Antifungal Bacteria Research Articles

Molecular Identification of Four Antifungal Bacteria from Potato (Solanum tuberosum) and Strawberry (Fragaria x ananassa) Plants and their Rhizosphere Soils

Molecular Identification of Four Antifungal Bacteria from Potato (Solanum tuberosum) and Strawberry (Fragaria x ananassa) Plants and their Rhizosphere Soils

Isolation and study of plant growth promoting rhizobacteria from Triticosecale Wittmack growing in Almaty region

This article presents data on isolation and characterization of native plant growth-promoting rhizobacteria (PGPR) from the rhizosphere and root-endosphere of X Triticosecale Wittmack growing in Almaty region. A total of 22 distinct (eighteen gram-negative and four gram-positive) bacterial isolates were identified, classified according to their spore-forming activity: eighteen non-spore-forming and four spore-forming bacteria. Bacterial isolates were screened in vitro for PGPR characteristics and evaluated for their beneficial effects on the early growth of triticale variety X Triticosecale Wittmack. The findings of our research indicated isolation of four growth-promoting bacteria (AS4, AS6, AR1, TS6), three antifungal bacteria (AR2 and AS7), and one strain of combined action, i.e. high growth-promoting and fungistatic activity (AR6). Research has demonstrated that PGPR can be utilized as biofertilizers for crop production. Study marks the beginning of a larger investigation into the bacterial diversity of the triticale variety X Triticosecale Wittmack in the Almaty region.

Environmental factors and host sex influence the skin microbiota structure of Hong Kong newt (Paramesotriton hongkongensis) in a coldspot of chytridiomycosis in subtropical East Asia.

Chytridiomycosis, an infectious skin disease caused by the chytrid fungi, Batrachochytrium dendrobatidis and B. salamandrivorans, poses a significant threat to amphibian biodiversity worldwide. Antifungal bacteria found on the skin of chytrid-resistant amphibians could potentially provide defense against chytridiomycosis and lower mortality rates among resistant individuals. The Hong Kong newt (Paramesotriton hongkongensis) is native to East Asia, a region suspected to be the origin of chytrids, and has exhibited asymptomatic infection, suggesting a long-term coexistence with the chytrids. Therefore, the skin microbiota of this resistant species warrant investigation, along with other factors that can affect the microbiota. Among the 149 newts sampled in their natural habitats in Hong Kong, China, putative antifungal bacteria were found in all individuals. There were 314 amplicon sequence variants distributed over 25 genera of putative antifungal bacteria; abundant ones included Acinetobacter, Flavobacterium, and Novosphingobium spp. The skin microbiota compositions were strongly influenced by the inter-site geographical distances. Despite inter-site differences, we identified some core skin microbes across sites that could be vital to P. hongkongensis. The dominant cores included the family Comamonadaceae, family Chitinophagaceae, and class Betaproteobacteria. Moreover, habitat elevation and host sex also exhibited significant effects on skin microbiota compositions. The antifungal bacteria found on these newts offer an important resource for conservation against chytridiomycosis, such as developing probiotic treatments for susceptible species.

Facile green fabrication of magnetite nanoparticles using an aqueous flower extract of Murraya paniculata (L) Jack for an efficient removal of organic dye pollutant, antibacterial activities

This article reports, the plant-mediated synthesis of Magnetite nanoparticles achieved by utilising an aqueous flower extract of Murraya paniculata (L) Jack (FMPM NPs). The active compounds are phenols, alkaloids, flavones and terpenoids in the aqueous flower extract of Murraya paniculata act as ligating agents to synthesize novel green superparamagnetic magnetite nanoparticles by the coprecipitation method. As prepared FMPM NPs have been characterized by a range of spectroscopic and microscopic techniques. All spectroscopic and microscopic results confirmed the occurrence of pure FMPM NPs. Fourier transform-infrared spectroscopy (FTIR) shows the presence of a Fe-O bond and the band gap was found to be 2.57 eV for FMPM NPs. The surface area of the synthesized nanoparticles was 70.31 m2/g evaluated by BET analysis. The elemental analysis has been performed by the XPS technique. The XRD pattern revealed the crystal size of 14.12 nm of FMPM NPs. TEM images show the spherical shaped FMPM NPs with an average particle size of 11.58 nm. SEM results clearly show spherically shaped FMPM NPs. The superparamagnetic character of FMPM NPs is revealed by the VSM curve and saturation magnetization (Ms) value of 58 emu/g. FMPM NPs used for photocatalytic activity, tested against gram positive, gram negative and antifungal bacteria. As prepared FMPM NPs. showed 93 % removal efficiency of Fast sulphon black-F dye pollutant. Moreover, FMPM NPs efficiently inhibit the growth of Enterococcus faecalis and Penicillium chrysogenum. The current research is for the fabrication of magnetite nanoparticles utilising novel green source and examining their applications.

