Loss of Function inEscherichia coliExposed to Environmentally Relevant Concentrations of Benzalkonium Chloride

ABSTRACTAssessing the risk of resistance associated with biocide exposure commonly involves exposing microorganisms to biocides at concentrations close to the MIC. With the aim of representing exposure to environmental biocide residues,Escherichia coliMG1655 was grown for 20 passages in the presence or absence of benzalkonium chloride (BAC) at 100 ng/liter and 1,000 ng/liter (0.0002% and 0.002% of the MIC, respectively). BAC susceptibility, planktonic growth rates, motility, and biofilm formation were assessed, and differentially expressed genes were determined via transcriptome sequencing. Planktonic growth rate and biofilm formation were significantly reduced (P< 0.001) following BAC adaptation, while BAC minimum bactericidal concentration increased 2-fold. Transcriptomic analysis identified 289 upregulated and 391 downregulated genes after long-term BAC adaptation compared with the respective control organism passaged in BAC-free medium. When the BAC-adapted bacterium was grown in BAC-free medium, 1,052 genes were upregulated and 753 were downregulated. Repeated passage solely in biocide-free medium resulted in 460 upregulated and 476 downregulated genes compared with unexposed bacteria. Long-term exposure to environmentally relevant BAC concentrations increased the expression of genes associated with efflux and reduced the expression of genes associated with outer-membrane porins, motility, and chemotaxis. This was manifested phenotypically through the loss of function (motility). Repeated passage in a BAC-free environment resulted in the upregulation of multiple respiration-associated genes, which was reflected by increased growth rate. In summary, repeated exposure ofE. colito BAC residues resulted in significant alterations in global gene expression that were associated with minor decreases in biocide susceptibility, reductions in growth rate and biofilm formation, and loss of motility.IMPORTANCEExposure to very low concentrations of biocides in the environment is a poorly understood risk factor for antimicrobial resistance. Repeated exposure to trace levels of the biocide benzalkonium chloride (BAC) resulted in loss of function (motility) and a general reduction in bacterial fitness but relatively minor decreases in susceptibility. These changes were accompanied by widespread changes in theEscherichia colitranscriptome. These results demonstrate the importance of including phenotypic characterization in studies designed to assess the risks of biocide exposure.

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Attenuated Virulence and Biofilm Formation in Staphylococcus aureus following Sublethal Exposure to Triclosan

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05904-11 ◽

2012 ◽

Vol 56 (6) ◽

pp. 3092-3100 ◽

Cited By ~ 47

Author(s):

Joe Latimer ◽

Sarah Forbes ◽

Andrew J. McBain

Keyword(s):

Staphylococcus Aureus ◽

Growth Rate ◽

Growth Rates ◽

Biofilm Formation ◽

Galleria Mellonella ◽

Concentration Gradients ◽

Content Type ◽

Small Colony Variant ◽

Small Colony ◽

Repeated Passage

ABSTRACTSubeffective exposure ofStaphylococcus aureusto the biocide triclosan can reportedly induce a small-colony variant (SCV) phenotype.S. aureusSCVs are characterized by low growth rates, reduced pigmentation, and lowered antimicrobial susceptibility. While they may exhibit enhanced intracellular survival, there are conflicting reports regarding their pathogenicity. The current study reports the characteristics of an SCV-like strain ofS. aureuscreated by repeated passage on sublethal triclosan concentrations.S. aureusATCC 6538 (the passage 0 [P0] strain) was serially exposed 10 times to concentration gradients of triclosan to generate strain P10. This strain was then further passaged 10 times on triclosan-free medium (designated strain ×10). The MICs and minimum bactericidal concentrations of triclosan for P0, P10, and ×10 were determined, and growth rates in biofilm and planktonic cultures were measured. Hemolysin, DNase, and coagulase activities were measured, and virulence was determined using aGalleria mellonellapathogenicity model. Strain P10 exhibited decreased susceptibility to triclosan and characteristics of an SCV phenotype, including a considerably reduced growth rate and the formation of pinpoint colonies. However, this strain also had delayed coagulase production, had impaired hemolysis (P< 0.01), was defective in biofilm formation and DNase activity, and displayed significantly attenuated virulence. Colony size, hemolysis, coagulase activity, and virulence were only partially restored in strain ×10, whereas the planktonic growth rate was fully restored. However, ×10 was at least as defective in biofilm formation and DNase production as P10. These data suggest that although repeated exposure to triclosan may result in an SCV-like phenotype, this is not necessarily associated with increased virulence and adapted bacteria may exhibit other functional deficiencies.

