Isolation of Pure Cultures from Mixed Cultures: A Modern Approach

A Veillonella species and Enterococcus durans were isolated from the cecal contents of adult broilers. Mixed cultures of Veillonella and E. durans inhibited the growth of Salmonella typhimurium and Escherichia coli 0157:H7 on media containing 2.5% lactose (w/v). The growth of S. typhimurium or E. coli 0157:H7 was not inhibited by mixed cultures containing Veillonella and E. durans on media containing only 0.25% lactose or by pure cultures of Veillonella or E. durans on media containing either 0.25% or 2.5% lactose. The mixed cultures of Veillonella and E. durans produced significantly (P<0.05) more acetic, propionic, and lactic acids in media containing 2.5% lactose than in media containing 0.25% lactose. The inhibition of the enteropathogens was related to the production of lactic acid from lactose by the E. durans and the production of acetic and propionic acids from lactic acid by the Veillonella.

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Chemical preservatives in foodstuffs VI. The effect of silver ions on microbes, in particular on the flora of fresh fish

Agricultural and Food Science ◽

10.23986/afsci.71664 ◽

1966 ◽

Vol 38 (4) ◽

pp. 198-209

Author(s):

Olavi E. Nikkilä ◽

Alpo Siiriä ◽

Jorma J. Laine

Keyword(s):

Aqueous Solution ◽

Silver Ions ◽

Mixed Cultures ◽

Fresh Fish ◽

Baltic Herring ◽

Pure Cultures ◽

Chemical Preservatives

A study has been made of the effect of silver ions upon microbes in water, in rinsing and washing experiments, and in the storage of fresh Baltic herring in ice containing silver ions. It was observed that silver ions were microbicidic in all experiments except in those with stored fish. Even in this case, silver ions were effective in killing bacteria when they were isolated and kept in an aqueous solution. In all the experiments the pure cultures were less resistant than the natural mixed cultures.

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N2O producing capability of nitrosomonas europaea, nitrobacter winogradskyi and alcaligenes faecalis

Water Science & Technology ◽

10.2166/wst.1997.0360 ◽

1997 ◽

Vol 36 (10) ◽

pp. 65-72 ◽

Cited By ~ 10

Author(s):

Yuhei Inamori ◽

Xiao-Lei Wu ◽

Motoyuki Mizuochi

Keyword(s):

Nitrosomonas Europaea ◽

Alcaligenes Faecalis ◽

N2o Emission ◽

Mixed Cultures ◽

Ammonia Oxidizer ◽

Experimental Conditions ◽

N2o Production ◽

Pure Cultures ◽

Pva Gel ◽

Different Cultures

Nitrosomonas europaea, Nitrobacter winogradskyi and Alcaligenes faecalis—typical ammonia-oxidizer, nitrite-oxidizer and heterotrophic nitrifier were immobilized in PVA gel and employed in the study. Continuous experiments were conducted in their pure and mixed cultures with DO concentrations in the cultures kept at 4, 2, 0.5 mg·l−1. Comparisons among N2O emission from different cultures were made to show their N2O producing capabilities. Results showed that: compared with N. europaea and A. faecalis, N. winogradskyi produced negligible N2O. On the other hand, N. europaea had the highest N2O producing ability. Unit N. europaea produced N2O 18–53 times higher than unit A. faecalis did. However, due to the higher population of A. faecalis, N2O production of the A. faecalis culture was higher than that of the N. europaea culture when DO concentration in the cultures was 2 mg·l−1; whereas, N2O yields of the A. faecalis culture were smaller than those of the N. europaea culture at DO concentrations of 4 and 0.5 mg·l−1. N2O emitted from most the mixed cultures was lower than that from pure cultures under the experimental conditions.

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Bioleaching of Low-Grade Copper Sulfide Ore Using a Colum Reactor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.71-73.409 ◽

2009 ◽

Vol 71-73 ◽

pp. 409-412

Author(s):

Wen Qing Qin ◽

Yan Sheng Zhang ◽

Shi Jie Zhen ◽

Jun Wang ◽

Jian Wen Zhang ◽

...

