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Biofilm formation by Actinobacillus pleuropneumoniae isolates APP286 and APP4294 in microtiter plates after 24 h of incubation. (A) OD 590 nm after crystal violet staining. (B) Confocal laser scanning microscopic image of biofilm of isolate APP286 stained with FilmTracer FM 1-43. Stack of sections through the X-Z plane is shown. ª 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.
Source publication
Actinobacillus pleuropneumoniae causes porcine pleuropneumonia and forms biofilms in vitro on abiotic surfaces; however, presence of biofilms during infections has not been documented. The aim of this study was to use a species-specific fluorescent oligonucleotide probe and confocal microscopy to localize A. pleuropneumoniae in the lungs of two nat...
Contexts in source publication
Context 1
... first evaluated the capacity of these isolates to form biofilms in vitro in a standard microtiter plate assay routinely used in our laboratory. Both isolates formed a robust biofilm on the plastic surface after an incubation of 24 h ( Fig. 2A). These biofilms were then visualized by confocal laser scanning microscopy. The biofilms com- pletely covered the plastic surface and their thickness was evaluated to be around 50 lm (Fig. ...
Context 2
... standard microtiter plate assay routinely used in our laboratory. Both isolates formed a robust biofilm on the plastic surface after an incubation of 24 h ( Fig. 2A). These biofilms were then visualized by confocal laser scanning microscopy. The biofilms com- pletely covered the plastic surface and their thickness was evaluated to be around 50 lm (Fig. ...
Citations
... Biofilms are structured communities of different bacterial cells within a polymeric matrix produced by themselves, which are embedded in a surface, allowing them to survive in the surrounding environment (132). It has been found that App is a bacterium capable of forming biofilms in pigs in natural infection processes (133) and that it can form multispecies biofilms with other porcine respiratory pathogens under laboratory conditions (134). Studies of molecular factors involved in forming biofilms have focused on lipopolysaccharides (LPS) and exopolysaccharides. ...
... Still, there are also important studies concerning the role played by proteins in the adhesion and formation of biofilms. This close relationship between these last two virulence factors could be vital to understanding the pathogenicity of App (133,134). ...
Actinobacillus pleuropneumoniae (App) is a globally distributed Gram-negative bacterium that produces porcine pleuropneumonia. This highly contagious disease produces high morbidity and mortality in the swine industry. However, no effective vaccine exists to prevent it. The infection caused by App provokes characteristic lesions, such as edema, inflammation, hemorrhage, and necrosis, that involve different virulence factors. The colonization and invasion of host surfaces involved structures and proteins such as outer membrane vesicles (OMVs), pili, flagella, adhesins, outer membrane proteins (OMPs), also participates proteases, autotransporters, and lipoproteins. The recent findings on surface structures and proteins described in this review highlight them as potential immunogens for vaccine development.
... In addition to acute infection, A. pleuropneumoniae can persist in the tonsils and lungs of sub-clinically infected pigs, becoming a potential source of disease outbreaks [15,16]. It has been reported that most field isolates of A. pleuropneumoniae can form biofilms [17], and pigs naturally infected with the bacterium can be present as biofilm aggregates in the lungs [18]. A recent study found a negative correlation between the ability of field isolates of A. pleuropneumoniae to form biofilms in vitro and the severity of pig lung pathological injury [17]. ...
... As an important respiratory pathogen, it has been reported that most field isolates of A. pleuropneumoniae form biofilms in the laboratory when initially isolated [17]. In pigs, aggregates of A. pleuropneumoniae in host lungs is considered a biofilm mode of growth, which may act as a reservoir for outbreaks of infection when exposed to stressors or when other pathogens evade the host [18]. Therefore, the biofilm mode of growth can be considered as facilitating survival of A. pleuropneumoniae in the host. ...
