Inhibitory relationships of resident bacteria isolated from the mantle fluids of Crassostrea virginica.

Thirteen aerobic, halotolerant marine bacterial strains were isolated from the mantle fluids and associated mucus of the eastern oyster Crassostrea virginica harvested from the highly impacted Black Rock Harbor in western Long Island Sound. All isolated strains were Gram negative and had previously been identified using 16S RNA gene sequence analysis. These 13 strains were examined for their ability to inhibit the growth of each other employing a diffusion agar method used by antibiotic assays. All challenger strains were able to inhibit at least one of the indicator isolates. Enhanced antimicrobial activity was observed from cultures of Pseudoalteromonas sp. (L), Shewanella sp. (H), Thalassospira sp. (JA), and Alteromonas sp. (JB) when used to challenge the indicator isolates. The indicator isolate most sensitive to antimicrobial activity was another Pseudoalteromonas species (KC) whose growth was inhibited by 10 of the challenger strains, whereas Pseudoalteromonas (L) was resistant to all growth challenges. Growth autoinhibition was observed with isolates Tenacibaculum ascidiaceicola (KC), Vibrio (B), and Shewanella (H) during a 24 h incubation. No antimicrobial growth inhibition was detected when 24 and 48 h cell-free extracts of these isolates were used to challenge indicator isolate growth.

Disinfection mechanism of the photocatalytic activity of SnO2 thin films against Candida albicans, proposed from experimental and simulated perspectives.

Nosocomial infections are an important health problem and cause of complications and death in hospitalized patients. This problem should be solved from the preventive angle, avoiding the spread of infections by designing disinfection methods based on the photocatalytic activity of semiconductor materials such as tin oxide (SnO2). The antimicrobial activity of UV light was tested by using inoculation with Candida albicans ATCC10231 on SnO2 thin films and counting colony forming units (CFU). The interaction of UV light with SnO2 was analyzed by density functional theory (DFT) and the extension to the Hubbard model (DFT+U) schemes to predict the electron behavior at the subatomic level. After exposure to UV light, C. albicans showed a reduction of 36.5% in viable cells, and when SnO2 was included, cell viability was reduced by 60.2%. Measurements of the electronic structure obtained by the first-principle calculations under the DFT and DFT+U schemes showed that the O-p orbitals mediate the oxidation process in the bulk semiconductor. By including the surface effects when cleaving the (1 0 0) plane, the three orbitals O-p, Sn-p, and Sn-s are the mediators. SnO2 films are promising antimicrobial coatings because UV light has a synergic activity with thin films, resulting in faster disinfection.

[Anti-microbial activity of Rosmarinus officinalis and Zingiber officinale extracts on the species of the genus Candida and on Streptococcus pneumonia]. / Activité antimicrobienne des extraits de Rosmarinus officinalis et Zingiber officinale sur les espèces du genre Candida et sur Streptococcus pneumoniae.

OBJECTIVE: Identifying plant extracts that could be used as new treatments for candidiasis and Streptococcus pneumoniae infections. METHODS: In this work, we tested the activity of the ethanolic and methanolic extracts of Rosmarinus officinalis and Zingiber officinale on Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei and Streptococcus pneumoniae. The anti-microbial activity was first tested in vitro, then in vivo on mice and rats. RESULTS: The results showed that the methanolic extract of Rosmarinus officinalis and the ethanolic extract of Zingiber officinale were the most active on all the tested micro-organisms. The most sensitive species were Candida albicans, Candida krusei and Streptococcus pneumoniae. The in vivo anti-microbial activity reported that the ethanolic extract of Zingiber officinale was the most active on the three species. On the contrary, Candida glabrata and Candida tropicalis were more sensitive to the methanolic extract of Rosmarinus officinalis, but these species were considered as the most resistant yeasts. CONCLUSION: The ethanolic extract of Zingiber officinale was more active than fluconazole and amoxicillin on Candida albicans, Candida krusei and Streptococcus pneumoniae, so, it could be considered for treating infections by these species. Similarly, the methanolic extract of Rosmarinus officinalis could be effective for treating candidiasis by Candida glabrata and Candida tropicalis.

