Burdock fructooligosaccharide enhances biocontrol of Rhodotorula mucilaginosa to postharvest decay of peaches

The influence of adding burdock fructooligosaccharide (BFO) in the culture media on the efficacy of Rhodotorula mucilaginosa in controlling postharvest decay of peaches and its possible mode of action were investigated. The antagonistic activity of R. mucilaginosa to Rhizopus decay and blue mold decay of peaches was greatly enhanced through cultivation in the nutrient yeast dextrose agar (NYDA) medium amended with BFO at the concentration of 0.32%, compared with that cultivated in NYDB without BFO. R. mucilaginosa at 1 × 10⁸ cells/mL cultivation in the NYDB media did not reduce the natural decay incidence of peaches, compared with the control after 30 d at 4 °C followed by 7 d at 20 °C. However, R. mucilaginosa cultivation in the NYDB media amended with BFO at the concentration of 0.32% reduced the natural decay incidence of peaches. The population of R. mucilaginosa harvested from NYDB amended with BFO at 0.32% increased rapidly in peach wounds compared to that harvested from NYDB without BFO no matter peaches were stored at 20 °C or 4 °C. The activities of chitinase and β-1,3-glucanase of cell-free culture filtrate of R. mucilaginosa harvested from NYDB amended with BFO at 0.32% were higher than that at other concentrations and the control.     

A comparative analysis of microflora during biofilm development on grape seeds exposed to methanol in a biofilter

The attachment of microorganisms onto biotic surfaces to form biofilm structures on the support media of a biofilter has great impact on biodegradation systems. This study examined the composition of the microbial community that developed on grape seeds (GS) used as support media in methanol degradation biofilters. They were analyzed using conventional microbiology techniques and API galleries. Analysis of microbial counts showed that, in GS before methanol exposure, bacteria and filamentous fungi were predominant over yeasts. In contrast, GS exposed to methanol exhibited more bacteria and yeasts than fungi. Most of the Gram-negative bacteria were the Pseudomonas genus, Bacillus staerothermophilus, Bacillus amyloliquefaciens, and Bacillus pumilus. Rhodotorula mucilaginosa was the primary yeast found. The filamentous fungi Aspergillus sp. Cladosporium cladosporioides, Fusarium sp., and Alternaria sp. were also detected. No Gram-positive bacteria growth was found on GS exposed to methanol. Using scanning electron microscopy, biofilm formation on the GS was examined to reveal the presence of both prokaryotic and eukaryotic microorganisms as biomass accumulation was visible on the seeds. Seeds exposed to methanol for 90 days showed a mature biofilm with cuticle and epidermal layer decline, as well as biofilm dissolution into grape seed integuments.     

Microbial diversity in the anaerobic tank of a full-scale produced water treatment plant

Microbial characteristics in the anaerobic tank of a full-scale produced water treatment plant capable of anaerobic hydrocarbon removal were analyzed and compared to those in the influent produced water using cultivation-independent molecular methods. Clones related to methanogens including the methylotrophic Methanomethylovorans thermophila and hydrogen- and the formate-utilizing Methanolinea tarda were in abundance in both samples, but greater numbers of M. tarda-like clones were detected in the biofilm library. Both DGGE and cloning analysis results indicated that the archaea in the biofilm were derived from the influent produced water. Bacterial communities in the influent and biofilm samples were significantly different. Epsilonproteobacteria was the dominant bacterial group in the influent while Nitrospira and Deltaproteobacteria were the predominant groups in the biofilm. Many clones related to syntrophic bacteria were found among the Deltaproteobacteria. One Deltaproteobacteria clone was related to Syntrophus, which is commonly found in methanogenic hydrocarbon-degrading consortia. A number of Deltaproteobacteria clones were assigned to the clone cluster group TA, members of which predominate in various methanogenic consortia that degrade aromatic compounds. These results suggest that a microbial community associated with methanogenic hydrocarbon degradation may have been established in the biofilm.     

Synergistic effect of Pseudomonas putida and Bacillus amyloliquefaciens ameliorates drought stress in chickpea (Cicer arietinum L.)