Actinobacillus pleuropneumoniae is an important swine respiratory pathogen. Previous studies have suggested that growth as a biofilm is a natural state of A. pleuropneumoniae infection. To understand the survival features involved in the biofilm state, the growth features, morphology and gene expression profiles of planktonic and biofilm A. pleuropneumoniae were compared. A. pleuropneumoniae in biofilms showed reduced viability but maintained the presence of extracellular polymeric substances (EPS) after late log-phase. Under the microscope, bacteria in biofilms formed dense aggregated structures that were connected by abundant EPS, with reduced condensed chromatin. By construction of Δpga and ΔdspB mutants, polymeric β-1,6-linked N-acetylglucosamine and dispersin B were confirmed to be critical for normal biofilm formation. RNA-seq analysis indicated that, compared to their planktonic counterparts, A. pleuropneumoniae in biofilms had an extensively altered transcriptome. Carbohydrate metabolism, energy metabolism and translation were significantly repressed, while fermentation and genes contributing to EPS synthesis and translocation were up-regulated. The regulators Fnr (HlyX) and Fis were found to be up-regulated and their binding motifs were identified in the majority of the differentially expressed genes, suggesting their coordinated global role in regulating biofilm metabolism. By comparing the transcriptome of wild-type biofilm and Δpga, the utilization of oligosaccharides, iron and sulfur and fermentation were found to be important in adhesion and aggregation during biofilm formation. Additionally, when used as inocula, biofilm bacteria showed reduced virulence in mouse, compared with planktonic grown cells. Thus, these results have identified new facets of A. pleuropneumoniae biofilm maintenance and regulation.
Supplementary Information
The online version contains supplementary material available at 10.1186/s13567-023-01173-x.
... The presence of biofilms was indicated by studies of lungs from two naturally infected pigs displaying clinical signs consistent with acute porcine pleuropneumonia [84]. A microscopic examination of the lungs confirmed the clinical diagnosis by displaying typical, multiple foci of coagulation necrosis in the pulmonary parenchyma with microcolonies of small Gram-negative bacilli present. ...
Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment.
... If applied to bacterial cells, the bioassembler stimulates a process of autoaggregation resulting in formation of non-attached bacterial aggregates [52]. Bacterial flocculation and autoaggregation within the liquid volume is a process typical for natural aquatic ecosystems, which is used industrially for waste-water treatments and other applications [72][73][74][75][76]. Non-attached aggregates formed by pathogenic bacteria are described in chronic infections [77][78][79][80]. Formed non-attached aggregates represent 3D multicellular structures that include bacteria and a self-produced matrix. ...
Magnetic force and gravity are two fundamental forces affecting all living organisms, including bacteria. On Earth, experimentally created magnetic force can be used to counterbalance gravity and place living organisms in conditions of magnetic levitation. Under conditions of microgravity, magnetic force becomes the only force that moves bacteria, providing an acceleration towards areas of the lowest magnetic field and locking cells in this area. In this review, we consider basic principles and experimental systems used to create a magnetic force strong enough to balance gravity. Further, we describe how magnetic levitation is applied in on-Earth microbiological studies. Next, we consider bacterial behavior under combined conditions of microgravity and magnetic force onboard a spacecraft. At last, we discuss restrictions on applications of magnetic force in microbiological studies and the impact of these restrictions on biotechnological applications under space and on-Earth conditions.
... Although the ability to form biofilms has been associated with the virulence of AP, it is still not clear how this process contributes in vivo to the pathogenesis of the porcine pleuropneumoniae (Hathroubi et al., 2018). In this respect, the presence of AP aggregates in the lungs of pigs naturally infected has been reported (Tremblay et al., 2017). In addition, it was described the ability of AP to form biofilms on a biotic surface, using a monolayer culture of SJPL cells in which the bacterium formed biofilms at later times (~24h) in comparison with the highest biofilm formation in microplates at 4h. ...
Actinobacillus pleuropneumoniae is a Gram-negative bacterium and the causative agent of porcine pleuropneumonia, a highly contagious disease of pigs characterised by fibrinohaemorrhagic necrotising pneumonia. Although it has been well controlled in some developed countries, outbreaks can occur in pigs of all ages in contact with asymptomatic carriers, leading to significant economic losses to the swine industry due to the high morbidity and mortality rates. Adhesion is a critical step in the colonisation of the swine respiratory tract and the pathogenesis of the porcine pleuropneumonia; however, a literature review of this process is not available to date. Therefore, this review aims to provide information regarding the molecules that have been described in the adhesion of A. pleuropneumoniae to cells and tissues of the porcine respiratory tract. Since adhesion is the first step in biofilm formation, we included a section to describe the genes involved in this process; some of these genes could participate directly or indirectly in the adhesion of A. pleuropneumoniae to the porcine respiratory system. Although the role of biofilms in porcine pleuropneumonia is still not clear, these molecules could be considered in the future as candidates for vaccine development.