Mode of action of nisin on Escherichia coli.

Nisin is a class I polycyclic bacteriocin produced by the bacterium Lactococcus lactis, which is used extensively as a food additive to inhibit the growth of foodborne Gram-positive bacteria. Nisin also inhibits growth of Gram-negative bacteria when combined with membrane-disrupting chelators such as citric acid. To gain insight into nisin's mode of action, we analyzed chemical-genetic interactions and identified nisin-sensitive Escherichia coli strains in the Keio library of knockout mutants. The most sensitive mutants fell into two main groups. The first group accords with the previously proposed mode of action based on studies with Gram-positive bacteria, whereby nisin interacts with factors involved in cell wall, membrane, envelope biogenesis. We identified an additional, novel mode of action for nisin based on the second group of sensitive mutants that involves cell cycle and DNA replication, recombination, and repair. Further analyses supported these two distinct modes of action.

Advances in lactoferrin research concerning bovine mastitis.

Lactoferrin is a multifunctional, iron-binding glycoprotein found in milk and other exocrine secretions. Lactoferrin in milk plays vital roles in the healthy development of newborn mammals, and is also an innate resistance factor involved in the prevention of mammary gland infection by microorganisms. Inflammation of the udder because of bacterial infection is referred to as mastitis. There have been many investigations into the relationships between lactoferrin and mastitis, which fall into several categories. The main categories are fluctuations in the lactoferrin concentration of milk, lactoferrin activity against mastitis pathogens, elucidation of the processes underlying the onset of mastitis, participation of lactoferrin in the immune system, and utilization of lactoferrin in mastitis treatment and prevention. This minireview describes lactoferrin research concerning bovine mastitis. In the 1970s, many researchers reported that the lactoferrin concentration fluctuates in milk from cows with mastitis. From the late 1980s, many studies clarified the infection-defense mechanism in the udder and the contribution of lactoferrin to the immune system. After the year 2000, the processes underlying the onset of mastitis were elucidated in vivo and in vitro, and lactoferrin was applied for the treatment and prevention of mastitis.

Probiotic Lactobacillus casei expressing porcine antimicrobial peptide PR39 elevates antibacterial activity in the gastrointestinal tract.

PR39, a 4.7 kDa proline-rich antimicrobial peptide, acts as a cationic host defense peptide. In addition to killing bacteria, PR39 mediates inflammatory reactions, including cell proliferation, migration, wound healing, and angiogenesis. Here, we examined the antibacterial effects of this peptide. The synthetic gene fragment PR39 was inserted into the secretory expression vector plasmid pPG:612 of Lactobacillus casei, yielding the recombinant strain pPG:612-PR39/L. casei 393. In vitro antibacterial tests showed that expression of the PR39 peptide in recombinant L. casei resulted in antibacterial activity against Escherichia coli and Salmonella but had only minor antibacterial effects in Staphylococcus aureus. In addition, BALB/c mice fed the recombinant pPG:612-PR39/L. casei 393 grew better and had increased peripheral blood lymphocyte percentages, white blood cell numbers, and spleen indices than mice in the control group. Scanning electron microscopy showed that jejunum and duodenum villus height, crypt depth, and the ratio of villus height/crypt depth in the intestinal villi also increased. Moreover, mice fed the recombinant strain showed significantly lower mortality rates than the control group mice when challenged with the enterotoxigenic E. coli K88+. Thus, this recombinant expression system had the beneficial characteristics of both L. casei and PR39, supporting its potential as an animal feed additive.

Synthesis, characterization and biological studies of substituted quinozoline-4-(3H)-ones containing diazepine moiety.