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Biocide Exposure Induces Changes in Susceptibility, Pathogenicity, and Biofilm Formation in Uropathogenic Escherichia coli

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01892-18 ◽

2019 ◽

Vol 63 (3) ◽

Cited By ~ 8

Author(s):

E. L. Henly ◽

J. A. R. Dowling ◽

J. B. Maingay ◽

M. M. Lacey ◽

T. J. Smith ◽

...

Keyword(s):

Escherichia Coli ◽

Silver Nitrate ◽

Biofilm Formation ◽

Galleria Mellonella ◽

Bacterial Colonization ◽

Fibroblast Cell ◽

Cross Resistance ◽

Coating Agent ◽

Content Type

ABSTRACT Uropathogenic Escherichia coli (UPEC) is a frequent cause of catheter-associated urinary tract infection (CAUTI). Biocides have been incorporated into catheter coatings to inhibit bacterial colonization while, ideally, exhibiting low cytotoxicity and mitigating the selection of resistant bacterial populations. We compared the effects of long-term biocide exposure on susceptibility, biofilm formation, and relative pathogenicity in eight UPEC isolates. MICs, minimum bactericidal concentrations (MBCs), minimum biofilm eradication concentrations (MBECs), and antibiotic susceptibilities were determined before and after long-term exposure to triclosan, polyhexamethylene biguanide (PHMB), benzalkonium chloride (BAC), and silver nitrate. Biofilm formation was quantified using a crystal violet assay, and relative pathogenicity was assessed via a Galleria mellonella waxworm model. Cytotoxicity and the resulting biocompatibility index values were determined by use of an L929 murine fibroblast cell line. Biocide exposure resulted in multiple decreases in biocide susceptibility in planktonic and biofilm-associated UPEC. Triclosan exposure induced the largest frequency and magnitude of susceptibility decreases at the MIC, MBC, and MBEC, which correlated with an increase in biofilm biomass in all isolates. Induction of antibiotic cross-resistance occurred in 6/84 possible combinations of bacteria, biocide, and antibiotic. Relative pathogenicity significantly decreased after triclosan exposure (5/8 isolates), increased after silver nitrate exposure (2/8 isolates), and varied between isolates for PHMB and BAC. The biocompatibility index ranked the antiseptic potential as PHMB > triclosan > BAC > silver nitrate. Biocide exposure in UPEC may lead to reductions in biocide and antibiotic susceptibility, changes in biofilm formation, and alterations in relative pathogenicity. These data indicate the multiple consequences of biocide adaptation that should be considered when selecting an anti-infective catheter-coating agent.

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Regulation ofwaaHby PhoB during PiStarvation Promotes Biofilm Formation byEscherichia coliO157:H7

Journal of Bacteriology ◽

10.1128/jb.00093-19 ◽

2019 ◽

Vol 201 (18) ◽

Cited By ~ 1

Author(s):

Philippe Vogeleer ◽

Antony T. Vincent ◽

Samuel M. Chekabab ◽

Steve J. Charette ◽

Alexey Novikov ◽

...

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Ecological Niches ◽

Pho Regulon ◽

Starvation Stress ◽

Content Type ◽

E Coli ◽

Expression Of Genes ◽

K 12 ◽

Pst System

ABSTRACTIn open environments such as water, enterohemorrhagicEscherichia coliO157:H7 responds to inorganic phosphate (Pi) starvation by inducing the Pho regulon controlled by PhoB. This activates the phosphate-specific transport (Pst) system that contains a high-affinity Pitransporter. In the Δpstmutant, PhoB is constitutively activated and regulates the expression of genes in the Pho regulon. Here, we show that Pistarvation and deletion of thepstsystem enhanceE. coliO157:H7 biofilm formation. Among differentially expressed genes of EDL933 grown under Pistarvation conditions and in the Δpstmutant, we have found that a member of the PhoB regulon,waaH, predicted to encode a glycosyltransferase, was highly expressed. Interestingly, WaaH contributed to biofilm formation ofE. coliO157:H7 during both Pistarvation and in the Δpstmutant. In the Δpstmutant, the presence ofwaaHwas associated with lipopolysaccharide (LPS) R3 core type modifications, whereas inE. coliO157:H7,waaHoverexpression had no effect on LPS structure during Pistarvation. Therefore,waaHparticipates inE. coliO157:H7 biofilm formation during Pistarvation, but its biochemical role remains to be clarified. This study highlights the importance of the Pistarvation stress response to biofilm formation, which may contribute to the persistence ofE. coliO157:H7 in the environment.IMPORTANCEEnterohemorrhagicEscherichia coliO157:H7 is a human pathogen that causes bloody diarrhea that can result in renal failure. Outside of mammalian hosts,E. coliO157:H7 survives for extended periods of time in nutrient-poor environments, likely as part of biofilms. InE. coliK-12, the levels of free extracellular Piaffect biofilm formation; however, it was unknown whether Piinfluences biofilm formation byE. coliO157:H7. Our results show that upon Pistarvation, PhoB activateswaaHexpression, which favors biofilm formation byE. coliO157:H7. These findings suggest that WaaH is a target for controlling biofilm formation. Altogether, our work demonstrates how adaptation to Pistarvation allowsE. coliO157:H7 to occupy different ecological niches.