From phyllosphere to insect cuticles: silkworms gather antifungal bacteria from mulberry leaves to battle fungal parasite attacks

BackgroundBacterial transfers from plants to insect herbivore guts have been well investigated. However, bacterial exchanges between plant phyllospheres and insect cuticles remain unclear, as does their related biological function.ResultsHere, we report that the cuticular bacterial loads of silkworm larvae quickly increased after molting and feeding on the white mulberry (Morus alba) leaves. The isolation and examination of silkworm cuticular bacteria identified one bacterium Mammaliicoccus sciuri that could completely inhibit the spore germination of fungal entomopathogens Metarhizium robertsii and Beauveria bassiana. Interestingly, Ma. sciuri was evident originally from mulberry leaves, which could produce a secreted chitinolytic lysozyme (termed Msp1) to damage fungal cell walls. In consistency, the deletion of Msp1 substantially impaired bacterial antifungal activity. Pretreating silkworm larvae with Ma. sciuri cells followed by fungal topical infections revealed that this bacterium could help defend silkworms against fungal infections. Unsurprisingly, the protective efficacy of ΔMsp1 was considerably reduced when compared with that of wild-type bacterium. Administration of bacterium-treated diets had no negative effect on silkworm development; instead, bacterial supplementation could protect the artificial diet from Aspergillus contamination.ConclusionsThe results of this study evidence that the cross-kingdom transfer of bacteria from plant phyllospheres to insect herbivore cuticles can help protect insects against fungal parasite attacks.2Gz4BRurS3WWiYBnkN9F_dVideo

Hair cosmetic ingredients from the symbiont bacteria Xylocarpus sp. fruit are based on antimicrobial and antifungal bacteria

The symbiotic bacteria of the mangrove fruit, Xylocarpus sp., have the potential to act as antibacterial and antifungal agents. The research objective is to determine the possibility of producing symbiotic bacteria for the cosmetic bioindustry. Isolate Alcaligenes aquatilis (Isolate X1.63), Sinomicrobium oceani (Isolate X2.52), S. oceani (Isolate X1.54), Pseudomonas khazarica (Isolate X1.64), S. oceani (Isolate X1.53), and Proteus mirabilis (Isolate X1.65) bacteria were used as samples and tested against pathogenic bacteria and pathogenic fungi. Then, a cream was prepared using symbiotic bacteria as the main ingredient with different concentrations for subsequent testing on mouse skin over 14 days. Finally, it was analyzed using histological methods. Hair follicle growth ability was observed at various concentrations of the cream. Specifically, the consortium bacterial cream shows superior efficacy compared to other treatments. Testing bacterial extract as a cream formulation can be an alternative treatment for alopecia (baldness). The research findings concluded that the symbiotic bacteria of Xylocarpus sp. mangrove fruit have the potential to be used as a material for the cosmetic bioindustry. This is because, in addition to having antibacterial and antifungal properties, they also demonstrate potential for use as a hair cream product for treating alopecia.

Bacillus subtilis engineered for topical delivery of an antifungal agent.

Fungal skin infections are a common condition affecting 20-25 percent of the world population. While these conditions are treatable with regular application of an antifungal medication, we sought to develop a more convenient, longer-lasting topical antifungal platform that could increase patient adherence to treatment regimens by using Bacillus subtilis, a naturally antifungal bacteria found on the skin, for drug production and delivery. In this study, we engineered B. subtilis for increased production of the antifungal lipopeptide iturin A by overexpression of the pleiotropic regulator DegQ. The engineered strain had an over 200% increase in iturin A production as detected by HPLC, accompanied by slower growth but the same terminal cell density as determined by absorbance measurements of liquid culture. In an in vitro antifungal assay, we found that despite its higher iturin A production, the engineered strain was less effective at reducing the growth of a plug of the pathogenic fungus Trichophyton mentagrophytes on an agar plate compared to the parent strain. The reduced efficacy of the engineered strain may be explained by its reduced growth rate, which highlights the need to address trade-offs between titers (e.g. measured drug production) and other figures of merit (e.g. growth rate) during metabolic engineering.