Two plant growth promoting rhizobacteria (PGPR) Pseudomonas putida NBRIRA and Bacillus amyloliquefaciens NBRISN13 with ability to tolerate abiotic stress along with multiple PGP traits like ACC deaminase activity, minerals solubilisation, hormones production, biofilm formation, siderophore activity were evaluated for their synergistic effect to ameliorate drought stress in chickpea. Earlier we have reported both the strains individually for their PGP attributes and stress amelioration in host plants. The present study explains in detail the possibilities and benefits of utilizing these 2 PGPR in consortium for improving the chickpea growth under control and drought stressed condition. In vitro results clearly demonstrate that both the PGPR strains are compatible to each other and their synergistic growth enhances the PGP attributes. Greenhouse experiments were conducted to evaluate the effect of inoculation of both strains individually and consortia in drought tolerant and sensitive cultivars (BG362 and P1003). The growth parameters were observed significantly higher in consortium as compared to individual PGPR. Colonization of both PGPR in chickpea rhizosphere has been visualized by using gfp labeling. Apart from growth parameters, defense enzymes, soil enzymes and microbial diversity were significantly modulated in individually PGPR and in consortia inoculated plants. Negative effects of drought stress has been ameliorated and apparently seen by higher biomass and reversal of stress indicators in chickpea cultivars treated with PGPR individually or in consortia. Findings from the present study demonstrate that synergistic application has better potential to improve plant growth promotion under drought stress conditions.     

丛枝菌根对有机污染土壤的修复作用及机理

丛枝菌根(AM)是丛枝菌根真菌(AMF)与植物根系相互作用的互惠共生体,能改良土壤结构,增强植物抗性.自然界中已知的AMF有170多种,分布广泛,且可与大多数植物共生.利用AM修复有机污染土壤正成为一个崭新的研究方向.本文综述了AM对多环芳烃、酞酸脂、石油和农药等一些典型有机污染物污染土壤的修复作用.AM修复有机污染土壤的机理主要包括:AMF代谢有机污染物;AM分泌酶,降解污染物;AM影响根系分泌作用,并促进根际微生物对有机污染物的降解;AMF宿主植物吸收积累污染物.AM修复研究中,高效AMF的筛选、复合菌种效应、土壤老化、AM作用下植物对有机污染物的吸收积累等几方面仍有待于深入研究.     

Disruption of Putrescine Biosynthesis in Shewanella oneidensis Enhances Biofilm Cohesiveness and Performance in Cr(VI) Immobilization

Although biofilm-based bioprocesses have been increasingly used in various applications, the long-term robust and efficient biofilm performance remains one of the main bottlenecks. In this study, we demonstrated that biofilm cohesiveness and performance of Shewanella oneidensis can be enhanced through disrupting putrescine biosynthesis. Through random transposon mutagenesis library screening, one hyperadherent mutant strain, CP2-1-S1, exhibiting an enhanced capability in biofilm formation, was obtained. Comparative analysis of the performance of biofilms formed by S. oneidensis MR-1 wild type (WT) and CP2-1-S1 in removing dichromate (Cr₂O₇²⁻), i.e., Cr(VI), from the aqueous phase showed that, compared with the WT biofilms, CP2-1-S1 biofilms displayed a substantially lower rate of cell detachment upon exposure to Cr(VI), suggesting a higher cohesiveness of the mutant biofilms. In addition, the amount of Cr(III) immobilized by CP2-1-S1 biofilms was much larger, indicating an enhanced performance in Cr(VI) bioremediation. We further showed that speF, a putrescine biosynthesis gene, was disrupted in CP2-1-S1 and that the biofilm phenotypes could be restored by both genetic and chemical complementations. Our results also demonstrated an important role of putrescine in mediating matrix disassembly in S. oneidensis biofilms.     

Diatoms in Acid Mine Drainage and Their Role in the Formation of Iron-Rich Stromatolites

Adverse conditions in the acid mine drainage (AMD) system at the Green Valley mine, Indiana, limit diatom diversity to one species, Nitzschia tubicola. It is present in three distinct microbial consortia: Euglena mutabilis-dominated biofilm, diatomdominated biofilm, and diatom-exclusive biofilm. E. mutabilis dominates the most extensive biofilm, with lesser numbers of N. tubicola, other eukaryotes, and bacteria. Diatom-dominated biofilm occurs as isolated patches containing N. tubicola with minor fungal hyphae, filamentous algae, E. mutabilis, and bacteria. Diatom-exclusive biofilm is rare, composed entirely of N. tubicola.

Diatom distribution is influenced by seasonal and intraseasonal changes in water temperature and chemistry. Diatoms are absent in winter due to cool water temperatures. In summer, isolated patchy communities are present due to warmer water temperatures. In 2001, the diatom community expanded its distribution following a major rainfall that temporarily diluted the effluent, creating hospitable conditions for diatom growth. After several weeks when effluent returned to preexisting conditions, the diatom biofilm retreated to isolated patches, and E. mutabilis biofilm flourished.