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Conditional Function of Autoaggregative Protein Cah and Common cah Mutations in Shiga Toxin-Producing Escherichia coli

Applied and Environmental Microbiology ◽

10.1128/aem.01739-17 ◽

2017 ◽

Vol 84 (1) ◽

Cited By ~ 3

Author(s):

Michelle Qiu Carter ◽

Maria T. Brandl ◽

Indira T. Kudva ◽

Robab Katani ◽

Matthew R. Moreau ◽

...

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

Calcium Binding ◽

Biofilm Formation ◽

Bacterial Attachment ◽

Ecological Niches ◽

Loss Of Function ◽

Host Colonization ◽

Content Type ◽

E Coli

ABSTRACTCah is a calcium-binding autotransporter protein involved in autoaggregation and biofilm formation. Althoughcahis widespread in Shiga toxin-producingEscherichia coli(STEC), we detected mutations incahat a frequency of 31.3% in this pathogen. In STEC O157:H7 supershedder strain SS17, a large deletion results in a smaller coding sequence, encoding a protein lacking the C-terminal 71 amino acids compared with Cah in STEC O157:H7 strain EDL933. We examined the function of Cah in biofilm formation and host colonization to better understand the selective pressures forcahmutations. EDL933-Cah played a conditional role in biofilm formationin vitro: it enhancedE. coliDH5α biofilm formation on glass surfaces under agitated culture conditions that prevented autoaggregation but inhibited biofilm formation under hydrostatic conditions that facilitated autoaggregation. This function appeared to be strain dependent since Cah-mediated biofilm formation was diminished when an EDL933cahgene was expressed in SS17. Deletion ofcahin EDL933 enhanced bacterial attachment to spinach leaves and altered the adherence pattern of EDL933 to bovine recto-anal junction squamous epithelial (RSE) cells. In contrast, intransexpression of EDL933cahin SS17 increased its attachment to leaf surfaces, and in DH5α, it enhanced its adherence to RSE cells. Hence, the ecological function of Cah appears to be modulated by environmental conditions and other bacterial strain-specific properties. Considering the prevalence ofcahin STEC and its role in attachment and biofilm formation,cahmutations might be selected in ecological niches in which inactivation of Cah would result in an increased fitness in STEC during colonization of plants or animal hosts.IMPORTANCEShiga toxin-producingEscherichia coli(STEC) harbors genes encoding diverse adhesins, and many of these are known to play an important role in bacterial attachment and host colonization. We demonstrated here that the autotransporter protein Cah confers onE. coliDH5α cells a strong autoaggregative phenotype that is inversely correlated with its ability to form biofilms and plays a strain-specific role in plant and animal colonization by STEC. Althoughcahis widespread in the STEC population, we detected a mutation rate of 31.3% incah, which is similar to that reported forrpoSandfimH. The formation of cell aggregates due to increased bacterium-to-bacterium interactions may be disadvantageous to bacterial populations under conditions that favor a planktonic state in STEC. Therefore, a loss-of-function mutation incahis likely a selective trait in STEC when autoaggregative properties become detrimental to bacterial cells and may contribute to the adaptability of STEC to fluctuating environments.

