Mária Mikulášová

Development of triclosan and antibiotic resistance in Salmonella enterica serovar Typhimurium

The possible association between the use of triclosan and the development of antibiotic resistance was examined in triclosan-resistant mutants of Salmonella enterica serovar Typhimurium. These mutants were obtained from a sensitive parental strain and from ciprofloxacin-resistant isogenic strains using spontaneous mutagenesis or selection after one short exposure or continuous exposure to low concentrations of triclosan. The results showed that triclosan in the environment does not increase the mutation frequency but selects bacterial strains with reduced antibiotic susceptibility. This property depended on the multiple antibiotic resistance (Mar) phenotype of bacterial strains and on the triclosan concentration.

Probiotic Potential and Safety Properties of Lactobacillus plantarum from Slovak Bryndza Cheese

One hundred and twenty-five acid-resistant presumptive lactobacilli were isolated from Slovak Bryndza cheese and screened for their antimicrobial activity against eight bacterial pathogens using spot agar assay. Out of twenty-six Lactobacillus strains with strong inhibition activity, twenty were identified as Lactobacillus plantarum and six as Lactobacillus fermentum. The most active eleven L. plantarum isolates were further characterized in vitro for some probiotic and safety properties. Only three isolates K10, K21, and ZS07 showed the ability to grow over 50% in the presence of 0.3% bile. Strong deconjugation efficiency was determined for CK06 and K21. The highest β-galactosidase activity was shown in isolates ZS11, B01, CK06, and ZS07. Only three of the strains had the ability to produce tyramine: CK06, LM1, and ZS11. Strains K09, K21, ZS11, and ZS15 were susceptible to all tested antibiotics. Analysis of the results confirmed the L. plantarum isolates ZS07 and K21 as the most suitable for probiotic use, due to their desirable probiotic and safety characteristics.

Influence of phenolics on biomass production by Candida utilis and Candida albicans

Abstract The effect of some lignin degradation products, which can be present in wood hydrolysates, on biomass production by Candida sp. was studied. Suspected inhibitors were used as supplements in growth media for C. utilis and C. albicans containing pure glucose as a carbon energy source. The metabolism of inhibitors by C. utilis and C. albicans is approximately the same and is extremely sensitive to the structure and concentration of the phenolic additive. ID50 and ID100 values for a 50% or a 100% growth inhibition for 20 lignin monomer model compounds during Candida sp. cultivation were established. Comparison of ID values has shown that the least toxic compounds for C. utilis and C. albicans biomass growth and yield are vanillyl alcohol, conipheryl alcohol and syringic acid. The most toxic compounds are salicylic acid, cinnamic acid, benzoic acid and o-vanillin.

In Vitro Antibacterial and Antibiotic Resistance Modifying Effect of Bioactive Plant Extracts on Methicillin-Resistant Staphylococcus epidermidis

The crude extracts of plants from Asteraceae and Lamiaceae family and essential oils from Salvia officinalis and Salvia sclarea were studied for their antibacterial as well as antibiotic resistance modifying activity. Using disc diffusion and broth microdilution assays we determined higher antibacterial effect of three Salvia spp. and by evaluating the leakage of 260 nm absorbing material we detected effect of extracts and, namely, of essential oils on the disruption of cytoplasmic membrane. The evaluation of in vitro interactions between plant extracts and oxacillin described in terms of fractional inhibitory concentration (FIC) indices revealed synergistic or additive effects of plant extracts and clearly synergistic effects of essential oil from Salvia officinalis with oxacillin in methicillin-resistant Staphylococcus epidermidis.

Genotoxic and antimutagenic activities of extracts from pseudocereals in the Salmonella mutagenicity assay.

Extracts of amaranth (Amaranthus L.), sorghum (Sorghum bicolor L.) and Japanese millet (Echinochloa frumentacea L.) were evaluated for mutagenicity in Salmonella typhimurium strains TA98, TA100 and TA102. All three pseudocereal extracts were also assessed for their antimutagenic properties against the direct mutagens 2-nitrofluorene (2NF) for strain TA98, 3-(5-nitro-2-furyl)acrylic acid (5NFAA) for TA100 and H(2)O(2) for TA102 strain and against the indirect mutagen aflatoxin B(1) (AFB(1)). No mutagenicity was induced by any of the pseudocereal extracts when tested at concentrations as high as 50mg/ml. All three extracts showed similar antimutagenicity against 5NFAA and no antimutagenicity against 2NF. The number of revertants induced by H(2)O(2) extract was inhibited in order amaranth>Japanese milet>sorghum. All extracts were effective in the inhibition of mutagenic activity of aflatoxin B(1). The total polyphenol content as well as the amount of the flavonoids and phenolic acids as main component of polyphenolics were also determined.