The synthesis and characterization of new series of 1,4-benzodiazepine derivatives have been presented. The structures were confirmed by elemental analyses, IR spectral, (1)H NMR spectral and mass spectral data. All the compounds were screened for in vitro antimicrobial and anthelmintic activities. The antibacterial activity was tested against Staphylococcus aureus (Gram positive), Bacillus cereus (Gram positive), Escherichia coli (Gram negative) and Pseudomonas aeruginosa (Gram negative). The antifungal activity was tested against Aspergillus niger and Candida albicans. All the compounds showed considerable antimicrobial activity against the microorganism studied. The significant anthelmintic activity of all novel compounds was demonstrated against Pheretima posthuma. Based on the nature of substituent present, the structure-activity correlation of novel compounds was discussed.

Antifungal and antibacterial activity of marine microorganisms.

In order to explore marine microorganisms with pharmaceutical potential, marine bacteria, collected from different coastal areas of the Moroccan Atlantic Ocean, were previously isolated from seawater, sediment, marine invertebrates and seaweeds. The antimicrobial activities of these microorganisms were investigated against the pathogens involved in human pathologies. Whole cultures of 34 marine microorganisms were screened for antimicrobial activities using the method of agar diffusion against three Gram-positive bacteria, two Gram-negative bacteria, and against yeast. The results showed that among the 34 isolates studied, 28 (82%) strains have antimicrobial activity against at least one pathogen studied, 11 (32%) strains have antifungal activity and 24 (76%) strains are active against Gram-positive bacteria, while 21 (62%) strains are active against Gram-negative bacteria. Among isolates having antimicrobial activity, 14 were identified and were assigned to the genera Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Enterococcus, Pantoea and Pseudomonas. Due to a competitive role for space and nutrient, the marine microorganisms can produce antibiotic substance; therefore, these marine microorganisms were expected to be potential resources of natural antibiotic products.

[Evaluation of different procedures for the extraction of phenolic compounds from a medicinal plant: Verbena officinalis]. / Évaluation de différents procédés d'extraction des composés phénoliques d'une plante médicinale : Verbena officinalis.

Since ancient times, plants have been the main source of bioactive molecules, such as phenolic compounds, capable of remedying various diseases. However, polyphenols' content and efficiency vary greatly as a function of several intrinsic and extrinsic factors. To optimize the procedure for the extraction of active molecules from the medicinal plant Verbena officinalis, effects of the plant origin, selected solvent, and extraction method were assessed. V. officinalis aerial parts were collected in two different regions of Tunisia (Bizerte and Ain Draham), and their bioactive molecules were extracted by maceration, decoction, and by the Soxhlet apparatus, either with water or with ethanol. Significant variability in the extracts' contents of phenolic compounds as well as their antioxidant and antimicrobial capacities were noted depending on the different studied factors. In particular, ethanol extracts were found to generally contain higher concentrations of phenolic compounds and more potent antioxidant capacities than water extracts. However, when tested against various pathogenic bacteria, water extracts were most often at least as active as ethanol extracts to inhibit bacteria growth in vitro. Finally, differences were also observed between V. officinalis samples from Bizerte compared to Ain Draham area. All of these results emphasize the need of adapting various parameters for the optimal extraction of bioactive molecules from a medicinal plant such as V. officinalis.

Title: Évaluation de différents procédés d'extraction des composés phénoliques d'une plante médicinale : Verbena officinalis. Abstract: Depuis la nuit des temps, les plantes ont été la source principale de molécules bioactives, tels les composés phénoliques, capables de remédier à diverses maladies. Cependant, le contenu et l'activité des polyphénols dépendent d'un certain nombre de facteurs intrinsèques et extrinsèques. Dans le but d'optimiser les procédés d'obtention des principes actifs de la verveine (Verbena officinalis), les effets de la provenance de la plante, du solvant et de la méthode d'extraction ont été évalués. Ainsi, la partie aérienne de V. officinalis a été collectée dans deux régions différentes de la Tunisie (Bizerte et Ain Draham). L'extraction a été réalisée par macération, décoction et par l'appareil de Soxhlet tantôt avec de l'eau tantôt avec de l'éthanol pur. Une variabilité significative des teneurs en composés phénoliques ainsi que des capacités antioxydantes et antimicrobiennes des extraits a été observée en fonction des facteurs étudiés. De manière générale, les extraits éthanoliques sont plus riches en composés phénoliques et présentent des activités antioxydantes plus fortes que les extraits aqueux. Cependant, vis-à-vis de différentes souches pathogènes, les extraits aqueux sont souvent au moins aussi puissants que les extraits éthanoliques pour inhiber la croissance bactérienne in vitro. De plus des différences notables sont observées selon que V. officinalis provient de la région de Bizerte ou d'Ain Draham. Ces résultats montrent que la prise en compte de plusieurs paramètres est nécessaire pour optimiser l'efficacité des procédures d'extraction des molécules bioactives de V. officinalis.

