Antimicrobial Bioactivity Research Articles

Bioactivity of endophytic Trichoderma fungal species from the plant family Cupressaceae

Trichoderma fungal species are universal soil residents that are also isolated from decaying wood, vegetables, infected mushroom and immunocompromised patients. Trichoderma species usually biosynthesize a plethora of secondary metabolites. In an attempt to explore endophytic fungi from healthy foliar tissues of the plant family Cuppressaceae, we explored Cupressus arizonica, C. sempervirens var. cereiformis, C. sempervirens var. fastigiata, C. sempervirens var. horizontalis, Juniperus excelsa, Juniperus sp. and Thuja orientalis plants and recovered several endophytic Trichoderma fungal strains from Trichoderma atroviride and Trichoderma koningii species. We found that the host plant species and biogeographical location of sampling affected the biodiversity and bioactivity of endophytic Trichoderma species. Furthermore, the bioactivity of Trichoderma isolates and the methanol extracts of their intra- and extra-cellular metabolites were assessed against a panel of pathogenic fungi and bacteria. Fungal growth inhibition, conidial cytotoxicity, minimum inhibitory concentration and minimum bactericidal concentration were evaluated and analyzed by statistical methods. Our data showed that both intra- and extracellular secondary metabolites from all endophytic isolates had significant cytotoxic and antifungal effects against the model target fungus Pyricularia oryzae and the cypress fungal phytopathogens Diplodia seriata, Phaeobotryon cupressi and Spencermartinsia viticola. Further research indicated their significant antimicrobial bioactivity against the model phytopathogenic bacteria Pseudomonas syringae, Erwinia amylovora and Bacillus sp., as well. Altogether, the above findings show for the first time the presence of T. atroviride and T. koningii as endophytic fungi in Cupressaceae plants and more importantly, the Trichoderma isolates demonstrate significant bioactivity that could be used in future for agrochemical/drug discovery and pathogen biocontrol.

Antimicrobial activity and cytocompatibility of Ag plasma-modified hierarchical TiO2 film on titanium surface

To improve the antimicrobial ability and cytocompatibility of biomedical titanium implants, many efforts have been made to modify their surface topography and chemical composition. In this work, Ag plasma-modified hierarchical TiO2 film was fabricated on titanium surface via acid etching to produce micropit, hydrothermal treatment to generate TiO2 nanorod and subsequent plasma immersion ion implantation process to impregnate Ag into TiO2 surface. In view of the potential clinical applications, their antimicrobial activity, bioactivity and cytocompatibility were systematically evaluated. The hierarchical TiO2 film showed enhanced bioactivity and bacteriostatic effect on both microbes due to more negative zeta potential, constructing the first defense line against microbial adhesion by electrostatic repulsion. Addition of embedded Ag remarkably enhanced the antimicrobial efficiency toward both microbes based on Schottky contact without Ag+ release, establishing the second defense line targeting microbial membrane. Furthermore, the addition of Ag degraded the bioactivity very little and exerted nearly no adverse or even promoted effect on MG63 cell functions, including adhesion, spreading and proliferation. This work illustrates a two-defense-line antimicrobial activity in darkness with both prior electrostatic repulsion to inhibit most microbes adhesion and posterior biocidal action to kill residual ones that luckily infiltrated through the first defense line, and provide proof of concept using both clinically relevant human pathogens. In conclusion, the Ag-embedded hierarchical TiO2 film with excellent antimicrobial activity, bioactivity and cytocompatibility provides a promising candidate for orthopedic and dental implants.