Iron-rich stromatolites underlie the biofilms and consist of distinct laminae, recording spatial and temporal oscillations in physicochemical conditions and microbial activity. The stromatolites are composed of thin, wavy laminae with partially decayed E. mutabilis biofilm, representing microbial activity and iron precipitation under normal AMD conditions. Alternating with the wavy layers are thicker, porous, spongelike laminae composed of iron precipitated on and incorporated into radiating colonies of diatoms. These layers indicate episodic changes in water chemistry, allowing diatoms to temporarily dominate the system.     

Zinc oxide nanoparticle inhibits the biofilm formation of <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis>

Biofilms are structured consortia of microbial cells that grow on living and non living surfaces and surround themselves with secreted polymers. Infections with bacterial biofilms have emerged as a foremost public health concern because biofilm growing cells can be highly resistant to both antibiotics and host immune defenses. Zinc oxide nanoparticles have been reported as a potential antimicrobial agent, thus, in the current study, we have evaluated the antimicrobial as well as antibiofilm activity of zinc oxide nanoparticles against the bacterium Streptococcus pneumoniae which is a significant cause of disease. Zinc oxide nanoparticles showed strong antimicrobial activity against S. pneumoniae, with an MIC value of 40 μg/ml. Biofilm inhibition of S. pneumoniae was also evaluated by performing a series of experiments such as crystal violet assay, microscopic observation, protein count, EPS secretion etc. using sub-MIC concentrations (3, 6 and 12 µg/ml) of zinc oxide nanoparticles. The results showed that the sub-MIC doses of zinc oxide nanoparticles exhibited significant anti-biofilm activity against S. pneumoniae, with maximum biofilm attenuation found at 12 μg/ml. Taken together, the results indicate that zinc oxide nanoparticles can be considered as a potential agent for the inhibition of microbial biofilms.     

Predominance of non-Streptococcus mutans bacteria in dental biofilm and its relation to caries progression

This study aims to assess differences in biofilm bacterial composition between patients with low and high caries. Patients without a medical problem and with no history of antibiotic use, mouth wash or fluoride application in the previous 3 months were recruited. Caries was recorded at cavitation level; score was calculated by a national mean (dmft of 4.8 and DMFT of 2.7). Pooled biofilm samples were collected from mesial, distal, buccal, lingual, and occlusal surfaces. Based on caries experience, individuals were classified into low and high caries and both groups were compared regarding bacteria identified using 16S rRNA gene sequencing, and molecular phylogenetic analysis of the isolates was performed. A total of twenty seven randomly selected samples with low (n = 13) and high (n = 14) caries. Identification of oral bacteria was performed using 16S rRNA sequence, Rothia mucilaginosa and R. aeria were identified in low caries individuals, while R. dentocariosa was detected in high caries individuals. Two Streptococcus spp. were identified only in low caries S. salivarius and S. gordonii whereas S. sanguinis, S. mitis, S. sinensis, S. rubneri, S. vestibularis, S. cristatus and S. massiliensis were identified only in individuals with high caries. This study revealed the absence of R. mucilaginosa in the high caries subjects and its coexistence with the low caries subjects. Streptococcus mutans was insignificant contributor of caries among samples, while, Streptococcus sanguinis was the main constituent of high caries Saudi patients.     

Capsular Polysaccharide Surrounds Smooth and Rugose Types of Salmonella enterica serovar Typhimurium DT104

The biofilms and rugose colony morphology of Salmonella enterica serovar Typhimurium strains are usually associated with at least two different exopolymeric substances (EPS), curli and cellulose. In this study, another EPS, a capsular polysaccharide (CP) synthesized constitutively in S. enterica serovar Typhimurium strain DT104 at 25 and 37°C, has been recognized as a biofilm matrix component as well. Fluorophore-assisted carbohydrate electrophoresis (FACE) analysis indicated that the CP is comprised principally of glucose and mannose, with galactose as a minor constituent. The composition differs from that of known colanic acid-containing CP that is isolated from cells of Escherichia coli and other enteric bacteria grown at 37°C. The reactivity of carbohydrate-specific lectins conjugated to fluorescein isothiocyanate or gold particles with cellular carbohydrates demonstrated the cell surface localization of CP. Further, lectin binding also correlated with the FACE analysis of CP. Immunoelectron microscopy, using specific antibodies against CP, confirmed that CP surrounds the cells. Confocal microscopy of antibody-labeled cells showed greater biofilm formation at 25°C than at 37°C. Since the CP was shown to be produced at both 37°C and 25°C, it does not appear to be significantly involved in attachment during the early formation of the biofilm matrix. Although the attachment of S. enterica serovar Typhimurium DT104 does not appear to be mediated by its CP, the capsule does contribute to the biofilm matrix and may have a role in other features of this organism, such as virulence, as has been shown previously for the capsules of other gram-negative and gram-positive bacteria.     