Metabolites of Mangrove Sediment Bacteria from Semarang and Karimunjawa as Anti-Fungal and Antibacterial

Pathogenic bacteria are microorganisms that cause disease in humans because bacteria grow cosmopolitan with human life, both on land and underwater. This research aimed to obtain mangrove sediment bacteria that have the potential as antibacterial and antifungal bacteria from mangrove sediments in Semarang and Karimunjawa waters. Mangrove sediment bacteria that have the potential as antibacterial and antifungal bacteria from Semarang and Karimunjawa waters, as well as identification of their compounds using the GCMS method. Sediment samples were collected from Semarang and Karimunjawa, and bacterial screening and isolation were then carried out. Bacterial isolates were tested with pathogenic fungi Malassezia furfur and Candida albicans. As well as the pathogenic bacteria Staphylococcus aureus, Escherichia coli, and Staphylococcus typhi. Then, the potential bacteria were identified by the molecular DNA method and analyzed by the GC-MS method to determine the secondary metabolite compounds that act as antifungal and antibacterial. The results showed that the bacterial isolation of mangrove sediments from Karimunjawa and Semarang that had antibacterial activity against pathogenic bacteria E. coli, S. aureus, and S. typhi were 3 isolates, namely SKK 1 MA, SKS 2 ISP, and SKS 4 ISP. The 3 isolates also had antifungal activity against the fungal pathogens Malassezia furfur and Candida albicans. The molecular identification showed that the 3 potential isolates, namely SKK 1 MA, SKS 2 ISP, and SKS 4 ISP, were Bacillus sp., Bacillus cereus, and Alcaligenes faecalis, respectively. Results of the analysis of the content of bacteria as antifungal and antibacterial showed that the bacteria were dominated by the content of unsaturated fatty acids (omega 9) and saturated fatty acids. HIGHLIGHTS Pathogenic fungal infections are difficult to treat besides infections caused by pathogenic bacteria Natural substances produced by microorganisms are very diverse in structure and are an essential source in the search for new drugs for various diseases in humans, including infections by pathogenic fungi and pathogenic bacteria The mangrove sediment bacteria were found to have potential as antifungal and antibacterial and were proven to contain fatty acids Bacteria found to be useful as antifungal and antibacterial agents for various bio-industrial activities GRAPHICAL ABSTRACT

The Wsp chemosensory system modulates c-di-GMP-dependent biofilm formation by integrating DSF quorum sensing through the WspR-RpfG complex in Lysobacter

The ubiquitous Wsp (wrinkly spreader phenotype) chemosensory system and DSF (diffusible signal factor) quorum sensing are two important chemically associated signaling systems that mediate bacterial communications between the host and environment. Although these two systems individually control biofilm formation in pathogenic bacteria via the ubiquitous second messenger c-di-GMP, their crosstalk mechanisms remain elusive. Here we present a scenario from the plant-beneficial and antifungal bacterium Lysobacter enzymogenes OH11, where biofilm formation favors the colonization of this bacterium in fungal hyphae. We found that the Wsp system regulated biofilm formation via WspR-mediated c-di-GMP signaling, whereas DSF system did not depend on the enzymatic activity of RpfG to regulate biofilm formation. We further found that WspR, a diguanylate cyclase (DGC) responsible for c-di-GMP synthesis, could directly bind to one of the DSF signaling components, RpfG, an active phosphodiesterase (PDE) responsible for c-di-GMP degradation. Thus, the WspR-RpfG complex represents a previously undiscovered molecular linker connecting the Wsp and DSF systems. Mechanistically, RpfG could function as an adaptor protein to bind and inhibit the DGC activity of unphosphorylated WspR independent of its PDE activity. Phosphorylation of WspR impaired its binding affinity to RpfG and also blocked the ability of RpfG to act as an adaptor protein, which enabled the Wsp system to regulate biofilm formation in a c-di-GMP-dependent manner by dynamically integrating the DSF system. Our findings demonstrated a previously uncharacterized mechanism of crosstalk between Wsp and DSF systems in plant-beneficial and antifungal bacteria.

Life stage and proximity to roads shape the skin microbiota of eastern newts (Notophthalmus viridescens).