Antibacterial activity and phytochemical profile of fermented Camellia sinensis (fuzhuan tea)

Fuzhuan tea is a traditional preparation of Camellia sinensis L. (Theaceae) from Hunan, China, that is fermented with the fungus Eurotium cristatum. Metabolomic analysis was performed on fuzhuan tea extracts and compared to extracts of non-fermented green teas using ultra-performance liquid chromatography/time of flight-mass spectrometry (UPLC-ToF-MS). Principal component analysis revealed a unique phytochemical profile between the two types of tea with the largest separation visible along the third principle component, which accounted for 12.4% of dataset variation. Spectral comparison of significantly different tea metabolite features allowed tentative identification of flavonoids including catechins, fatty acid amides, and other lipids and polysaccharides. Fuzhuan tea extracts, at a concentration of 5mg/mL or less, reduced the growth of enteric pathogens Shigella sonnei and Staphylococcus aureus by 50%, and had a minimum inhibitory concentration (MIC) of 0.625mg/mL against S. aureus. These results support a distinct phytochemical profile associated with fermented fuzhuan tea compared to non-fermented green teas that warrant further investigation for novel compounds with antimicrobial bioactivity.

Culturable actinomycetes from desert ecosystem in northeast of Qinghai-Tibet Plateau

In this study, 53 actinomycetes strains were isolated from desert ecosystems located in northeast of Qinghai-Tibet Plateau and grouped into four RFLP patterns. Twenty-six actinomycetes with obvious morphology differences were chosen for phylogenetic diversity study and antimicrobial testing. As a result, the 16S rRNA gene sequencing showed that these strains belonged to Streptomyces, Micromonospora, Saccharothrix, Streptosporangium and Cellulomonas, and that most of the strains had antimicrobial bioactivity. The PKS and NRPS genes detection indicated diversified potential bioactive products of actinomycetes in this ecosystem. Among these strains, Sd-31 was chosen to study the bioactive products using HPLC-MS because of its optimum antimicrobial bioactivity. The result showed that it might produce Granatomycin A, Granatomycin C, and an unknown compound.

Sterically Stabilized Phospholipid Micelles Reduce Activity of a Candidate Antimicrobial Wound Healing Adjunct

KSLW is an antimicrobial decapeptide, presumed to associate with micelles. Linear polymeric chains of hydrophobic phospholipids tend to form micelles, spontaneously, and function as efficient drug-stabilizing delivery systems. Our goal was to examine whether association of a cationic decapeptide with sterically stabilized nanomicelles (SSMs), improves stability and antimicrobial effect in vivo, using an impaired healing model. KSLW solutions were prepared in either saline or 12 mM SSM. Bilateral circular excisional wounds were created on the backs of SKH-1 mice followed by intradermal delivery of peptide solutions. Bacterial assays were conducted to assess bioactivity of KSLW in different formulations. Fluorescence analyses demonstrated an optimum lipid:peptide ratio for loading KSLW in PEGylated phospholipid micelles to be 15:1. Stressed animals treated with KSLW–SSM preparations demonstrated no differences in microbial load at post-operative time points. In vitro assays against Staphylococcus epidermidis confirmed diminished activity of KSLW in SSM solution. The loss of KSLW antimicrobial activity may be based on electrostatic interactions with the anionic surface of SSM, which interfere with the peptide’s interaction with bacterial membranes. This study emphasizes the importance of antimicrobial peptide charge, size, and bioactivity, when designing delivery systems for wound healing agents.

Identi fication and Bioactivity of an Antitumor Actinomycete

To exploit actinomycetes from desert ecosystem of Qinghai-Tibet plateau,an antimicrobial and antitumor actinomycete Sd-31 was selectively isolated for the first time from the soil sample of the desert island in the Qinghai Lake,the northeast of Qinghai-Tibet plateau.According to physio-biochemical,chemotaxonomy and 16S rRNA gene sequence analysis,the strain was identified and named Streptomyces lateritius Sd-31.The antimicrobial bioactivity of the strain was tested by double layer agar method,and the result showed that the strain could inhibit the growth of Staphyloccocus aureus and Bacillus subtilis.According to Hoechst fluorescence microscope observation and cytotoxic test by MTT,the broth of the strain showed obvious bioactivity of leading to the apotosis of tumor cell.The stability of the broth bioactivity was tested by paper disk method,and the result showed that the antimicrobial bioactivity was stable between 20 ℃ and 80 ℃ and decreased at 100 ℃.The antimicrobial bioactivity was stable at acid and neutral treatment and decreasing with the increasing of pH at alkaline treatment.These findings provided data for exploring antitumor drugs.