Preparations based on minerals extracts of Calicotome villosa roots and bovine butyrate matter: Evaluation in vitro of their antibacterial and antifungal activities.

OBJECTIVE: The use of preparations based on minerals extracts of Calicotome villosa and butter is born from the misuse of drugs without specific microbiological analyzes. Seventeen different preparations were performed. The antibacterial and antifungal activities were determined on five bacteria and two fungi strains respectively. MATERIAL AND METHODS: C.villosa ashes are obtained by incineration of roots plant at 498°C for 4hours. They are analyzed to determine the shape of the particles and the mineral constituents by scanning electronic microscopy (SEM) and energy dispersive X-ray spectrometry (EDX) techniques respectively. The effectiveness of preparations or tablets is measured in solid medium. It allows to calculating the diameter of the inhibition zone for the antibacterial activity as well as the diameter of mycelia growth and the critical values (MIC, MFC, IC50 and IC90) for the antifungal activity. Finally, the results are compared to the activity of a commercial positive control aiming to give value of the observed activity. RESULTS: SEM observations reveal the presence of nanoparticles agglomerated with size of about 50nm. The EDX analyzes indicate the presence of Fe, Na, Al, Mg, Si, K, Ca, O2 and C. Among all the results, the preparation (Bs+A) or (Bsd+A) can completely inhibit the growth of two fungal pathogens. The activity of the preparation is faced with the activity of the synthetic fungicide nystatin. CONCLUSION: The efficacy of the preparation (Bs+A) or (Bsd+A) is larger than that of nystatin against Aspergillus sp. and Fusarium sp. The preparation could serve as natural antifungal for the pharmaceutical industry.

Preparations based on minerals extracts of Calicotome villosa roots and bovine butyrate matter: Evaluation in vitro of their antifungal activity.

OBJECTIVE: The use of preparations based on minerals extracts of Calicotome villosa and butter is born from the misuse of drugs without specific microbiological analyzes. Seventeen different preparations were performed. The antibacterial and antifungal activities were determined on five bacteria and two fungi strains respectively. MATERIAL AND METHODS: C. villosa ashes are obtained by incineration of roots plant at 498°C for 4hours. They are analyzed to determine the shape of the particles and the mineral constituents by scanning electronic microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques respectively. The effectiveness of preparations or tablets is measured in solid medium. It allows to measure the diameter of the inhibition zone for the antibacterial activity as well as the diameter of mycelia growth and the critical values (MIC, MFC, IC50 and IC90) for the antifungal activity. Finally, the results are compared to the activity of a commercial positive control aiming to give value of the observed activity. RESULTS: SEM observations reveal the presence of nanoparticles agglomerated with size of about 50nm. The EDX analyzes indicate the presence of Fe, Na, Al, Mg, Si, K, Ca, O2 and C. Among all the results, the preparation (Bs+A) or (Bsd+A) can completely inhibit the growth of two fungal pathogens. The activity of the preparation is faced with the activity of the synthetic fungicide nystatin. CONCLUSION: The efficacy of the preparation (Bs+A) or (Bsd+A) is higher than that of nystatin against Aspergillus sp. and Fusarium sp. The preparation could serve as natural antifungal for the pharmaceutical industry.

Antifungal activity of a Saharan strain of Actinomadura sp. ACD1 against toxigenic fungi and other pathogenic microorganisms.