Host-associated microbiomes play an essential role in the health of organisms, including immune system activation, metabolism and energy uptake. It is well established that microbial communities differ depending on the life stage and natural history of the organism. However, the effects of life stage and natural history on microbial communities may also be influenced by human activities. We investigated the effects of amphibian life stage (terrestrial eft vs. aquatic adult) and proximity to roadways on newt skin bacterial communities. We found that the eft and adult life stages differed in bacterial community composition; however, the effects of roads on community composition were more evident in the terrestrial eft stage compared to the aquatic adult stage. Terrestrial efts sampled close to roads possessed richer communities than those living further away from the influence of roads. When accounting for amplicon sequence variants with predicted antifungal capabilities, in the adult life stage, we observed a decrease in anti-fungal bacteria with distance to roads. In contrast, in the eft stage, we found an increase in anti-fungal bacteria with distance to roads. Our results highlight the need to consider the effects of human activities when evaluating how host-associated microbiomes differ across life stages of wildlife.

Occidiofungin Is the Key Metabolite for Antifungal Activity of the Endophytic Bacterium Burkholderia sp. MS455 Against Aspergillus flavus.

Aflatoxin is a secondary metabolite produced by Aspergillus fungi and presents a major food safety concern globally. Among the available methods for prevention and control of aflatoxin, the application of antifungal bacteria has gained favor in recent years. An endophytic bacterium MS455, isolated from soybean, exhibited broad-spectrum antifungal activity against economically important pathogens, including Aspergillus flavus. MS455 was identified as a strain of Burkholderia based on genomic analysis. Random and site-specific mutations were used in discovery of the genes that share high homology to the ocf gene cluster of Burkholderia contaminans strain MS14, which is responsible for production of the antifungal compound occidiofungin. RNA sequencing analysis demonstrated that ORF1, a homolog to the ambR1 LuxR-type regulatory gene, regulates occidiofungin biosynthesis in MS455. Additionally, 284 differentially expressed genes, including 138 upregulated and 146 downregulated genes, suggesting that, in addition to its role in occidiofungin production, ORF1 is involved in expression of multiple genes, especially those involved in ornibactin biosynthesis. Plate bioassays showed the growth of A. flavus was significantly inhibited by the wild-type strain MS455 as compared with the ORF1 mutant. Similarly, corn kernel assays showed that growth of A. flavus and aflatoxin production were reduced significantly by MS455 as compared with buffer control and the ORF1 mutant. Collectively, the results demonstrated that production of occidiofungin is essential for antifungal activity of the endophytic bacterium MS455. This research has provided insights about antifungal mechanisms of MS455 and development of biological approaches to prevent aflatoxin contamination in plant production.

Isolation and Identification of Antifungal Bacteria from Rhizosphere of Citrus Field

Isolation and Identification of Antifungal Bacteria from Rhizosphere of Citrus Field

Antifungal strains and gene mapping of secondary metabolites in mangrove sediments from Semarang city and Karimunjawa islands, Indonesia.

Infection caused by pathogenic fungal species is one of the most challenging disease to be tackled today. The antifungal bacteria candidate can be found in terrestrial as well as aquatic ecosystems, with mangrove forests being one of them. The purpose of this study is to obtain candidate isolates of antifungal strains with a detection approach and gene mapping simulation of bioactive compounds producers and screening to determine qualitative antifungal activity. The research will be carried out by collecting sediment samples from the mangrove ecosystems of Karimunjawa and Mangkang sub-district of Semarang city, isolating and purifying bacteria with Humic Acid Vitamin Agar (HVA), International Streptomyces Project 1 (ISP 1) and Zobell (Marine Agar). added with antibiotics, qualitative antifungal ability screening of each isolate obtained, detection of the presence of PKS gene and NRPS using special primers using the Polymerase Chain Reaction (PCR) method, and molecular identification of each isolate by 16s rRNA sequencing method. Of the total 59 isolates produced from the sample isolation process, 31 isolates from Karimunjawa sediments and 8 isolates from Semarang sediments showed activity against test pathogenic bacteria, namely Candida albicans, Trichoderma sp., and Aspergillus niger. Detection of Biosynthethic Gene Cluster (BGC) showed that the genes encoding secondary metabolites (NRPS, PKS 1 and PKS 2) were detected in KI 2-2 isolates from Karimunjawa. NRPS were detected only in isolates SP 3-9, SH 3-4, KI 1-6, KI 2-2, KI 2-4. The secondary metabolite-encoding gene, PKS1, was detected in isolates SP 3-5, SP 3-8, KI 2-2. PKS II genes were detected only on isolates SP 2-4, SH 3-8, KI 1-6, KI 2-2, and KI 2-4. Isolate SP 3-5 was revealed as Pseudomonas aeruginosa (93.14%), isolate SP 2-4 was Zhouia amylolytica strain HN-181 (100%) and isolate SP 3-8 was P. aeruginosa strain QK -2 (100%).