Keyword(s):

Iron Concentration ◽

Mixed Cultures ◽

Copper Recovery ◽

Low Grade ◽

Leaching Rate ◽

Ministry Of Education ◽

Copper Ore ◽

Copper Leaching ◽

Pure Cultures ◽

Mixed Bacteria

The effects of several variables on the column bioleaching of copper sulphide ore have been investigated. The copper ore contained chalcopyrite as the main sulfide minerals and bornite and chalcocite as the minor minerals. The experiment was carried out using bench-scale column leach reactors designed in Key Lab of Biometallurgy of Ministry of Education, which were inoculated with the pure mesophile bacteria (Acidithiobacillus ferrooxidans) and thermophile bacteria (Sulfobacillus), respectively, and the mixed bacteria which contain both iron- and sulfur-oxidizing bacteria. The results show that the mixed cultures were more efficient than the pure cultures alone and the maximum copper recovery 53.64% was achieved using the mixed cultures after 85 days. The leaching rate of chalcopyrite tended to increase with the increased dissolved ferric iron concentration. The effect of particle size on the rate of the copper leaching was also investigated, and it was shown that the copper bioleaching rate decreases as the amount of fines increase, which limits the permeability, thus decreases leaching rate. Jarosite and elemental sulphur formed in the column were characterized by the X-ray and EDS.

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Studies in intermicrobial symbiosis. Saccharomyces cerevisiae and Lactobacillus casei

Canadian Journal of Microbiology ◽

10.1139/m72-269 ◽

1972 ◽

Vol 18 (11) ◽

pp. 1733-1742 ◽

Cited By ~ 89

Author(s):

R. D. Megee III ◽

J. F. Drake ◽

A. G. Fredrickson ◽

H. M. Tsuchiya

Keyword(s):

Saccharomyces Cerevisiae ◽

Continuous Culture ◽

Mixed Culture ◽

Growth Medium ◽

Lactobacillus Casei ◽

Mixed Cultures ◽

Genetic Characteristics ◽

Culture Techniques ◽

Pure Cultures

Saccharomyces cerevisiae and a riboflavin assay strain of Lactobacillus casei have been propagated anaerobically in mixed culture. Both batch and continuous culture techniques were used. By varying the concentrations of glucose and riboflavin in the growth medium, it was possible to produce symbioses of commensalism + competition, competition, and mutualism + competition. In short, the interaction prevailing is determined by the medium as well as by the genetic characteristics of the organisms. The behavior of the mixed cultures in these situations was predicted from data taken on pure cultures of the organisms.

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Increase in the in vitro susceptibility of Staphylococcus aureus to antimicrobial agents in the presence of Candida albicans

Canadian Journal of Microbiology ◽

10.1139/m79-066 ◽

1979 ◽

Vol 25 (4) ◽

pp. 429-435 ◽

Cited By ~ 2

Author(s):

J. deRepentigny ◽

R. Lévesque ◽

L. G. Mathieu

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Candida Albicans ◽

Inhibitory Activity ◽

Antimicrobial Agents ◽

Mixed Cultures ◽

Alpha Toxin ◽

In Vitro Susceptibility ◽

Pure Cultures

In experiments with mixed cultures of Staphylococcus aureus and Candida albicans both in the absence and in the presence of 5-fluorocytosine (5-FC), we have observed that (1) there is an inhibition of S. aureus growth in mixed cultures with C. albicans in media supplemented with 1 μg/mL of 5-FC and that 5-FC has no effect on staphylococci in pure cultures; (2) this inhibition occurred with clinically isolated and laboratory strains and could be reversed by specific metabolites; (3) Staphylococcus aureus was inhibited by filtrates of C. albicans cultures treated with 5-FC and this seemed to be favored by some C. albicans filterable product which can affect the cell wall and the permeability of the staphylococcal cells since they become sensitive to 5-FC; (4) nine other commonly used antimicrobials showed an increased inhibitory activity against S. aureus in mixed cultures with C. albicans; and (5) there is a decrease in the number of precipitating antigens of S. aureus and of the activity of alpha toxin when this species was grown with both C. albicans and 5-FC. Our results indicate that the susceptibility of some species to antimicrobials could be significantly modified in the presence of other species. One cannot exclude that a similar phenomenon could happen in hosts under treatment with antibiotics against infection.