First air-tolerant effective stainless steel microbial anode obtained from a natural marine biofilm

Microbial anodes were constructed with stainless steel electrodes under constant polarisation. The seawater medium was inoculated with a natural biofilm scraped from harbour equipment. This procedure led to efficient microbial anodes providing up to 4 A/m² for 10 mM acetate oxidation at −0.1 V/SCE. The whole current was due to the presence of biofilm on the electrode surface, without any significant involvement of the abiotic oxidation of sulphide or soluble metabolites. Using a natural biofilm as inoculum ensured almost optimal performance of the biofilm anode as soon as it was set up; the procedure also proved able to form biofilms in fully aerated media, which provided up to 0.7 A/m². The current density was finally raised to 8.2 A per square meter projected surface area using a stainless steel grid. The inoculating procedure used here combined with the control of the potential revealed, for the first time, stainless steel as a very competitive material for forming bioanodes with natural microbial consortia.     

Tolerance to drug-induced cell death favours the acquisition of multidrug resistance in Leishmania

The control of the protozoan parasite Leishmania relies on few drugs with unknown cellular targets and unclear mode of action. Several antileishmanials, however, were shown to induce apoptosis in Leishmania and this death mechanism was further studied in drug-sensitive and drug-resistant Leishmania infantum. In sensitive parasites, antimonials (SbIII), miltefosine (MF) and amphotericin B (AMB), but not paromomycin (PARO), triggered apoptotic cell death associated with reactive oxygen species (ROS). In contrast, Leishmania mutants resistant to SbIII, MF or AMB not only failed to undergo apoptosis following exposure to their respective drugs, but also were more tolerant towards apoptosis induced by other antileishmanials, provided that these killed Leishmania via ROS production. Such tolerance favored the rapid acquisition of multidrug resistance. PARO killed Leishmania in a non-apoptotic manner and failed to produce ROS. PARO resistance neither protected against drug-induced apoptosis nor provided an increased rate of acquisition of resistance to other antileishmanials. However, the PARO-resistant mutant, but not SbIII-, MF- or AMB-resistant mutants, became rapidly cross-resistant to methotrexate, a model drug also not producing ROS. Our results therefore link the mode of killing of drugs to tolerance to cell death and to a facilitated emergence of multidrug resistance. These findings may have fundamental implications in the field of chemotherapeutic interventions.     

Biofouling control using microparticles carrying a biocide

This study presents a new technological approach to minimize the use of antimicrobial (AMB) agents and their deleterious effects, based on the principle of drug-delivery systems whereby the AMB chemicals are transported on microparticles. The efficacy of microparticles carrying the quaternary ammonium compound (QAC), benzyldimethyldodecyl ammonium chloride (BDMDAC), was assessed against Pseudomonas fluorescens in both the planktonic and the biofilm state. The microparticles were prepared using a layer-by-layer (LBL) self-assembly technique. Oppositely charged molecules of polyethyleneimine (PEI), sodium polystyrene sulfonate (PSS), and BDMDAC were assembled on polystyrene (PS) cores. BDMDAC-coated particles were observed by CryoSEM and their composition analyzed by X-ray microanalysis. Zeta potential measurements indicated that changes in surface charge were compatible with a BDMDAC/particle interaction. This biocidal carrier structure had significant stability, verified by the release of only 15% of the BDMDAC when immersed in water for 18 months. Biocidal carrier activity was evaluated by determining the survival ratio of P. fluorescens planktonic and biofilm cells after different exposure periods to BDMDAC-coated particles. Tests with biofilm cells were also performed with the free QAC. An efficient AMB effect (minimum bactericidal concentration) against suspended cells was found for a concentration of 9.2 mg l^?1 of BDMDAC on coated particles after incubation for 30 min and 6.5 mg l^?1 of BDMDAC on coated particles after 60 min. Exposure of biofilms to PS-PEI/PSS/BDMDAC (0.87 mg l^?1) resulted in a decrease in viability of 60.5% and 66.5% of the total biofilm population for 30 and 60 min exposure times, respectively. Exposure for 60 min to 6.33 mg l^?1 and 11.75 mg l^?1 of BDMDAC in PS-PEI/PSS/BDMDAC particles promoted inactivation of 80.6% and 87.2% of the total population, respectively. The AMB effects obtained with the application of free BDMDAC were statistically similar to those promoted by the application of BDMDAC coated particles. The overall results indicate that this novel AMB strategy has potential for the control of microbial growth of planktonic cells and biofouling. Moreover, the technique allows the reuse of AMB molecules and consequently reduces the environmental risks associated with excessive use of AMB agents, thereby providing real benefits to public health.     