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PBP4 and PBP5 are involved in regulating exopolysaccharide synthesis during Escherichia coli biofilm formation

Microbiology ◽

10.1099/mic.0.001031 ◽

2021 ◽

Vol 167 (3) ◽

Author(s):

Sathi Mallick ◽

Shanti Kiran ◽

Tapas Kumar Maiti ◽

Anindya S. Ghosh

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Type Species ◽

Pentose Phosphate ◽

Bacterial Cells ◽

Surface Adhesion ◽

Content Type ◽

Penicillin Binding Proteins ◽

E Coli ◽

Link Type

Escherichia coli low-molecular-mass (LMM) Penicillin-binding proteins (PBPs) help in hydrolysing the peptidoglycan fragments from their cell wall and recycling them back into the growing peptidoglycan matrix, in addition to their reported involvement in biofilm formation. Biofilms are external slime layers of extra-polymeric substances that sessile bacterial cells secrete to form a habitable niche for themselves. Here, we hypothesize the involvement of Escherichia coli LMM PBPs in regulating the nature of exopolysaccharides (EPS) prevailing in its extra-polymeric substances during biofilm formation. Therefore, this study includes the assessment of physiological characteristics of E. coli CS109 LMM PBP deletion mutants to address biofilm formation abilities, viability and surface adhesion. Finally, EPS from parent CS109 and its ΔPBP4 and ΔPBP5 mutants were purified and analysed for sugars present. Deletions of LMM PBP reduced biofilm formation, bacterial adhesion and their viability in biofilms. Deletions also diminished EPS production by ΔPBP4 and ΔPBP5 mutants, purification of which suggested an increased overall negative charge compared with their parent. Also, EPS analyses from both mutants revealed the appearance of an unusual sugar, xylose, that was absent in CS109. Accordingly, the reason for reduced biofilm formation in LMM PBP mutants may be speculated as the subsequent production of xylitol and a hindrance in the standard flow of the pentose phosphate pathway.

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Novel regulators of the csgD gene encoding the master regulator of biofilm formation in Escherichia coli K-12

Microbiology ◽

10.1099/mic.0.000947 ◽

2020 ◽

Vol 166 (9) ◽

pp. 880-890 ◽

Cited By ~ 1

Author(s):

Hiroshi Ogasawara ◽

Toshiyuki Ishizuka ◽

Shuhei Hotta ◽

Michiko Aoki ◽

Tomohiro Shimada ◽

...

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Cell Aggregation ◽

Master Regulator ◽

Gene Encoding ◽

Content Type ◽

Promoter Probe ◽

K 12 ◽

Specific Environmental Condition

Under stressful conditions, Escherichia coli forms biofilm for survival by sensing a variety of environmental conditions. CsgD, the master regulator of biofilm formation, controls cell aggregation by directly regulating the synthesis of Curli fimbriae. In agreement of its regulatory role, as many as 14 transcription factors (TFs) have so far been identified to participate in regulation of the csgD promoter, each monitoring a specific environmental condition or factor. In order to identify the whole set of TFs involved in this typical multi-factor promoter, we performed in this study ‘promoter-specific transcription-factor’ (PS-TF) screening in vitro using a set of 198 purified TFs (145 TFs with known functions and 53 hitherto uncharacterized TFs). A total of 48 TFs with strong binding to the csgD promoter probe were identified, including 35 known TFs and 13 uncharacterized TFs, referred to as Y-TFs. As an attempt to search for novel regulators, in this study we first analysed a total of seven Y-TFs, including YbiH, YdcI, YhjC, YiaJ, YiaU, YjgJ and YjiR. After analysis of curli fimbriae formation, LacZ-reporter assay, Northern-blot analysis and biofilm formation assay, we identified at least two novel regulators, repressor YiaJ (renamed PlaR) and activator YhjC (renamed RcdB), of the csgD promoter.

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Evaluation of Changes Induced in the Probiotic Escherichia coli M17 Following Recurrent Exposure to Antimicrobials

Journal of Pharmaceutical Research International ◽

10.9734/jpri/2021/v33i29b31601 ◽

2021 ◽

pp. 158-167

Author(s):

M. J. A. Mbarga ◽

I. V. Podoprigora ◽

E. G. Volina ◽

A. V. Ermolaev ◽

L. A. Smolyakova

Keyword(s):