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In Vitro Activity of Trovafloxacin against Bacteroides fragilis in Mixed Culture with either Escherichia coli or a Vancomycin- Resistant Strain of Enterococcus faecium Determined by an Anaerobic Time-Kill Technique

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.45.1.243-251.2001 ◽

2001 ◽

Vol 45 (1) ◽

pp. 243-251 ◽

Cited By ~ 16

Author(s):

Lorna E. T. Stearne ◽

Clarissa Kooi ◽

Wil H. F. Goessens ◽

Irma A. J. M. Bakker-Woudenberg ◽

Inge C. Gyssens

Keyword(s):

Escherichia Coli ◽

Resistant Strain ◽

Enterococcus Faecium ◽

Mixed Cultures ◽

E Coli ◽

Abdominal Abscesses ◽

Pure Cultures ◽

Vancomycin Resistant ◽

Time Kill

ABSTRACT To determine the efficacy of trovafloxacin as a possible treatment for intra-abdominal abscesses, we have developed an anaerobic time-kill technique using different inocula to study the in vitro killing ofBacteroides fragilis in pure culture or in mixed culture with either Escherichia coli or a vancomycin-resistant strain of Enterococcus faecium (VREF). With inocula of 5 × 105 CFU/ml and trovafloxacin concentrations of ≤2 μg/ml, a maximum observed effect (E max) of ≥6.1 (log10 CFU/ml) was attained with all pure and mixed cultures within 24 h. With inocula of 108CFU/ml, a similar E max and a similar concentration to produce 50% of E max(EC50) for B. fragilis were found in both pure cultures and mixed cultures with E. coli. However, to produce a similar killing of B. fragilis in the mixed cultures with VREF, a 14-fold increase in the concentration of trovafloxacin was required. A vancomycin-susceptible strain of E. faecium and a trovafloxacin-resistant strain of E. coli were also found to confer a similar “protective” effect on B. fragilis against the activity of trovafloxacin. Using inocula of 109 CFU/ml, the activity of trovafloxacin was retained for E. coli and B. fragilis and was negligible against VREF. We conclude that this is a useful technique to study the anaerobic killing of mixed cultures in vitro and may be of value in predicting the killing of mixed infections in vivo. The importance of using mixed cultures and not pure cultures is clearly shown by the difference in the killing of B. fragilis in the mixed cultures tested. Trovafloxacin will probably be ineffective in the treatment of infections involving large numbers of enterococci. However, due to its ability to retain activity against large cultures of B. fragilis and E. coli, trovafloxacin could be beneficial in the treatment of intra-abdominal abscesses.

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Enhanced Removal of a Pesticides Mixture by Single Cultures and Consortia of Free and ImmobilizedStreptomycesStrains

BioMed Research International ◽

10.1155/2013/392573 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 31

Author(s):

María S. Fuentes ◽

Gabriela E. Briceño ◽

Juliana M. Saez ◽

Claudia S. Benimeli ◽

María C. Diez ◽

...

Keyword(s):

Mixed Culture ◽

Pure Culture ◽

Immobilized Cells ◽

Mixed Cultures ◽

Ex Situ ◽

Antagonistic Effects ◽

Pure Cultures

Pesticides are normally used to control specific pests and to increase the productivity in crops; as a result, soils are contaminated with mixtures of pesticides. In this work, the ability ofStreptomycesstrains (either as pure or mixed cultures) to remove pentachlorophenol and chlorpyrifos was studied. The antagonism among the strains and their tolerance to the toxic mixture was evaluated. Results revealed that the strains did not have any antagonistic effects and showed tolerance against the pesticides mixture. In fact, the growth of mixed cultures was significantly higher than in pure cultures. Moreover, a pure culture (Streptomycessp. A5) and a quadruple culture had the highest pentachlorophenol removal percentages (10.6% and 10.1%, resp.), whileStreptomycessp. M7 presented the best chlorpyrifos removal (99.2%). Mixed culture of allStreptomycesspp. when assayed either as free or immobilized cells showed chlorpyrifos removal percentages of 40.17% and 71.05%, respectively, and for pentachlorophenol 5.24% and 14.72%, respectively, suggesting better removal of both pesticides by using immobilized cells. These results reveal that environments contaminated with mixtures of xenobiotics could be successfully cleaned up by using either free or immobilized cultures ofStreptomyces, throughin situorex situremediation techniques.

