Structural and Functional Insights into the Biofilm-Associated BceF Tyrosine Kinase Domain from Burkholderia cepacia.

BceF is a bacterial tyrosine kinase (BY-kinase) from Burkholderia cepacia, a Gram-negative bacterium accountable for respiratory infections in immunocompromised and cystic fibrosis patients. BceF is involved in the production of exopolysaccharides secreted to the biofilm matrix and promotes resistant and aggressive infections. BY-kinases share no homology with mammalian kinases, and thereby offer a means to develop novel and specific antivirulence drugs. Here, we report the crystal structure of the BceF kinase domain at 1.85 Å resolution. The isolated BceF kinase domain is assembled as a dimer in solution and crystallized as a dimer in the asymmetric unit with endogenous adenosine-diphosphate bound at the active sites. The low enzymatic efficiency measured in solution may be explained by the partial obstruction of the active sites at the crystallographic dimer interface. This study provides insights into self-assembly and the specific activity of isolated catalytic domains. Several unique variations around the active site compared to other BY-kinases may allow for structure-based design of specific inhibitors to target Burkholderia cepacia virulence.

Diffuse lamellar keratitis associated with tabletop autoclave biofilms: case series and review.

PURPOSE: To report a diffuse lamellar keratitis (DLK) cluster attributed to autoclave reservoir biofilm and to review the risk and prevention of DLK and toxic anterior segment syndrome (TASS) caused by such biofilms. SETTING: Refractive Surgery Center, University of California, Berkeley. DESIGN: Observational case-control study and review of literature. METHODS: Eyes were evaluated for DLK following laser in situ keratomileusis (LASIK) over a 5-year period. Multiple changes in surgical and operating room protocols were prompted by a cluster of DLK cases. The autoclave reservoir chamber wall was cultured for microbial contamination. The MEDLINE database was used to identify relevant past publications. RESULTS: From January 7, 2010, to December 18, 2014, 1115 eyes received LASIK. Between September 2, 2010, and June 11, 2012, 147 eyes of 395 LASIK cases developed DLK (37.2%). Systematic modifications in surgical protocols were unsuccessful in ending the prolonged cluster of DLK cases until the STATIM 2000 autoclave was replaced with a new STATIM autoclave and a reservoir sterilization and surveillance protocol implemented. Over the subsequent 30 months, DLK incidence was reduced to 2.2% (14 DLK cases from 632 total LASIK cases, P < .0001). The retired autoclave reservoir chamber wall cultures grew Pseudomonas aeruginosa and the Burkholderia cepacia complex. CONCLUSIONS: Fluid reservoirs of tabletop steam autoclaves can readily develop polymicrobial biofilms harboring microbial pathogens, whose inert molecular byproducts can cause DLK and TASS when introduced to the eye by surgical instruments. Stringent reservoir cleaning and maintenance may significantly reduce this risk by preventing and removing these biofilms.

Beneficial effects of inoculation of growth-promoting bacteria in strawberry.

Plant growth-promoting bacteria have been highlighted by their potential for application in plant production, allowing the reduction of the use of fertilizers and pesticides, which is due to the ability to stimulate the growth of plants by nitrogen-fixation and production of phytohormones, such as indole-3-acetic acid (IAA). The objective of this study was to verify the potential of plant growth promotion of 25 wild isolates from the Agricultural Microbiology Culture Collection of the Federal University of Lavras (CCMA-UFLA) through the evaluation of the biological nitrogen-fixation capacity and the production of IAA. In addition, the growth of three selected strains inoculated on roots of strawberry seedlings in greenhouse conditions was evaluated. The experiment was conducted in a completely randomized design (CRD), with an 8 × 2 factorial schemes involving eight combinations of bacteria: alone, in pairs and threes, plus the control without inoculation. Two fertilizer levels were used (0% and 50% of nitrogen), totaling 16 treatments with eight replicates each. After 75 days, variables such as root length, root dry weight, aerial part length, aerial part dry weight, leaf number, total dry mass and ultrastructural analysis of the inoculated and uninoculated roots, were evaluated. The results showed that the strawberry crop responded positively to inoculation with the three bacteria combined Azospirillum brasilense (Ab-V5) + Burkholderia cepacia (CCMA 0056) + Enterobacter cloacae (CCMA 1285) compared to the uninoculated controls. More expressive responses in terms of plant growth were observed in relation to the combined inoculation of the three bacterial strains plus fertilizer application with 50% of nitrogen.