Isolation of Burkholderia sp. HQB-1, A Promising Biocontrol Bacteria to Protect Banana Against Fusarium Wilt Through Phenazine-1-Carboxylic Acid Secretion.

Fusarium wilt is a devastating soil-borne fungal disease caused by Fusarium oxysporum f.sp. cubense (Foc). In recent years, some antifungal bacteria have been applied for the prevention and biocontrol of pathogenic fungi. In our study, a bacterial strain HQB-1, isolated from banana rhizosphere soil, was cultured for investigation. It showed broad-spectrum antifungal activities against representative phytopathogenic fungi including Fusarium oxysporum, Colletotrichum gloeosporioides, Botrytis cinerea, and Curvularia fallax. The strain HQB-1 was identified as Burkholderia sp. by morphological, physiological, and biochemical examinations, confirmed by 16S rRNA gene sequence analysis. Among the metabolites produced by the strain, we identified an antifungal compound which was identified phenazine-1-carboxylic acid (PCA) (C13H8N2O2) through ultraviolet, liquid chromatography quadrupole-time of flight mass spectrometer, and nuclear magnetic response. Furthermore, PCA exhibited the lowest minimum inhibitory concentration (MIC) against F. oxysporum (1.56 μg/ml) and yielded the highest MIC against C. gloeosporioides. Pot experiments showed that application of 5 μg/ml or more of PCA efficiently controlled banana wilt and promoted the growth of banana plants. These results suggested that Burkholderia sp. HQB-1, as an important microbial resource of PCA, could be a promising biological agent against wilt diseases and promoting banana growth.

Prospecting for antifungal molecules

Antifungal Discovery Marine bacteria produce a plethora of natural products that often have unusual chemical structures and corresponding reactivity, which sometimes translate into a valuable biological function. Zhang et al. used a metabolomic screen to zero in on microbial strains from the microbiome of a sea squirt that produces a high diversity of chemical structures. They then screened these molecules for inhibition of fungi (see the Perspective by Cowen). A polycyclic molecule dubbed turbinmicin possessed potent antifungal activity against the multidrug-resistant fungal pathogens Candida auris and Aspergillus fumigatus . Preliminary mechanism-of-action and mouse toxicity studies suggest that this molecule works though a fungus-specific pathway and is well tolerated at therapeutic doses. Science , this issue p. [974][1]; see also p. [906][2] [1]: /lookup/doi/10.1126/science.abd6919 [2]: /lookup/doi/10.1126/science.abf1675

Microbiological Assessments in a Cut Flower Crop Polytunnel Field Trial Adopting Soil Covering and Microbiocides for Fusarium Wilt Suppression

Cut flower Matthiola incana were raised by local commercial cultivators in a polytunnel. The field soil beds were either left uncovered as normal or covered with polythene sheets (except a hole for plant plug space). Average temperatures in the top 5 cm soil under cover dropped from 28 oC to 18 oC compared to its spiking up to 37 oC in uncovered counterparts. Microbiological analyses indicated that soil covering induced two log10 folds reduction of the wilt causal fungi Fusarium oxysporum and concomitantly increased one log10 fold wilt antagonistic natural soil inhabiting fungi populations. Standard dip/drench mixtures of commercial and local isolates microbiocides (bacteria) applied to M. incana plug roots improved plant health assessed by visible scores of the level of damage or wilt symptoms under soil covered treatments. Scanning electron microscopy, cultural and 16S rRNA PCR analyses revealed potent antifungal bacteria attached to the hyphal surfaces of F. oxysporum as ectosymbionts that may have implications for virulence regulation and host plants’ wilt disease control. Our microbiological data support the prospects of combining physiological and microbiological interventions upon covering the soil surface that offers the local horticulturists an evidence based sustainable means of Fusarium wilt control suppression in polytunnel crops.

The Amphibian Skin Microbiome and Its Protective Role Against Chytridiomycosis

Here we review the knowledge about skin microbiomes in amphibians accumulated over the last two decades and the evidence regarding the protective role of skin bacteria. Amphibians all over the world are declining because of several factors, including chytridiomycosis disease caused by the fungal pathogens Batrachochytrium dendrobatidis and B. salamandrivorans. In this context, the antifungal capacities of many bacteria living symbiotically on amphibian skin, which have been described both in vitro and in vivo, are important in disease prevention. We discuss the major factors influencing amphibian skin bacterial communities, the fungal component of the amphibian skin microbiome, and the potential use of antifungal bacteria as probiotics. The structure of amphibian skin microbial communities is influenced by host-specific microhabitat, biogeographic, and climatic factors, but the functional aspects of these microbiomes and how these nested factors modulate skin microbial functions remains largely unexplored. However, the field has grown considerably, and recent technologies have prompted the exploration of exciting new questions aimed at providing more detailed knowledge about the ecology of amphibian–microbial symbioses and the precise role of the skin microbiome in protecting host amphibians against emerging diseases.