Escherichia Coli ◽

Growth Rate ◽

Silver Nanoparticles ◽

Biofilm Formation ◽

Fold Increase ◽

Bacterial Attachment ◽

Diffusion Method ◽

Cross Resistance ◽

Microdilution Method ◽

Similar Work

Introduction: It is already well known that the exposure of certain bacteria, pathogenic or not, to antimicrobials is likely to increase their virulence and induce the development of direct or cross resistance to antimicrobials, but there is almost no information available regarding probiotics. Aim: To assess the changes induced in susceptibility to antibiotics, biofilm formation, growth rate and relative pathogenicity in the probiotic Escherichia coli M17 (EC-M17) after long exposure to antimicrobials namely ampicillin, kanamycin, cefazolin and silver nanoparticles (AgNPs). Methods: After determining the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the 4 antimicrobials above-mentioned by the microdilution method, EC-M17 was exposed to increasing subinhibitory doses ranging from MIC/8 to MIC for 8 days. The susceptibility to antibiotics of the mutants obtained was assessed by the Kirby Bauer disc diffusion method, biofilm formation by the Congo red agar method and with crystal violet bacterial attachment assay, and relative pathogenicity was assessed using a Galleria melonella waxworm model. Results: Exposure to antimicrobials induces noticeable changes in EC-M17. The highest adaptation to antimicrobials was observed on AgNPs with 8-fold increase in MIC and 16-fold increase in MBC of AgNPs. EC-M17 exposed to ampicillin, kanamycin and silver nanoparticles became resistant to ampicillin, ceftazidime, ceftazidime/clavulanate and tetracycline while exposure to cefazolin induced a significant decrease in sensitivity to tetracycline and ampicillin and resistance to ceftazidime/clavulanate and ceftazidime. The strain exposed to ampicillin was the only one to produce more biofilm than the control strain and except the EC-M17 exposed to cefazolin, all other EC-M17 strains were more pathogenic on G. melonella model than the control. Conclusion: Data in this investigation suggest that repeated exposure of the probiotic EC-M17 to antimicrobials may induce changes in antimicrobials susceptibility, biofilm formation, growth rate, and relative pathogenicity. Therefore, as far as possible, the probiotic E. coli M17 should not be used in combination with antibiotics and further investigations are required to expand similar work on more probiotics in order to avoid resistance build-up which might be transmitted by horizontal transfer.

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Molecular Control of Sucrose Utilization in Escherichia coli W, an Efficient Sucrose-Utilizing Strain

Applied and Environmental Microbiology ◽

10.1128/aem.02544-12 ◽

2012 ◽

Vol 79 (2) ◽

pp. 478-487 ◽

Cited By ~ 53

Author(s):

Suriana Sabri ◽

Lars K. Nielsen ◽

Claudia E. Vickers

Keyword(s):

Escherichia Coli ◽

Growth Rate ◽

Good Growth ◽

Knockout Mutant ◽

Sucrose Transport ◽

Molecular Control ◽

Content Type ◽

E Coli ◽

K 12 ◽

Sucrose Utilization

ABSTRACTSucrose is an industrially important carbon source for microbial fermentation. Sucrose utilization inEscherichia coli, however, is poorly understood, and most industrial strains cannot utilize sucrose. The roles of the chromosomally encoded sucrose catabolism (csc) genes inE. coliW were examined by knockout and overexpression experiments. At low sucrose concentrations, thecscgenes are repressed and cells cannot grow. Removal of either the repressor protein (cscR) or the fructokinase (cscK) gene facilitated derepression. Furthermore, combinatorial knockout ofcscRandcscKconferred an improved growth rate on low sucrose. The invertase (cscA) and sucrose transporter (cscB) genes are essential for sucrose catabolism inE. coliW, demonstrating that no other genes can provide sucrose transport or inversion activities. However,cscKis not essential for sucrose utilization. Fructose is excreted into the medium by thecscK-knockout strain in the presence of high sucrose, whereas at low sucrose (when carbon availability is limiting), fructose is utilized by the cell. Overexpression ofcscA,cscAK, orcscABcould complement the WΔcscRKABknockout mutant or confer growth on a K-12 strain which could not naturally utilize sucrose. However, phenotypic stability and relatively good growth rates were observed in the K-12 strain only when overexpressingcscAB, and full growth rate complementation in WΔcscRKABalso requiredcscAB. Our understanding of sucrose utilization can be used to improveE. coliW and engineer sucrose utilization in strains which do not naturally utilize sucrose, allowing substitution of sucrose for other, less desirable carbon sources in industrial fermentations.