Natural killer cells kill Burkholderia cepacia complex via a contact-dependent and cytolytic mechanism.

Burkholderia cepacia complex (Bcc), which includes B. cenocepacia and B. multivorans, pose a life-threatening risk to patients with cystic fibrosis. Eradication of Bcc is difficult due to the high level of intrinsic resistance to antibiotics, and failure of many innate immune cells to control the infection. Because of the pathogenesis of Bcc infections, we wondered if a novel mechanism of microbial host defense involving direct antibacterial activity by natural killer (NK) cells might play a role in the control of Bcc. We demonstrate that NK cells bound Burkholderia, resulting in Src family kinase activation as measured by protein tyrosine phosphorylation, granule release of effector proteins such as perforin and contact-dependent killing of the bacteria. These studies provide a means by which NK cells could play a role in host defense against Bcc infection.

Pseudomonas and Burkholderia inhibit growth and asexual development of Phytophthora capsici.

The objective of this study was to isolate and characterize antagonistic rhizobacteria from chili against a notorious phytopathogen Phytophthora capsici. Among the 48 bacteria isolated, BTLbbc-02, BTLbbc-03, and BTLbbc-05 were selected based on their inhibitory activity against P. capsici. They were tentatively identified as Burkholderia metallica BTLbbc-02, Burkholderia cepacia BTLbbc-03, and Pseudomonas aeruginosa BTLbbc-05, respectively, based on their 16S rRNA gene sequencing. All inhibited the growth of P. capsici at varying levels by inducing characteristic morphological alterations of P. capsici hyphae. The cell-free culture supernatant of all three isolates impaired motility (up to 100%) and caused lysis (up to 50%) of the halted zoospores. Bioassays revealed that Pseudomonas sp. had higher antagonism and zoospore motility-inhibitory effects against P. capsici compared with two other isolates, Burkholderia spp. and B. metallica, which caused vacuolation in mycelium. All three bacteria suppressed sporangium formation and zoosporogenesis of P. capsici, and improved the seed germination and growth of cucumber. Our findings suggest that epiphytic bacteria, B. metallica, B. cepacia, and P. aeruginosa, could be used as potential biocontrol agents against P. capsici. A further study is required to ensure conformity with the existing regulations for soil, plant, and human health.

Multiscale Model Describing Bacterial Adhesion and Detachment.

Bacterial surfaces are complex structures with nontrivial adhesive properties. The physics of bacterial adhesion deviates from that of ideal colloids as a result of cell-surface roughness and because of the mechanical properties of the polymers covering the cell surface. In the present study, we develop a simple multiscale model for the interplay between the potential energy functions that characterize the cell surface biopolymers and their interaction with the extracellular environment. We then use the model to study a discrete network of bonds in the presence of significant length heterogeneities in cell-surface polymers. The model we present is able to generate force curves (both approach and retraction) that closely resemble those measured experimentally. Our results show that even small-length-scale heterogeneities can lead to macroscopically nonlinear behavior that is qualitatively and quantitatively different from the homogeneous case. We also report on the energetic consequences of such structural heterogeneity.

Control of Attachment of Pseudomonas aeruginosa and Burkholderia cepacia to Surfaces by Shear Force.

The effect of physical shearing on the attachment of six Pseudomonas aeruginosa strains and six Burkholderia cepacia strains to glass, stainless steel, polystyrene and Teflon® was determined. A significant (p < 0.05) decrease in hydrophobicity was apparent for all P. aeruginosa strains (17-36%) and B. cepacia, MS 5 (20%) after shearing. A significant (p < 0.05) decrease in attachment of some P. aeruginosa (0.2-0.5 log CFU/cm2) and B. cepacia (0.2-0.4 log CFU/cm2) strains to some surface types was apparent after shearing. Significant (p < 0.05) correlation was observed for both numbers of flagellated cells and hydrophobicity against attachment to glass, stainless steel and polystyrene for P. aeruginosa while only hydrophobicity showed significant correlation against the same surfaces for B. cepacia. Scanning electron microscopy and protein analysis showed that shearing removed surface proteins from the cells and may have led to the observed changes in hydrophobicity and attachment to abiotic surfaces.