... These bacterial aggregates, interestingly, share many of the same characteristics as surface-attached biofilms, such as increased antibiotic resistance/tolerance [13]. Aggregates were also observed in animals such as in the lungs of pigs infected with Actinobacillus pleuropneumoniae [14] and the mammary gland of cows infected with Staphylococcus aureus (I. Doghri, S. Dufour and M. Jacques, unpublished data). ...
Bacterial biofilms are structured clusters of bacterial cells enclosed in a self-produced polymer matrix that are attached to a biotic or abiotic surface. This structure protects bacteria from hostile environmental conditions. There are also accumulating reports about bacterial aggregates associated but not directly adherent to surfaces. Interestingly, these bacterial aggregates exhibit many of the same phenotypes as surface-attached biofilms. Surface-attached biofilms as well as non-attached aggregates are ubiquitous and found in a wide variety of natural and clinical settings. This strongly suggests that biofilm/aggregate formation is important at some steps in the bacterial lifecycle. Biofilm/aggregate formation might therefore be important for some bacterial species for persistence within their host or their environment, while for other bacterial species it might be more important for persistence in the environment between infection of different individuals or even between infection of different hosts (humans or animals). This is strikingly similar to the One Health concept which recognizes that the health and well-being of humans, animals and the environment are intricately linked. We would like to propose that within this One Health concept, the One Biofilm concept also exists, where biofilm/aggregate formation in humans, animals and the environment are also intricately linked. Biofilm/aggregates could represent the unifying factor underneath the One Health concept. The One Biofilm concept would support that biofilm/aggregate formation might be important for persistence during infection but might as well be even more important for persistence in the environment and for transmission between different individuals/different hosts.
... Multi-species interactions are also involved in the persistence of pathogens on inert surfaces (20). Tremblay et al. (22) found that A. pleuropneumoniae can form biofilms in infected pigs, demonstrating for the first time that A. pleuropneumoniae biofilm occurs during the infection process. Our group and, recently, an independent group from China both demonstrated that A. pleuropneumoniae can form multi-species biofilms in combination with other porcine respiratory pathogens, as well as with other bacteria such as Escherichia coli and Staphylococcus aureus under laboratory conditions (23)(24)(25). ...
Actinobacillus pleuropneumoniae is the etiologic agent of porcine contagious pleuropneumonia, an important respiratory disease for the pig industry. A. pleuropneumoniae has traditionally been considered an obligate pig pathogen. However, its presence in the environment is starting to be known. Here, we report the A. pleuropneumoniae surviving in biofilms in samples of drinking water of swine farms from Mexico. Fourteen farms were studied. Twenty drinking water samples were positive to A. pleuropneumoniae distributed on three different farms. The bacteria in the drinking water samples showed the ability to form biofilms in vitro. Likewise, A. pleuropneumoniae biofilm formation in situ was observed on farm drinkers, where the biofilm formation was in the presence of other bacteria such as Escherichia coli, Stenotrophomonas maltophilia, and Acinetobacter schindleri. Our data suggest that A. pleuropneumoniae can inhabit aquatic environments using multi-species biofilms as a strategy to survive outside of their host.
... The matrix is important for cell-to-cell cohesion and attachment to surfaces. However, bacterial biofilms and aggregates formed in vivo are not necessarily attached to a surface and are often embedded in host-derived material [3][4][5]. This highlights the ability of bacteria to adapt to different microniches, including those found in humans and animals. ...
... Several Gramnegative and Gram-positive pathogens of veterinary importance can form biofilms and are found in cattle, sheep, pigs, chickens, and turkeys [32]. For example, the etiological agent of porcine pleuropneumonia, A. pleuropneumoniae, forms biofilm aggregates in lungs during a natural infection [5]. Other swine respiratory pathogens may form similar structures during infections [32,33]. ...
Introduction
Microorganisms can develop into a social organization known as biofilms and these communities can be found in virtually all types of environment on earth. In biofilms, cells grow as multicellular communities held together by a self-produced extracellular matrix. Living within a biofilm allows for the emergence of specific properties for these cells that their planktonic counterparts do not have. Furthermore, biofilms are the cause of several infectious diseases and are frequently inhabited by multi-species. These interactions between microbial species are often critical for the biofilm process. Despite the importance of biofilms in disease, vaccine antigens are typically prepared from bacteria grown as planktonic cells under laboratory conditions. Vaccines based on planktonic bacteria may not provide optimal protection against biofilm-driven infections.
Areas covered
In this review, we will present an overview of biofilm formation, what controls this mode of growth, and recent vaccine development targeting biofilms.