Antimicrobial Bioactive Compound Isolated from the Fungus Myrothecium verrucaria

Bioactive chemical compound M1 [3-(5,5-dimethylhexyloxy) 2,2,4,4-tetramethyl-cyclohexanone] was extracted, purified and identified from the fungal culture of Myrothecium verrucaria isolated from soil in southern Iraq. The identification of the compound by using GC-Mass and H1NMR was confirmed. Solubility, toxicity, purity and the chemical formula and molecular weight of M1 compound were determined. The antimicrobial bioactivity of the purified compound against the bacterial strains E. coli and S. aureus and the dermatophytic fungus Microsporum gypseum was tested using a disc diffusion agar method. The minimal inhibitory concentration (MIC) was also performed. Purified M1 compound exhibited a good bioactivity against the tested bacteria as well as against the dermatophyte isolate.

Antagonistic bioactivity of endophytic strains isolated from Salvia miltiorrhiza

The antibiotic-producing potential of endophytic populations from medical plant of Salvia miltiorrhiza was examined. A total of 63 isolates was screened against five fungal and three bacterial species for the production of antimicrobial compounds. It showed that more isolates was antagonistic to fungi than to bacteria. One bacterial isolate named DX30 showed broad-spectrum of antagonistic activity against all the target organisms in plate assays. Morphology, physiological, chemical characteristics and 16S rRNA gene sequence analysis of strain DX30 demonstrated that it belonged to the genus Bacillus . The strain DX30 had maximum activity at temperature of 25°C and pH of 6.0 respectively and remained stable activity at temperature between 30 and 100°C and pH between 6 and 12. Strain DX30 seems promising in the biological control. Key words: Endophytes, antimicrobial bioactivity, 16S rRNA gene, Salvia miltiorrhiza.

Endophytic Fungi from Dragon's Blood Specimens: Isolation, Identification, Phylogenetic Diversity and Bioactivity

Endophytic fungi from Dragon's blood specimens of different locations of China were characterized taxonomically and investigated concerning their antimicrobial and antitumor activity against six pathogenic microbes and five tumor cells. A total of 49 endophytic fungi were obtained from Dragon's blood materials of Dracaena spp., 18 taxa were represented by 43 (87.8%) isolates and only six (12.2%) isolates were unknown. Twenty (40.8%) of the isolates displayed antimicrobial activity against at least one pathogenic microorganism. Three isolates YNDC07, BJDC06 and BJDC09 displayed significant antimicrobial activities against Staphylococcus aureus, Cryptococcus neoformans and Aspergillus fumigates, respectively. The results of antitumor activity by the MTT assay revealed that 26.5%, 69.4%, 48.9%, 6.1% and 42.9% of isolate fermentation broths displayed growth inhibition on HepG2 cells, SKVO3 cells, MCF7 cells, HL-60 cells and 293-T cells, respectively. HNDC09 and HNDC10 showed very strong antitumor activity against MCF7 and 293-T, respectively. The results showed that endophytic fungi in Dragon's blood samples were valuable in screening antitumor and antimicrobial bioactivity agents.