Exposure to extremely low-frequency magnetic field affects biofilm formation by cystic fibrosis pathogens.

AIMS: To evaluate the in vitro effects of extremely low-frequency magnetic field (ELF-MF) on growth and biofilm formation by Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia and Stenotrophomonas maltophilia strains from cystic fibrosis patients. MATERIALS & METHODS: The motion of selected ions (Fe, Ca, Cu, Zn, Mg, K, Na) was stimulated by the ion resonance effect, then influence on growth and biofilm formation/viability was assessed by spectrophotometry or viability count. RESULTS: Generally, exposure to ELF-MF significantly increased bacterial growth and affected both biofilm formation and viability, although with differences with regard to ions and species considered. CONCLUSION: Exposure to ELF-MF represents a possible new approach for treatment of biofilm-associated cystic fibrosis lung infections.

Localization of Burkholderia cepacia complex bacteria in cystic fibrosis lungs and interactions with Pseudomonas aeruginosa in hypoxic mucus.

The localization of Burkholderia cepacia complex (Bcc) bacteria in cystic fibrosis (CF) lungs, alone or during coinfection with Pseudomonas aeruginosa, is poorly understood. We performed immunohistochemistry for Bcc and P. aeruginosa bacteria on 21 coinfected or singly infected CF lungs obtained at transplantation or autopsy. Parallel in vitro experiments examined the growth of two Bcc species, Burkholderia cenocepacia and Burkholderia multivorans, in environments similar to those occupied by P. aeruginosa in the CF lung. Bcc bacteria were predominantly identified in the CF lung as single cells or small clusters within phagocytes and mucus but not as "biofilm-like structures." In contrast, P. aeruginosa was identified in biofilm-like masses, but densities appeared to be reduced during coinfection with Bcc bacteria. Based on chemical analyses of CF and non-CF respiratory secretions, a test medium was defined to study Bcc growth and interactions with P. aeruginosa in an environment mimicking the CF lung. When test medium was supplemented with alternative electron acceptors under anaerobic conditions, B. cenocepacia and B. multivorans used fermentation rather than anaerobic respiration to gain energy, consistent with the identification of fermentation products by high-performance liquid chromatography (HPLC). Both Bcc species also expressed mucinases that produced carbon sources from mucins for growth. In the presence of P. aeruginosa in vitro, both Bcc species grew anaerobically but not aerobically. We propose that Bcc bacteria (i) invade a P. aeruginosa-infected CF lung when the airway lumen is anaerobic, (ii) inhibit P. aeruginosa biofilm-like growth, and (iii) expand the host bacterial niche from mucus to also include macrophages.

Species-specific viability analysis of Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus in mixed culture by flow cytometry.

BACKGROUND: Bacterial species coexist commonly in mixed communities, for instance those occurring in microbial infections of humans. Interspecies effects contribute to alterations in composition of communities with respect to species and thus, to the course and severity of infection. Therefore, knowledge concerning growth and viability of single species in medically-relevant mixed communities is of high interest to resolve complexity of interspecies dynamics and to support development of treatment strategies. In this study, a flow cytometric method was established to assess the species-specific viability in defined three-species mixed cultures. The method enables the characterization of viability of Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus, which are relevant to lung infections of Cystic Fibrosis (CF) patients. The method combines fluorescence detection by antibody and lectin labeling with viability fluorescence staining using SYBRGreen I and propidium iodide. In addition, species-specific cell enumeration analysis using quantitative terminal restriction fragment length polymorphisms (qT-RFLP) was used to monitor the growth dynamics. Finally, to investigate the impact of substrate availability on growth and viability, concentrations of main substrates and metabolites released were determined. RESULTS: For each species, the time course of growth and viability during mixed culture cultivations was obtained by using qT-RFLP analysis in combination with flow cytometry. Comparison between mixed and pure cultures revealed for every species differences in growth properties, e.g. enhanced growth of P. aeruginosa in mixed culture. Differences were also observed for B. cepacia and S. aureus in the time course of viability, e.g. an early and drastic reduction of viability of S. aureus in mixed culture. Overall, P. aeruginosa clearly dominated the mixed culture with regard to obtained cell concentrations. CONCLUSIONS: In combination with qT-RFLP analysis, the methods enabled monitoring of species-specific cell concentrations and viability during co-cultivation of theses strains. Experimental findings suggest that the predominance of P. aeruginosa over B. cepacia and S. aureus in mixed culture under the chosen cultivation conditions is promoted by more efficient substrate consumption of P. aeruginosa, and antagonistic interspecies effects induced by P. aeruginosa.