The cutaneous microbiota of bats has in vitro antifungal activity against the white nose pathogen.

Since its introduction into the USA, Pseudogymnoascus destructans (Pd), the fungal pathogen of white-nose syndrome, has killed millions of bats. Recently, bacteria capable of inhibiting the growth of Pd have been identified within bat microbial assemblages, leading to increased interest in elucidating bacterial assemblage-pathogen interactions. Our objectives were to determine if bat cutaneous bacteria have antifungal activity against Pd, and correlate differences in the bat cutaneous microbiota with the presence/absence of Pd. We hypothesized that the cutaneous microbiota of bats is enriched with antifungal bacteria, and that the skin assemblage will correlate with Pd status. To test this, we sampled bat microbiota, adjacent roost surfaces and soil from Pd positive caves to infer possible overlap of antifungal taxa, we tested these bacteria for bioactivity in vitro, and lastly compared bacterial assemblages using both amplicon and shotgun high-throughput DNA sequencing. Results suggest that the presence of Pd has an inconsistent influence on the bat cutaneous microbial assemblage across sites. Operational taxonomic units (OTUs) that corresponded with cultured antifungal bacteria were present within all sample types but were significantly more abundant on bat skin relative to the environment. Additionally, the microbial assemblage of Pd negative bats was found to have more OTUs that corresponded to antifungal taxa than positive bats, suggesting an interaction between the fungal pathogen and cutaneous microbial assemblage.

Probiotics Modulate a Novel Amphibian Skin Defense Peptide That Is Antifungal and Facilitates Growth of Antifungal Bacteria.

Probiotics can ameliorate diseases of humans and wildlife, but the mechanisms remain unclear. Host responses to interventions that change their microbiota are largely uncharacterized. We applied a consortium of four natural antifungal bacteria to the skin of endangered Sierra Nevada yellow-legged frogs, Rana sierrae, before experimental exposure to the pathogenic fungus Batrachochytrium dendrobatidis (Bd). The probiotic microbes did not persist, nor did they protect hosts, and skin peptide sampling indicated immune modulation. We characterized a novel skin defense peptide brevinin-1Ma (FLPILAGLAANLVPKLICSITKKC) that was downregulated by the probiotic treatment. Brevinin-1Ma was tested against a range of amphibian skin cultures and found to inhibit growth of fungal pathogens Bd and B. salamandrivorans, but enhanced the growth of probiotic bacteria including Janthinobacterium lividum, Chryseobacterium ureilyticum, Serratia grimesii, and Pseudomonas sp. While commonly thought of as antimicrobial peptides, here brevinin-1Ma showed promicrobial function, facilitating microbial growth. Thus, skin exposure to probiotic bacterial cultures induced a shift in skin defense peptide profiles that appeared to act as an immune response functioning to regulate the microbiome. In addition to direct microbial antagonism, probiotic-host interactions may be a critical mechanism affecting disease resistance.

Integrating the role of antifungal bacteria into skin symbiotic communities of three Neotropical frog species.

Chytridiomycosis, caused by the pathogen Batrachochytrium dendrobatidis (Bd), has led to population declines and extinctions of frog species around the world. While it is known that symbiotic skin bacteria can play a protective role against pathogens, it is not known how these defensive bacteria are integrated into the bacterial community on amphibian skin. In this study, we used 16S rRNA gene amplicon sequencing, culturing and Bd inhibition bioassays to characterize the communities of skin bacteria on three Neotropical frog species that persist in a Bd-infected area in Panama and determined the abundance and integration of anti-Bd bacteria into the community. We found that the two treefrog species had a similar bacterial community structure, which differed from the more diverse community found on the terrestrial frog. Co-occurrence networks also revealed differences between frog species such that the treefrogs had a significantly higher number of culturable Bd-inhibitory OTUs with high centrality scores compared with the terrestrial frog. We found that culture-dependent OTUs captured between 21 and 39% of the total relative abundance revealed in culture-independent communities. Our results suggest different ecological strategies occurring within skin antifungal communities on host species that have not succumbed to Bd infections in the wild.