Characterization of a Synechocystis sp. from Egypt with the potential of bioactive compounds production

A polyphasic approach was employed to describe a unicellular coccoid cyanobacterium isolated from Terraat El Khashab, Helwan, Egypt. The cells were characterised by their small diameter (1.9–2.2 μm) and lack of buoyancy. The cultures grew best at a temperature range of 20–40°C and moderate light intensity (20–50 μmol photon m−2 s−1). To verify its cyanobacterial nature, sequencing of 16S rRNA gene using cyanobacterial specific primers was performed followed by a phylogenetic analysis. The sequence best-matched Synechocystis sp. PCC6803 with 90% similarity. The phylogenetic analysis placed the isolate within a major clade containing different Synechocystis isolates. The fatty acid composition was rich in saturated fatty acids while polyunsaturated fatty acids were scarce. The phytochemical screening revealed the presence of flavenoids, alkaloids and saponins and absence of tannins. Vitamin C was also present in a considerable quantity. Some of the lipophilic fractions showed antimicrobial bioactivity against several pathogens. The pure bioactive compound from highest bioactive fraction was identified as oleic acid amide (M.wt.281) using chemical analyses including FT/IR, UV, proton H-NMR and GC-mass. The study highlights the importance of investigating the biotechnological potential of microorganisms inhabiting unusual niches.

ANTIFUNGAL PROPERTIES OF SOME MEDICINAL PLANTS AGAINST UNDESIRABLE AND MYCOTOXIN-PRODUCING FUNGI

Antifungal effects of essential oils obtained from five aromatic plants (lemon grass, brasil, sage, clove and rosemary) purchased from a local market in Egypt, were extracted to obtain the oil fraction and screened in vitro against three different pathogenic fungi, Aspergillus flavus (A. flavus), Asprgillus parasiticus (A.parasiticus) and Asprgillus ochraceus (A. ochraceus). The oil fraction from each tested plant, was carried out using water extraction and used to determine its inhibitory effects on both the fungal isolates. Also, the MIC of each oil extract and its content of the phytochemicals of phlenoles, flavonoides and terpenoids were determined. Data exhibited wide range of the inhibitory action occurred against the tested microorganisms where, bioactivity of the five plants reached its maximum using clove and its minimum using sage extracts against the tasted microorganisms. No bioactivity was observed in the treatment(s) of sage extract against the mold Asp. ochraceus. The other three extracts of rosemary, brasil and lemon grass showed roughly the same bioactivity. Also, data obtained from MIC and semi-quantitative determinations confirmed the results obtained from the antimicrobial bioactivity study. Except sage extract, the MIC of the other four extracts were ranged between 0.35-1.5 mg/ml, reached its maximum using clove and its minimum using lemon grss extracts. As well, the semi-quantitative determination of the phytochemicals of phenols, flavonides and terpenoids proved that clove extract had the highest concentration of terpenoids, while sage extract showed traces from the three phytochemicals. The other three extracts of basil, rosmary and lemon grass showed roughly the same content of the sum of the three phytochemicals. These effects against the tested microorganisms indicated the possible ability of each essential oil as a food preservative.Therefore, it is suggested that further work be performed on food to test the antifungal and antibacterial properties of these oil fractions.

Influence of an antimicrobial treatment on the strength properties of polyamide/elastane weft‐knitted fabric

AbstractPolyamide/elastane weft‐knitted fabric, as a suitable compression material, was treated with gentamicin sulfate and a natural antimicrobial preparation of the autochthonous essential oil of Picea abies. The antimicrobial bioactivity of the treated fabric in vitro was tested for different groups of bacteria and a fungus (Staphylococcus aureus, Escherichia coli, Klabsiella, and Candida albicans). The results of the experiment showed that the antimicrobial‐treated knitted fabric expressed a wide range of bactericidal, fungicidal, and bacteriostatic activity versus the various groups of microorganisms. The influence of the antimicrobial treatments on the tensile strength and elongation, tear strength and elongation, stiffness, and elasticity of the chosen test material was also examined. These properties of the fabric were changed after the antimicrobial treatments. Both the tensile strength and tear strength increased about 14% after the treatment. The scope of the experiment also included the testing of the compression distribution at the skin/knitted fabric interface on the legs of human test subjects. Pressure generated by the application of the knitted fabric on the leg surface increased in correlation with a decrease in the leg circumference. On the basis of these observations, it was concluded that the knitted fabric could be used as a compression textile before and after the treatment. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4012–4019, 2007

Elution of metronidazole and gentamicin from polymethylmethacrylate beads.