Transport of nanoparticles and tobramycin-loaded liposomes in Burkholderia cepacia complex biofilms.

Due to the intrinsic resistance of Burkholderia cepacia complex (Bcc) to many antibiotics and the production of a broad range of virulence factors, lung infections by these bacteria, primarily occurring in cystic fibrosis (CF) patients, are very difficult to treat. In addition, the ability of Bcc organisms to form biofilms contributes to their persistence in the CF lung. As Bcc infections are associated with poor clinical outcome, there is an urgent need for new effective therapies to treat these infections. In the present study, we investigated whether liposomal tobramycin displayed an increased anti-biofilm effect against Bcc bacteria compared to free tobramycin. Single particle tracking (SPT) was used to study the transport of positively and negatively charged nanospheres in Bcc biofilms as a model for the transport of liposomes. Negatively charged nanospheres became immobilized in close proximity of biofilm cell clusters, while positively charged nanospheres interacted with fiber-like structures, probably eDNA. Based on these data, encapsulation of tobramycin in negatively charged liposomes appeared promising for targeted drug delivery. However, the anti-biofilm effect of tobramycin encapsulated into neutral or anionic liposomes did not increase compared to that of free tobramycin. Probably, the fusion of the anionic liposomes with the negatively charged bacterial surface of Bcc bacteria was limited by electrostatic repulsive forces. The lack of a substantial anti-biofilm effect of tobramycin encapsulated in neutral liposomes could be further investigated by increasing the liposomal tobramycin concentration. However, this was hampered by the low encapsulation efficiency of tobramycin in these liposomes.

Infection of Burkholderia cepacia induces homeostatic responses in the host for their prolonged survival: the microarray perspective.

Burkholderia cepacia is an opportunistic human pathogen associated with life-threatening pulmonary infections in immunocompromised individuals. Pathogenesis of B. cepacia infection involves adherence, colonisation, invasion, survival and persistence in the host. In addition, B. cepacia are also known to secrete factors, which are associated with virulence in the pathogenesis of the infection. In this study, the host factor that may be the cause of the infection was elucidated in human epithelial cell line, A549, that was exposed to live B. cepacia (mid-log phase) and its secretory proteins (mid-log and early-stationary phases) using the Illumina Human Ref-8 microarray platform. The non-infection A549 cells were used as a control. Expression of the host genes that are related to apoptosis, inflammation and cell cycle as well as metabolic pathways were differentially regulated during the infection. Apoptosis of the host cells and secretion of pro-inflammatory cytokines were found to be inhibited by both live B. cepacia and its secretory proteins. In contrast, the host cell cycle and metabolic processes, particularly glycolysis/glycogenesis and fatty acid metabolism were transcriptionally up-regulated during the infection. Our microarray analysis provided preliminary insights into mechanisms of B. cepacia pathogenesis. The understanding of host response to an infection would provide novel therapeutic targets both for enhancing the host's defences and repressing detrimental responses induced by the invading pathogen.

Biofilm-grown Burkholderia cepacia complex cells survive antibiotic treatment by avoiding production of reactive oxygen species.

The presence of persister cells has been proposed as a factor in biofilm resilience. In the present study we investigated whether persister cells are present in Burkholderia cepacia complex (Bcc) biofilms, what the molecular basis of antimicrobial tolerance in Bcc persisters is, and how persisters can be eradicated from Bcc biofilms. After treatment of Bcc biofilms with high concentrations of various antibiotics often a small subpopulation survived. To investigate the molecular mechanism of tolerance in this subpopulation, Burkholderia cenocepacia biofilms were treated with 1024 µg/ml of tobramycin. Using ROS-specific staining and flow cytometry, we showed that tobramycin increased ROS production in treated sessile cells. However, approximately 0.1% of all sessile cells survived the treatment. A transcriptome analysis showed that several genes from the tricarboxylic acid cycle and genes involved in the electron transport chain were downregulated. In contrast, genes from the glyoxylate shunt were upregulated. These data indicate that protection against ROS is important for the survival of persisters. To confirm this, we determined the number of persisters in biofilms formed by catalase mutants. The persister fraction in ΔkatA and ΔkatB biofilms was significantly reduced, confirming the role of ROS detoxification in persister survival. Pretreatment of B. cenocepacia biofilms with itaconate, an inhibitor of isocitrate lyase (ICL), the first enzyme in the glyoxylate shunt, reduced the persister fraction approx. 10-fold when the biofilms were subsequently treated with tobramycin. In conclusion, most Bcc biofilms contain a significant fraction of persisters that survive treatment with high doses of tobramycin. The surviving persister cells downregulate the TCA cycle to avoid production of ROS and at the same time activate an alternative pathway, the glyoxylate shunt. This pathway may present a novel target for combination therapy.