Comparative evaluation of different carrier-based multi-strain bacterial formulations to mitigate the salt stress in wheat

The application of liquid bacterial consortia to soil under natural conditions may fail due to various environmental constraints. In this study, the suitability and efficiency of compost, biogas slurry, crushed corn cob, and zeolite as carriers to support the survival of plant growth-promoting rhizobacteria (PGPR) and improve the performance of multi-strain bacterial consortia to mitigate the effects of salinity stress on wheat under pot conditions were evaluated. The survival of strains of Pseudomonas putida, Serratia ficaria, and Pseudomonas fluorescens labelled with gusA was evaluated for up to 90 days. Seeds coated with different carrier-based formulations of multi-strain consortia were sown in pots at three different salinity levels (1.53, 10, and 15 dS m⁻¹). Results showed that salinity stress significantly reduced wheat growth, yield, gas exchange, and ionic and biochemical parameter values, but the 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing multi-strain consortium used mitigated the inhibitory effects of salinity on plant growth and yield parameters. However, carrier-based inoculation further improved the efficacy of multi-strain consortium inoculation and significantly (P < 0.05) increased the growth, yield, and physiological parameters value of wheat at all salinity levels. On the basis of the observed trends in survival and the outcomes of the pot trials, the inoculation of multi-strain consortia in compost and biogas slurry carriers resulted in more successful wheat growth under salinity stress compared to that in the rest of the treatments tested.     

Synthetic Escherichia coli consortia engineered for syntrophy demonstrate enhanced biomass productivity

Synthetic Escherichia coli consortia engineered for syntrophy demonstrated enhanced biomass productivity relative to monocultures. Binary consortia were designed to mimic a ubiquitous, naturally occurring ecological template of primary productivity supported by secondary consumption. The synthetic consortia replicated this evolution-proven strategy by combining a glucose positive E. coli strain, which served as the system's primary producer, with a glucose negative E. coli strain which consumed metabolic byproducts from the primary producer. The engineered consortia utilized strategic division of labor to simultaneously optimize multiple tasks enhancing overall culture performance. Consortial interactions resulted in the emergent property of enhanced system biomass productivity which was demonstrated with three distinct culturing systems: batch, chemostat and biofilm growth. Glucose-based biomass productivity increased by ∼15, 20 and 50% compared to appropriate monoculture controls for these three culturing systems, respectively. Interestingly, the consortial interactions also produced biofilms with predictable, self-assembling, laminated microstructures. This study establishes a metabolic engineering paradigm which can be easily adapted to existing E. coli based bioprocesses to improve productivity based on a robust ecological theme.     

Compost-Induced Suppression of Pythium Damping-Off Is Mediated by Fatty-Acid-Metabolizing Seed-Colonizing Microbial Communities

Leaf composts were studied for their suppressive effects on Pythium ultimum sporangium germination, cottonseed colonization, and the severity of Pythium damping-off of cotton. A focus of the work was to assess the role of fatty-acid-metabolizing microbial communities in disease suppression. Suppressiveness was expressed within the first few hours of seed germination as revealed by reduced P. ultimum sporangium germination, reduced seed colonization, and reduced damping-off in transplant experiments. These reductions were not observed when cottonseeds were sown in a conducive leaf compost. Microbial consortia recovered from the surface of cottonseeds during the first few hours of germination in suppressive compost (suppressive consortia) induced significant levels of damping-off suppression, whereas no suppression was induced by microbial consortia recovered from cottonseeds germinated in conducive compost (conducive consortia). Suppressive consortia rapidly metabolized linoleic acid, whereas conducive consortia did not. Furthermore, populations of fatty-acid-metabolizing bacteria and actinobacteria were higher in suppressive consortia than in conducive consortia. Individual bacterial isolates varied in their ability to metabolize linoleic acid and protect seedlings from damping-off. Results indicate that communities of compost-inhabiting microorganisms colonizing cottonseeds within the first few hours after sowing in a Pythium-suppressive compost play a major role in the suppression of P. ultimum sporangium germination, seed colonization, and damping-off. Results further indicate that fatty acid metabolism by these seed-colonizing bacterial consortia can explain the Pythium suppression observed.     

