.4±0.7 and 40.9±0.2 mg/g plant extract (in GAE), respectively. The GC–MS analysis showed that the main compounds of galangal extract are 1,8-cineole (20.95%), β-bisabolene (13.16%), β-caryophyllene (17.95%) and β-selinene (10.56%). On the other hand, the use of high-performance liquid chromatography (HPLC) with UV detection indicated many compounds within the Indian gooseberry extract.

Microbiological effects of olive mill waste addition to substrates for Pleurotus pulmonarius cultivation

When olive mill wastes (OMWs) and vegetation waters (VWs) obtained during the manufacture of olive oil were added as substrate supplements for the cultivation of Pleurotus pulmonarius the material modified growth of the mushroom and the endemic microbiota of the substrate, in particular the mushroom-pathogenic bacterium Pseudomonas tolaasii, which is responsible for bacterial blotch disease in mushrooms. VW addition to substrates, at up to 30% (v/w), did not interfere with mycelial growth, but inhibited fruit body formation. Supplementation at up to 10% did not inhibit pinhead appearance and reduced Ps. tolaasii-related symptoms. In an attempt to identify the compounds responsible for the observed reduction of symptoms, products of acidic, basic or enzymic hydrolysis of oleuropein, together with OMW ethyl acetate extracts and several single compounds, were studied. OMW ethyl acetate extracts and hydroxytyrosol inhibited Ps. tolaasii growth, but did not show bactericidal activity. Only 4-methylcatechol and catechol were effective as bactericides against Ps. tolaasii (minimum biocidal concentration 5 and 10 mM, respectively). Such concentrations were not reached if the wastes were added at 10% v/w; at such levels growth of the bacteria will only be inhibited, not eliminated completely.

Antimicrobial Activities Of Methanolic Extracts Of <i>Trema guineensis</i> (Schumm And Thorn) And <i>Morinda lucida</i> Benth Used In Nigerian

Extracts obtained from the leaves, stem-bark and roots of two ethnomedicinal plants: Morinda lucida Benth and Trema guineensis Schumm and Thorn were screened for antimicrobial activities against eleven test organisms (five bacteria and six fungi) namely: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Bacillus subtilis, Candida albicans, Trichopyton tonsurans, T. rubrum, T. mentagrophytes, Basidobolus haptosporus and Aspergillus niger . The agar plate, cup-plate and broth dilution methods were used for the antimicrobial analysis. The minimal inhibitory concentrations (MIC) and the minimum biocidal concentrations (MBC) of the extracts were determined in vitro.The results showed that most of these extracts posses in vitro antimicrobial activities against the tested clinical isolates of bacteria and fungi. These antimicrobial activities have been attributed to the presence of some or all of the following secondary plant metabolites: alkaloids, tannins, saponins, flavonoids, steroids and glycosides. Key Words: Plant extracts, antimicrobial activities, medicinal plants, methanol. Bio-Research Vol.2(1) 2004: 39-46

Anti-microbial activities of protic ionic liquids with lactate anion

Minimum inhibitory concentrations (MIC) and minimum biocidal concentrations (MBC) were established for 1-alkylimidazolium and 1-alkoxymethylimidazolium lactates tested against rods, cocci and fungi. We found that anti-microbial activities of the protic ionic liquids are strongly related to the length of the substituent and to the DL- or L-type anion. Lactates with short substituents up to pentyl or pentyloxymethyl remain inactive toward microorganisms. In addition physical properties and thermal stability of protic ionic liquids have been described. We found them to readily undergo decomposition under the effect of ozone in aqueous solution.

New Ionic Liquids with Organic Anions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Adsorption—desorption effect of microcrystalline cellulose on ampicillin and amoxycillin

Three grades of microcrystalline cellulose (Avicel PH 105, 103 and 102) were used to elucidate their effects on both ampicillin monohydrate and amoxycillin trihydrate, both in water and in 0.1 N HCl media. The studies were undertaken to determine the effect of specific surface area, pH as well as the type of antibiotic on the adsorptive capacity of microcrystalline cellulose. In addition, desorption of the antibiotics from the adsorbate was carried out in distilled water and in 0.1 N HCl solution at various elution stages. The minimum inhibitory concentration (MIC) and minimum biocidal concentration (MBC) were determined against the standard sensitive test microorganism ( Sarcina lutea ATCC 9341) for each of the selected antibiotics in absence and presence of each of the microcrystalline cellulose grades. Studies revealed that the smaller the particle size of microcrystalline cellulose the more drug was adsorbed, a property which is more apparent in aqueous ampicillin solution while amoxycillin was highly adsorbed in acid solution. Higher rates of antibiotic elution were obtained in acid solutions than in aqueous media. Amoxycillin showed higher elution relative to ampicillin to the extent of complete desorption in gastric pH solution. The MIC of the tested antibiotics increased in presence of microcrystalline cellulose with decreased particle size.

In vitro susceptibility of spiroplasmas to heavy-metal salts.

The susceptibility of six spiroplasma strains to heavy-metal salt was characterized in terms of minimal inhibitory concentrations and minimal biocidal concentrations in broth tube dilution tests. The strains were most susceptible to mercuric chloride and silver nitrate; less susceptible to copper sulfate, cobalt chloride, lead nitrate, and cadmium sulfate; and least susceptible to nickel chloride and zinc sulfate. Spiroplasma citri strains Maroc R8A2 and C189 were the most susceptible to five of eight heavy-metal salts, and honeybee spiroplasma strain AS576 and Spiroplasma floricola strain 23-6 were generally the least susceptible. The difference between the minimal biocidal concentrations and the minimal inhibitory concentrations was greater for certain heavy-metal salts than for others.

Mechanism of action of EM 49, membrane-active peptide antibiotic.

EM 49 (recently renamed octapeptin) is a membrane-active peptide antibiotic that has been reported to affect the structure of bacterial membranes (K. S. Rosenthal, P. E. Swanson, and D. R. Storm, Biochemistry 15:5783-5792, 1976). In this study, it is shown that the effects of EM 49 on bacterial metabolism are similar to those of uncouplers of oxidative phosphorylation. EM 49 stimulated bacterial respiration within a narrow concentration range corresponding to minimum inhibitory concentrations and inhibited respiration at concentrations comparable to minimum biocidal concentrations. In addition, the peptide increased membrane proton permeability and lowered the adenosine 5'-triphosphate pool size. Parallel studies done with the related antibiotic polymyxin B demonstrated that the two peptides differed considerably in their effects on bacterial respiration. In contrast to EM 49, polymyxin B did not stimulate respiration at any concentration. It is proposed that the primary action of EM 49 is to disrupt the selective ion permeability of the cytoplasmic membrane, thereby relaxing the membrane potential.