Comparative transcriptomic analysis of the Burkholderia cepacia tyrosine kinase bceF mutant reveals a role in tolerance to stress, biofilm formation, and virulence.

The bacterial tyrosine-kinase (BY-kinase) family comprises the major group of bacterial enzymes endowed with tyrosine kinase activity. We previously showed that the BceF protein from Burkholderia cepacia IST408 belongs to this BY-kinase family and is involved in the biosynthesis of the exopolysaccharide cepacian. However, little is known about the extent of regulation of this protein kinase activity. In order to examine this regulation, we performed a comparative transcriptome profile between the bceF mutant and wild-type B. cepacia IST408. The analyses led to identification of 630 genes whose expression was significantly changed. Genes with decreased expression in the bceF mutant were related to stress response, motility, cell adhesion, and carbon and energy metabolism. Genes with increased expression were related to intracellular signaling and lipid metabolism. Mutation of bceF led to reduced survival under heat shock and UV light exposure, reduced swimming motility, and alteration in biofilm architecture when grown in vitro. Consistent with some of these phenotypes, the bceF mutant demonstrated elevated levels of cyclic-di-GMP. Furthermore, BceF contributed to the virulence of B. cepacia for larvae of the Greater wax moth, Galleria mellonella. Taken together, BceF appears to play a considerable role in many cellular processes, including biofilm formation and virulence. As homologues of BceF occur in a number of pathogenic and plant-associated Burkholderia strains, the modulation of bacterial behavior through tyrosine kinase activity is most likely a widely occurring phenomenon.

Cellulase inhibits Burkholderia cepacia biofilms on diverse prosthetic materials.

Burkholderia cepacia is an opportunistic pathogen causing infections in patients with cystic fibrosis. Patients with implanted devices are prone to B. cepacia infections due to its ability to grow as biofilms. Knowing the importance of polysaccharides in a biofilm, enzymes that degrade them were targeted as a possible candidate for antibiofilm agents. In this study, the antibiofilm potential of cellulase against B. cepacia biofilms formed on various prosthetic materials was tested. Cellulase exhibited significant antibiofilm activity against B. cepacia without having much action on its growth, thus ruling out the chance of selection pressure and subsequent development resistance.

Draft genome sequence of the volatile organic compound-producing Antarctic bacterium Arthrobacter sp. strain TB23, able to inhibit cystic fibrosis pathogens belonging to the Burkholderia cepacia complex.

Arthrobacter sp. strain TB23 was isolated from the Antarctic sponge Lissodendoryx nobilis. This bacterium is able to produce antimicrobial compounds and volatile organic compounds (VOCs) that inhibit the growth of other Antarctic bacteria and of cystic fibrosis opportunistic pathogens, respectively. Here we report the draft genome sequence of Arthrobacter sp. TB23.

[Burkholderia cepacia persistence in patients with mucoviscidosis].

AIM: Study features of persistence of Burkholderia cepacia in mucoviscidosis patients. MATERIALS AND METHODS: In the period from 2008 to 2009, 56 B. cepacia strains isolated from children with mucoviscidosis were obtained. 114 medical histories of children with mucoviscidosis from various age groups were analyzed. The developed algorithm for identification and typing including phenotype and molecular biology methods was used to identify B. cepacia bacteria. Strain genotyping was carried out by RAPD-PCR with random oligonucleotide primer as well as pulse-electrophoresis. RESULTS: Persistence of associations ofmicroogranisms in 59.4% of cases was established to be the feature of persistent infection in mucoviscidosis. The feature of persistence of B. cepacia strains in patients with diagnosis ofmuco-viscidosis mixed form, severe course is persistence in association with Pseudomonas aeruginosa. B. cepacia bacteria that can persist in mucoviscidosis patients are characterized by resistance to many antibiotics. A prolonged (up to 1 year and 5 months) persistence of B. cepacia strains isolated from 1 patient was proven by using microflora monitoring of lower respiratory tract. CONCLUSION: B. cepacia bacteria may colonize lower respiratory tract of mucoviscidosis patients, persist for a long time and be transmitted between patients.