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Influence of Type I Fimbriae and Fluid Shear Stress on Bacterial Behavior and Multicellular Architecture of Early Escherichia coli Biofilms at Single-Cell Resolution

Applied and Environmental Microbiology ◽

10.1128/aem.02343-17 ◽

2018 ◽

Vol 84 (6) ◽

Cited By ~ 8

Author(s):

Liyun Wang ◽

Robert Keatch ◽

Qi Zhao ◽

John A. Wright ◽

Clare E. Bryant ◽

...

Keyword(s):

Escherichia Coli ◽

Shear Stress ◽

Single Cell ◽

Biofilm Formation ◽

Fluid Shear Stress ◽

Cell Membrane Permeability ◽

Type I ◽

Fluid Shear ◽

Content Type ◽

Type I Fimbriae

ABSTRACT Biofilm formation on abiotic surfaces in the food and medical industry can cause severe contamination and infection, yet how biological and physical factors determine the cellular architecture of early biofilms and the bacterial behavior of the constituent cells remains largely unknown. In this study, we examined the specific role of type I fimbriae in nascent stages of biofilm formation and the response of microcolonies to environmental flow shear at the single-cell resolution. The results show that type I fimbriae are not required for reversible adhesion from plankton, but they are critical for the irreversible adhesion of Escherichia coli strain MG1655 cells that form biofilms on polyethylene terephthalate (PET) surfaces. Besides establishing firm cell surface contact, the irreversible adhesion seems necessary to initiate the proliferation of E. coli on the surface. After the application of shear stress, bacterial retention is dominated by the three-dimensional architecture of colonies, independent of the population size, and the multilayered structure could protect the embedded cells from being insulted by fluid shear, while the cell membrane permeability mainly depends on the biofilm population size and the duration of the shear stress. IMPORTANCE Bacterial biofilms could lead to severe contamination problems in medical devices and food processing equipment. However, biofilms are usually studied at a rough macroscopic level; thus, little is known about how individual bacterium behavior within biofilms and the multicellular architecture are influenced by bacterial appendages (e.g., pili/fimbriae) and environmental factors during early biofilm formation. We applied confocal laser scanning microscopy (CLSM) to visualize Escherichia coli microcolonies at a single-cell resolution. Our findings suggest that type I fimbriae are vital to the initiation of bacterial proliferation on surfaces. We also found that the fluid shear stress affects the biofilm architecture and cell membrane permeability of the constituent bacteria in a different way: the onset of the biofilm is linked with the three-dimensional morphology, while membranes are regulated by the overall population of microcolonies.

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Applying the Fama and French three-factor model to analyze risk/reward in the Spanish REITs: an ARDL approach

Journal of European Real Estate Research ◽

10.1108/jerer-11-2019-0043 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Zhenyu Su ◽

Paloma Taltavull

Keyword(s):

Growth Rate ◽

Factor Model ◽

Explanatory Power ◽

Gdp Growth ◽

Size Factor ◽

Content Type ◽

Gdp Growth Rate ◽

Fama And French ◽

Three Factor

Purpose This paper aims to analyse the risk and excess returns of the Spanish real estate investment trusts (S-REITs) using various methods, though focusing primarily on the Fama-French three-factor (FF3) model, over the period from 2007Q3 to 2017Q2. Design/methodology/approach The autoregressive distributed lag model is used for the empirical analysis to test long-term stable relationships between variables. Findings The findings indicate that the FF3 model is suitable for the S-REITs market, better explaining the S-REITs’ returns variation than the traditional single-index capital asset pricing model (CAPM) and the Carhart four-factor model. The empirical evidence is reasonably consistent with the FF3 model; the values for the market, size and value are highly statistically significant over the analysis period, with 68.7% variation in S-REITs’ returns explained by the model. In the long run, the market factor has less explanatory power than the size and value factors; the positive long-term multiplier of the size factor indicates that small S-REIT companies have higher returns, along with higher risk, while the negative multiplier of the value indicator suggests that S-REITs portfolios prefer to allocate growth REITs with low book-to-market ratios. The empirical findings from a modified FF3 model, which additionally incorporates Spain’s gross domestic product (GDP) growth rate, two consumer price index (CPI) macro-factors and three dummy variables, indicates that GDP growth rate and CPI also affect S-REITs’ yields, while investment funds with capital calls have a small influence on S-REITs’ returns. Practical implications The regression results of the standard and extended FF3 model can help researchers understand S-REITs’ risk and return through a general stock pattern. Potential investors are given more information to consider the new Spanish investment vehicle before making a decision. Originality/value The paper uses standard techniques but applies them for the first time to the S-REIT market.

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