To characterize the elution and bioactivity of metronidazole and gentamicin sulfate polymerized, individually and in combination, with polymethylmethacrylate (PMMA). In vitro experimental study. PMMA beads containing metronidazole (3 concentrations), gentamicin sulfate, or metronidazole and gentamicin sulfate were immersed in 5 mL of phosphate-buffered saline in triplicate. Eluent was replaced at specified time intervals for 1 or 21 days, and antibiotic concentrations were measured by high-performance liquid chromatography. Changes in antibiotic bioactivity attributable to polymerization or copolymerization of the antibiotics with PMMA, ethylene oxide sterilization, and storage of AIPMMA beads containing metronidazole were evaluated. Antibiotic elution patterns were similar for all groups. Day 1 elution for groups containing metronidazole or gentamicin individually represented a mean 63%-66% and 79%, respectively, of the 21-day total. Approximately 50% of the day 1 elution occurred during the first hour. The elution of metronidazole was dose dependent. The elution of metronidazole (day 3-21) and gentamicin (all days) was significantly greater when metronidazole and gentamicin were combined (P <.05). The addition of metronidazole delayed polymerization of PMMA. Neither polymerization nor copolymerization of metronidazole and gentamicin with PMMA, gas sterilization, or 2-month storage of beads containing metronidazole significantly affected antimicrobial bioactivity. Metronidazole elution from PMMA was dose dependent. Copolymerization of metronidazole and gentamicin sulfate in PMMA resulted in increased rates of elution. Intraoperative preparation of metronidazole-impregnated PMMA beads is not practical, but sterilization and storage for 2 months should not affect efficacy. The local delivery of biologically active metronidazole and gentamicin by elution from PMMA is feasible.

Prolonged Stability of Antimicrobial Activity in Peritoneal Dialysis Solutions

To evaluate the stability of the antimicrobial chemical and bioactivity of gentamicin, vancomycin, and gentamicin and vancomycin in combination, and the stability of the bioactivity of ceftazidime, admixed in standard peritoneal dialysis solutions and then maintained over a 14-day period at room temperature or under refrigeration. Peritoneal dialysis center and microbiology laboratory at a military, teaching medical center. Standard peritoneal dialysate bags admixed with gentamicin, vancomycin, gentamicin and vancomycin in combination, or ceftazidime were stored at either 4 degrees C or 20 degrees C for 14 days. Sequential aliquots were withdrawn and assayed for antibiotic activity by bioassay and, except for ceftazidime, immunoassay for chemical activity. The bioassay was performed using a standardized Kirby-Bauer disc method. Significance was determined by ANOVA and, where the effect size was significant at the p < 0.05 level, the application of the paired t-test or the Wilcoxon signed rank test to the difference in activity between the first and last samples. Antibiotic concentration by immunoassay did not significantly deteriorate over 14 days for vancomycin or gentamicin when either room temperature or refrigerated samples were studied. By bioassay, gentamicin and ceftazidime, but not vancomycin, lost moderate but significant activity over 14 days when refrigerated bags were assayed (except for an insignificant decrement in gentamicin in the combined vancomycin and gentamicin bags). Bags stored at room temperature, in general, lost significant bioactivity over 14 days, but to levels where clinical efficacy would still be expected. The vancomycin bioassay performed on the combination bags demonstrated a remarkably enhanced bioactivity, presumably reflecting synergy with gentamicin. These data indicate that the study antibiotics admixed with peritoneal dialysis fluids retain stable chemical activity, whether refrigerated or kept at room temperature, for at least 14 days. A moderate decrement in bioactivity occurred for study antibiotics when stored either refrigerated or at room temperature over 14 days, although clinically significant levels were maintained. The clinical significance of a possible synergy between vancomycin and gentamicin is yet to be determined.