Reduction of carcinogenesis by bio-based lignin derivatives

Abstract The potential medicinal application of lignin component of biomass derived from chemical treatment of wood for paper production was examined with regard to its ability to bind N -nitrosoamines and bile acids. Correlation between adsorption affinity of lignins towards N -nitrosodiethylamine and their cross-linking density was revealed. In contrast to lignin, all the tested carbohydrate preparations were poor adsorbents. It was revealed that the most effective lignin adsorbents—modified kraft and prehydrolysis lignins inhibit mutagenicity and SOS response induced by 4-nitroquinoline- N -oxide. Moreover, these lignin preparations exhibited a protective effect on deoxyribonucleic acid (DNA) in hamster V79 cells and in human VH10 and Caco-2 colon carcinoma cells exposed to hydrogen peroxide (H 2 O 2 ) treatment due to their antioxidant nature. In the case of N -methyl- N ′-nitro- N -nitrosoguanidine—treatment lignins reduced alkylation of DNA due to their high affinity for adsorption of mutagenic N -nitroso compounds. This dual ability of lignin tested to decrease genotoxic activity of chemicals seems to be very promising for their application as natural antimutagenic and anticarcinogenic agents.

Effect of blending lignin biopolymer on the biodegradability of polyolefin plastics

The ability of the lignin-degrading microorganism Phanerochaete chrysosporium to attack polyethylene and polypropylene was investigated using a series of polymer blends containing 10, 20 and 30% lignin obtained from the waste product of pulp and paper industry. In the cultivation medium, lignin peroxidase and Mn(II)peroxidase activities were detected. Degradation was verified by quantitative u.v. spectrophotometric analysis of the cultivation medium and by liberation of CO2 from the blends. Measurement of the tensile strength after 30-days cultivation showed that the mechanical properties of the polymer blends were decreased during the biodegradation process. The isolation of oligomer fractions by tetrahydrofuran (THF) extraction of biodegraded polymers and their characterization by gel permeation chromatography (GPC), u.v. and Fourier transmission infrared (FTIR) spectroscopy indicates that biotransformation of the lignin component during the cultivation process initiates partial biodegradation of the synthetic polymer matrix.

Copper Complexes with Bioactive Ligands Part I -- Antimicrobial Activity

Biological properties of new copper(II) complexes of 2-methylthionicotinate (2-MeSNic) of composition Cu(2-MeSNic)2(MeNia)2·4H2O (where MeNia isN-methylnicotinamide), Cu(2-MeSNic)2(Nia)2·2H2O (where Nia is nicotinamide) and Cu(2-MeSNic)2(2 (where L is isonicotinamide (iNia) or ethyl nicotinate (EtNic)) are reported. Gram−-bacteria (Escherichia coli) are more resistant against Cu(II) complexes than Gram+-bacteria (Staphylococcus aureus)—significant antistaphylococcal activity was found with Cu(2-MeSNic)2(MeNia)2·4H2O (IC50 1.3 mmol/L).Caddida parapsilosis was most inhibited by Cu(2-MeSNic)2·H2O and Cu(2-MeSNic)2(MeNia)2·4H2O (IC50 1.4 mmol/L and 1.5 mmol/L, respectively). Biosynthesis of nucleic acids influenced by Cu(2-MeSNic)2-(Nia)2·2H2O indicated by incorporation of14C-adenine (IC50(Ade) 0.31 mmol/L) is more sensitive than biosynthesis of proteins indicated by incorporation of14C-leucine (IC50(Leu) 9.94 mmol/L). Cu(II) complexes with expressed antimicrobial activity showed no mutagenic activity.

Modulation of mutagenicity of various mutagens by lignin derivatives

The effect of lignin on cytotoxicity, mutagenicity and SOS response induced by 4-nitroquinoline-N-oxide (4NQO), 3-(5-nitro-2-furyl)acrylic acid (5NFAA), 2-nitrofluorene (2NF) as well as hydrogen peroxide was investigated in bacterial assay systems, i.e. the Ames test with Salmonella typhimurium TA98, TA100, TA102 and the SOS chromotest with Escherichia coli PQ37. Lignin preparations obtained from beech wood significantly decreased the mutagenicity induced by 4NQO, 2NF and H(2)O(2). In the case of mutagenicity induced by 5NFAA the effect was lower. Antimutagenic properties of lignin samples tested were shown also by SOS chromotest where lignin inhibited the ability of both 4NQO and H(2)O(2) to induce the SOS response. Derivatives of lignin including those from soft and hard wood, as well as from annual plants differ in their efficiency to inhibit the induction of the SOS response. The modified lignins isolated from beech and spruce wood exhibit a high level of protection. Lignins from annual plants-corn cobs and straw-only marginally evoked an antimutagenic response, but their effect was increased by hydrothermic treatment of both annual plants. The results obtained indicate the prospective utilization of lignin preparations as additive in chemo-prevention. The antimutagenic effect of lignin samples varies with the method of isolation and modification, as well as with the genetic origin of the lignin.

Biodegradability of lignin—Polypropylene composite films

Biological degradation of composite lignin-polypropylene films containing 4% organocell lignin was confirmed by treatment with lignin-degrading enzymes produced by the white-rot fungusPhanerochœte chrysosporium. The kinetics ofP. chrysosporium culture in the presence of lignin-containing and lignin-free polypropylene films show that the fungus produced lignin-degrading enzymes into the liquid medium during incubation with the lignin-polypropylene film. The degree of biodegradation of both types of film was followed by monitoring their mechanical properties. Correlation was found between the decrease of elongation at break and the amount of released lignin fragments into the extracellular fluid in the course of microbial treatment. The incorporation of lignin into polyolefins represents a new way of using wastes from pulp and paper industry to reduce the environmental impact factor of waste plastics.