A new strain of actinobacteria, designated ACD1, was isolated from a Saharan soil sample in the Hoggar region (Algeria). Morphological study led to this strain being classified as a member of the Actinomadura genus. Phylogenetic analysis based on the 16S rRNA gene showed that the strain is closely related to Actinomadura sediminis DSM 45500(T) (98.5% sequence similarity). Furthermore, strain ACD1 presented a strong activity against mycotoxigenic and phytopathogenic fungi, including Aspergillus and Fusarium strains, and other pathogenic microorganisms. The kinetics of antimicrobial activity were investigated on ISP-2, Bennett and TSB media. Four solvents (n-hexane, dichloromethane, ethyl acetate and n-butanol) were used for the extraction of the produced antibiotic. The highest antimicrobial activity was obtained using the butanolic extract from the ISP-2 medium after seven days of fermentation culture. The active antibiotic was purified by reverse-phase HPLC using a C18 column. The UV-visible and mass spectra were determined. The minimum inhibitory concentrations (MIC) of this antibiotic were determined against pathogenic microorganisms.

A non-polyenic antifungal produced by a Streptomyces yatensis strain isolated from Mellah Lake in El Kala, North-East of Algeria.

OBJECTIVE: This study aimed at describing one actinomycete strain E65 that was isolated from the water of Mellah Lake in El Kala, North-East of Algeria that produces a non-polyenic antifungal. MATERIALS AND METHODS: Actinomycetes were isolated from Mellah Lake water and screened for antimicrobial activity. Antimicrobial assays were performed on ISP2 agar. The taxonomic position of the strain E65 was determined regarding phenotypic and 16S DNA sequences features. Time course of antifungal metabolites production was evaluated against Candida albicans on ISP2, ISP1 and GYEA broth. The active antifungal compound was extracted using dichloromethane and revealed by a thin layer of chromatography, chemical reagents, UV-visible and infrared spectroscopy. RESULTS: A total of 104 actinomycetes were isolated and screened for antimicrobial activity; 21 strains were active against Staphylococcus aureus, Escherichia coli and Candida albicans. The strain E65 showed a high in vitro activity against S. aureus and C. albicans and a good antifungal activity against a clinical C. albicans strain resistant to 5-fluorocytosine. Its 16S rRNA sequence shared 99% similarity with the Streptomyces yatensis type strain within the Streptomyces violaceusniger subclade of the Streptomyces hygroscopicus clade. It produced a non-polyenic antifungal, the IR spectrum of the antifungal extract corresponded to none of the antimicrobials compounds known to be produced by actinomycete of the S. hygroscopicus clade. CONCLUSION: The wetlands of El Kala, Algeria are a potential source of bioactive actinomycete that deserves to be explored and exploited. The Streptomyces yatensis E65 strain isolated from Mellah Lake brackish water produces a remarkable antifungal compound which original non-polyenic structure warrants further characterization.

Antimicrobial activity of saquayamycins produced by Streptomyces spp. PAL114 isolated from a Saharan soil.

A new strain of actinomycete designated PAL114, producing antimicrobial compounds, was isolated from a Saharan soil in Ghardaïa, Algeria. Morphological and chemical studies showed that this strain belonged to the genus Streptomyces. Two bioactive compounds, named P41A and P41B, were extracted by dichloromethane from the cell-free supernatant broth of strain PAL114 and were purified by HPLC. Minimum inhibitory concentrations of the pure antibiotics were determined against yeasts, filamentous fungi and bacteria, most of which are pathogenic or toxigenic for human and multiresistant to antibiotics. The strongest activities were observed against Candida albicans M3 and Bacillus subtilis ATCC 6633. The chemical structures of the compounds were determined by spectroscopic analysis of UV-visible and 1H and 13C NMR spectra and spectrometric analysis of mass spectrum. The compounds P41A and P41B were identified as saquayamycins A and C, respectively. These compounds belong to the aquayamycin-group antibiotics, which are known in the literature for their anticancer and antibacterial activities.