Evaluating the Metal Tolerance Capacity of Microbial Communities Isolated from Alberta Oil Sands Process Water

Anthropogenic activities have resulted in the intensified use of water resources. For example, open pit bitumen extraction by Canada’s oil sands operations uses an estimated volume of three barrels of water for every barrel of oil produced. The waste tailings–oil sands process water (OSPW)–are stored in holding ponds, and present an environmental concern as they are comprised of residual hydrocarbons and metals. Following the hypothesis that endogenous OSPW microbial communities have an enhanced tolerance to heavy metals, we tested the capacity of planktonic and biofilm populations from OSPW to withstand metal ion challenges, using Cupriavidus metallidurans, a known metal-resistant organism, for comparison. The toxicity of the metals toward biofilm and planktonic bacterial populations was determined by measuring the minimum biofilm inhibitory concentrations (MBICs) and planktonic minimum inhibitory concentrations (MICs) using the MBEC ™ assay. We observed that the OSPW community and C. metallidurans had similar tolerances to 22 different metals. While thiophillic elements (Te, Ag, Cd, Ni) were found to be most toxic, the OSPW consortia demonstrated higher tolerance to metals reported in tailings ponds (Al, Fe, Mo, Pb). Metal toxicity correlated with a number of physicochemical characteristics of the metals. Parameters reflecting metal-ligand affinities showed fewer and weaker correlations for the community compared to C. metallidurans, suggesting that the OSPW consortia may have developed tolerance mechanisms toward metals present in their environment.     

Effect of herbicide adjuvants on the biodegradation rate of the methylthiotriazine herbicide prometryn

A microbial community, selected by its ability to degrade triazinic herbicides was acclimatized by successive transfers in batch cultures. Initially, its ability to degrade prometryn, was evaluated using free cells or cells attached to fragments of a porous support. As carbon, nitrogen and sulfur sources, prometryn, (98.8 % purity), or Gesagard, a herbicide formulation containing 44.5 % prometryn and 65.5 % of adjuvants, were used. In batch cultures, a considerable delay in the degradation of prometryn, presumptively caused by the elevated concentration of inhibitory adjuvants, occurred. When pure prometryn was used, volumetric removal rates remarkably higher than those obtained with the herbicide formulation were estimated by fitting the raw experimental data to sigmoidal decay models, and differentiating them. When the microbial consortium was immobilized in a continuously operated biofilm reactor, the negative effect of adjuvants on the rate and removal efficiency of prometryn could not be detected. Using the herbicide formulation, the consortium showed volumetric removal rates greater than 20 g m^?3 h^?1, with prometryn removal efficiencies of 100 %. The predominant bacterial strains isolated from the microbial consortium were Microbacterium sp., Enterobacter sp., Acinetobacter sp., and Flavobacterium sp. Finally, by comparison of the prometryn removal rates with others reported in the literature, it can be concluded that the use of microbial consortia immobilized in a biofilm reactor operated in continuous regime offer better results than batch cultures of pure microbial strains.     

In vitro activity of the lipopeptide PAL-Lys-Lys-NH2, alone and in combination with antifungal agents, against clinical isolates of Candida spp

Candida albicans is known to be the organism most often associated with serious fungal infection, but other Candida spp. are emerging as clinical pathogens associated with opportunistic infections. Among antimycotic treatments, increasing attention is currently given to anti-infective drugs based upon naturally occurring peptides, such as the short lipopeptide palmitoyl PAL-Lys-Lys-NH2 (PAL). The aim of this study is to evaluate the activity of this peptide compared to the traditional antifungal agents Fluconazole (FLU), amphotericin B (AMB) and caspofungin (CAS) on Candida spp. 24 clinical isolates of Candida spp. were tested against PAL_, FLU, AMB and CAS using in vitro susceptibility tests, time killing and checkerboard assay. All of the drugs studied showed good activity against clinical isolates of candida; in particular CAS and AMB which have MICs value lower than PAL and FLU. Moreover we observed synergistic interactions for PAL/FLU (81.25%), PAL/AMB (75%) and particularly for PAL/CAS (87.5). We think that our results are interesting since synergy between PAL and CAS might be useful in clinic trails to treat invasive fungal infections.