Impact of an extracellular polymeric substance (EPS) precoating on the initial adhesion of Burkholderia cepacia and Pseudomonas aeruginosa.

Extracellular polymeric substances (EPS) significantly influence bacterial adhesion to solid surfaces, but it is difficult to elucidate the role of EPS on bacterial adhesion due to their complexity and variability. In the present study, the effect of EPS on the initial adhesion of B. cepaciaepacia PC184 and P. aeruginosa PAO1 on glass slides with and without an EPS precoating was investigated under three ionic strength conditions. The surface roughness of EPS coated slides was evaluated by atomic force microscopy (AFM), and its effect on initial bacterial adhesion was found to be trivial. X-ray photoelectron spectroscopy (XPS) studies were performed to determine the elemental surface compositions of bacterial cells and substrata. The results showed that an EPS precoating hindered bacterial adhesion on solid surfaces, which was largely attributed to the presence of proteins in the EPS. This observation can be attributed to the increased steric repulsion at high ionic strength conditions. A steric model for polymer brushes that considers the combined influence of steric effects and DLVO interaction forces is shown to adequately describe bacterial adhesion behaviors.

Impact of cranberry juice on initial adhesion of the EPS producing bacterium Burkholderia cepacia.

The impact of cranberry juice was investigated with respect to the initial adhesion of three isogenic strains of the bacterium Burkholderia cepacia with different extracellular polymeric substance (EPS) producing capacities, viz. a wild-type cepacian EPS producer PC184 and its mutant strains PC184rml with reduced EPS production and PC184bceK with a deficiency in EPS production. Adhesion experiments conducted in a parallel-plate flow chamber demonstrated that, in the absence of cranberry juice, strain PC184 had a significantly higher adhesive capacity compared to the mutant strains. In the presence of cranberry juice, the adhesive capacity of the EPS-producing strain PC184 was largely reduced, while cranberry juice had little impact on the adhesion behavior of either mutant strain. Thermodynamic modeling supported the results from adhesion experiments. Surface force apparatus (SFA) and scanning electron microscope (SEM) studies demonstrated a strong association between cranberry juice components and bacterial EPS. It was concluded that cranberry juice components could impact bacterial initial adhesion by adhering to the EPS and impairing the adhesive capacity of the cells, which provides an insight into the development of novel treatment strategies to block the biofilm formation associated with bacterial infection.

Use of two bacteria for biological control of bayoud disease caused by Fusarium oxysporum in date palm (Phoenix dactylifera L) seedlings.

The Bayoud, caused by Fusarium oxysporum f. sp. albedinis (Foa), is the most destructive disease of date palm (Phoenix dactylifera L) in Morocco and Algeria, with no effective control strategy yet available. In this work, two bacteria, Bacillus amyloliquefaciens strain Ag1 (Ag) and Burkholderia cepacia strain Cs5 (Cs), were examined for their potential to control this disease. Both bacterial strains inhibited both growth and sporulation of Foa. They released compounds into the culture medium, which resulted into cytological changes in Foa's mycelial structure. When Jihel-date palm plantlets, a susceptible cultivar, were induced with these bacteria, the size of the necrosis zone, which reflected the spreading of the pathogen, was reduced by more than 70%, as compared with uninduced controls. To further investigate the mechanisms of such disease reduction, phenolic compounds and peroxidase activity were assessed. One month after inoculation, date palm defense reactions against Foa were different depending on the bacterium used, B. cepacia led to higher accumulation of constitutive caffeoylshikimic acid isomers while B. amyloliquefaciens triggered the induction of new phenolic compounds identified as hydroxycinnamic acid derivatives. Peroxidase activity has also been stimulated significantly and varied with the bacterial strain used and with Foa inoculation. These results add to the promising field of investigation in controlling Bayoud disease.