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Staphylococcus aureus Virulence Expression Is Impaired by Lactococcus lactis in Mixed Cultures

Applied and Environmental Microbiology ◽

10.1128/aem.02388-08 ◽

2009 ◽

Vol 75 (13) ◽

pp. 4459-4472 ◽

Cited By ~ 48

Author(s):

Sergine Even ◽

Cathy Charlier ◽

Sébastien Nouaille ◽

Nouri L. Ben Zakour ◽

Marina Cretenet ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Lactococcus Lactis ◽

Stress Responses ◽

Time Lag ◽

Defined Medium ◽

Mixed Cultures ◽

Constant Ph ◽

Pure Cultures ◽

Cellular Machinery ◽

Short Time

ABSTRACT Staphylococcus aureus is responsible for numerous food poisonings due to the production of enterotoxins by strains contaminating foodstuffs, especially dairy products. Several parameters, including interaction with antagonistic flora such as Lactococcus lactis, a lactic acid bacterium widely used in the dairy industry, can modulate S. aureus proliferation and virulence expression. We developed a dedicated S. aureus microarray to investigate the effect of L. lactis on staphylococcal gene expression in mixed cultures. This microarray was used to establish the transcriptomic profile of S. aureus in mixed cultures with L. lactis in a chemically defined medium held at a constant pH (6.6). Under these conditions, L. lactis hardly affected S. aureus growth. The expression of most genes involved in the cellular machinery, carbohydrate and nitrogen metabolism, and stress responses was only slightly modulated: a short time lag in mixed compared to pure cultures was observed. Interestingly, the induction of several virulence factors and regulators, including the agr locus, sarA, and some enterotoxins, was strongly affected. This work clearly underlines the complexity of L. lactis antagonistic potential for S. aureus and yields promising leads for investigations into nonantibiotic biocontrol of this major pathogen.

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Leaching of Pyrite by Acidophilic Heterotrophic Iron-Oxidizing Bacteria in Pure and Mixed Cultures

Applied and Environmental Microbiology ◽

10.1128/aem.65.2.585-590.1999 ◽

1999 ◽

Vol 65 (2) ◽

pp. 585-590 ◽

Cited By ~ 72

Author(s):

Paula Bacelar-Nicolau ◽

D. Barrie Johnson

Keyword(s):

Yeast Extract ◽

Thiobacillus Ferrooxidans ◽

Pyrite Oxidation ◽

Mixed Cultures ◽

Mineral Dissolution ◽

Acidophilic Bacteria ◽

Pure Cultures ◽

Sulfur Oxidizing ◽

Thiobacillus Acidophilus ◽

Basal Salts

ABSTRACT Seven strains of heterotrophic iron-oxidizing acidophilic bacteria were examined to determine their abilities to promote oxidative dissolution of pyrite (FeS2) when they were grown in pure cultures and in mixed cultures with sulfur-oxidizingThiobacillus spp. Only one of the isolates (strain T-24) oxidized pyrite when it was grown in pyrite-basal salts medium. However, when pyrite-containing cultures were supplemented with 0.02% (wt/vol) yeast extract, most of the isolates oxidized pyrite, and one (strain T-24) promoted rates of mineral dissolution similar to the rates observed with the iron-oxidizing autotroph Thiobacillus ferrooxidans. Pyrite oxidation by another isolate (strain T-21) occurred in cultures containing between 0.005 and 0.05% (wt/vol) yeast extract but was completely inhibited in cultures containing 0.5% yeast extract. Ferrous iron was also needed for mineral dissolution by the iron-oxidizing heterotrophs, indicating that these organisms oxidize pyrite via the “indirect” mechanism. Mixed cultures of three isolates (strains T-21, T-23, and T-24) and the sulfur-oxidizing autotroph Thiobacillus thiooxidans promoted pyrite dissolution; since neither strains T-21 and T-23 nor T. thiooxidans could oxidize this mineral in yeast extract-free media, this was a novel example of bacterial synergism. Mixed cultures of strains T-21 and T-23 and the sulfur-oxidizing mixotrophThiobacillus acidophilus also oxidized pyrite but to a lesser extent than did mixed cultures containing T. thiooxidans. Pyrite leaching by strain T-23 grown in an organic compound-rich medium and incubated either shaken or unshaken was also assessed. The potential environmental significance of iron-oxidizing heterotrophs in accelerating pyrite oxidation is discussed.

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