Expert opinion
Previous and on-going research provides evidence that vaccine formulation with antigens derived from biofilms is a promising approach to prevent infectious diseases and can enhance the protective efficacy of existing vaccines. Therefore, research focusing on the identification of biofilm-derived antigens merits further investigations.
... Several studies have demonstrated that A. pleuropneumoniae can produce a biofilm (Kaplan & Mulks, 2005;Kaplan et al., 2004;Labrie et al., 2002), although, like fimbrial production, the ability to produce a biofilm can be lost during sub-culture in vitro (Kaplan & Mulks, 2005). In vivo, A. pleuropneumoniae forms aggregates in pig lungs that are structurally distinct from the biofilms formed in vitro (Tremblay, Labrie, Chenier, & Jacques, 2017), leading to the proposal that a refinement of in vitro biofilm assays by using a porous substrate (agarose) which favored the formation of aggregates is necessary to better reflect in vivo conditions where biofilms are formed. ...
Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is responsible for high economic losses in swine herds across the globe. Pleuropneumonia is characterized by severe respiratory distress and high mortality. The knowledge about the interaction between bacterium and host within the porcine respiratory tract has improved significantly in recent years. A. pleuropneumoniae expresses multiple virulence factors, which are required for colonization, immune clearance, and tissue damage. Although vaccines are used to protect swine herds against A. pleuropneumoniae infection, they do not offer complete coverage, and often only protect against the serovar, or serovars, used to prepare the vaccine. This review will summarize the role of individual A. pleuropneumoniae virulence factors that are required during key stages of pathogenesis and disease progression, and highlight progress made toward developing effective and broadly protective vaccines against an organism of great importance to global agriculture and food production.
... Several studies have demonstrated that A. pleuropneumoniae can produce a biofilm (Kaplan & Mulks, 2005;Kaplan et al., 2004;Labrie et al., 2002), although, like fimbrial production, the ability to produce a biofilm can be lost during sub-culture in vitro (Kaplan & Mulks, 2005). In vivo, A. pleuropneumoniae forms aggregates in pig lungs that are structurally distinct from the biofilms formed in vitro (Tremblay, Labrie, Chenier, & Jacques, 2017), leading to the proposal that a refinement of in vitro biofilm assays by using a porous substrate (agarose) which favored the formation of aggregates is necessary to better reflect in vivo conditions where biofilms are formed. ...
Ac.ti.no.ba.cil'lus. Gr. fem. n. actis a ray; L. dim. masc. n. bacillus a small staff or rod; N.L. masc. n. Actinobacillus ray bacillus or rod.
Proteobacteria / Gammaproteobacteria / Pasteurellales / Pasteurellaceae / Actinobacillus
Actinobacillus is a genus within the family Pasteurellaceae. The sensu stricto definition of the genus Actinobacillus has been adopted for this Manual, meaning the genus comprises 10 species – Actinobacillus anseriformium, Actinobacillus arthritidis, Actinobacillus capsulatus, Actinobacillus equuli, Actinobacillus hominis, Actinobacillus lignieresii, Actinobacillus pleuropneumoniae, Actinobacillus suis, Actinobacillus ureae, and Actinobacillus vicugnae. Members of the genus Actinobacillus are Gram‐negative, facultatively anaerobic, and nonmotile cells that are coccoidal or rod shaped. Most often bacillary but sometimes interspersed with coccal elements that may lie at the pole of a larger form, producing the characteristic “Morse‐code” form. Cell forms up to 6 μm in length may appear when grown on media containing glucose or maltose. Cells are single or arranged in pairs or, more rarely, in chains. Endospores are not formed. Members of the genus are not acid fast. Isolates can have both respiratory and fermentative types of metabolism. After growth for 24 h on blood agar, translucent colonies, usually 1–2 mm in diameter, appear. Surface colonies have low viability and may die in 2–7 days. Growth may be very sticky upon primary cultivation, making it difficult to remove colonies completely from the agar surface. The optimum growth temperature is 37°C. The temperature range for growth is 25–42°C. Several species are regarded as primary pathogens of animals, while the remaining species are typically normal flora of the mucosal surfaces of the respiratory or genital tract of humans or animals with some potential to play a secondary role in disease processes under some conditions.
DNA G + C content (mol%): 39.9–41.3 (WGS).
Type species: Actinobacillus lignieresii Brumpt 1910AL.
