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Uncovering the cultivable microbial diversity of costa rican beetles and its ability to break down plant cell wall components.

Vargas-Asensio G, Pinto-Tomas A, Rivera B, Hernandez M, Hernandez C, Soto-Montero S, Murillo C, Sherman DH, Tamayo-Castillo G - PLoS ONE (2014)

Bottom Line: We isolated and described the cultivable fungi, actinomycetes and aerobic eubacteria associated with the gut of larvae and adults from six different beetle families colonizing decomposing logs in protected Costa Rican ecosystems.Highest scores in these assays were achieved by a fungal isolate (Anthostomella sp.), two Streptomyces and one Bacillus bacterial isolates.Our study demonstrates that Costa Rican beetles harbor several types of cultivable microbes, some of which may be involved in symbiotic relationships that enable the insect to digest complex polymers such as lignocellulose.

View Article: PubMed Central - PubMed

Affiliation: Instituto Nacional de Biodiversidad (INBio), Santo Domingo de Heredia, Costa Rica; Departamento de Bioquímica, Universidad de Costa Rica, San Pedro de Montes de Oca, Costa Rica.

ABSTRACT
Coleopterans are the most diverse insect order described to date. These organisms have acquired an array of survival mechanisms through their evolution, including highly efficient digestive systems. Therefore, the coleopteran intestinal microbiota constitutes an important source of novel plant cell wall-degrading enzymes with potential biotechnological applications. We isolated and described the cultivable fungi, actinomycetes and aerobic eubacteria associated with the gut of larvae and adults from six different beetle families colonizing decomposing logs in protected Costa Rican ecosystems. We obtained 611 isolates and performed phylogenetic analyses using the ITS region (fungi) and 16S rDNA (bacteria). The majority of fungal isolates belonged to the order Hypocreales (26% of 169 total), while the majority of actinomycetes belonged to the genus Streptomyces (86% of 241 total). Finally, we isolated 201 bacteria spanning 19 different families belonging into four phyla: Firmicutes, α, β and γ-proteobacteria. Subsequently, we focused on microbes isolated from Passalid beetles to test their ability to degrade plant cell wall polymers. Highest scores in these assays were achieved by a fungal isolate (Anthostomella sp.), two Streptomyces and one Bacillus bacterial isolates. Our study demonstrates that Costa Rican beetles harbor several types of cultivable microbes, some of which may be involved in symbiotic relationships that enable the insect to digest complex polymers such as lignocellulose.

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Bayesian phylogenetic tree of the ITS region sequences of fungi isolated from the gut of Costa Rican beetles.Numbers above branches represent their Bayesian-calculated posterior probabilities (two million generations, chain temperature  = 0.2, standard deviation <0.02). Numbers between brackets represent the number of isolates that shared the same sequence. Compress branches are colored in green. Red diamonds indicates positive cellulolytic activity.
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pone-0113303-g003: Bayesian phylogenetic tree of the ITS region sequences of fungi isolated from the gut of Costa Rican beetles.Numbers above branches represent their Bayesian-calculated posterior probabilities (two million generations, chain temperature  = 0.2, standard deviation <0.02). Numbers between brackets represent the number of isolates that shared the same sequence. Compress branches are colored in green. Red diamonds indicates positive cellulolytic activity.

Mentions: The fungal isolates represented the three fungal divisions Ascomycota, Basidiomycota and Zygomycota, and showed a high diversity spanning 23 families (two of which belong to the Basidiomycota and one to Zygomycota, see Table S1). Seventy-six% of the fungal isolates were classified as ascomycetes and 18% could not be classified using the ITS region as a molecular marker. The latter are distributed in several phylogenetic groups (see Figure 3). Among the ascomycetes, the most commonly recovered group was the Hypocreales with 26% of all isolates, including the most represented genera Trichoderma (9% of all isolates) and Nectria (7%). These isolates make up the largest cluster on the fungal phylogenetic tree (Figure 3). These fungi are known for being saprophytes that are adapted to thrive in diverse environments and therefore produce a wide array of enzymes. Other Hypocreales found were Metarhizium and Cordyceps, two genera of entomopathogenic fungi in the Clavicipitaceae family (Figure 3). We also isolated fungi belonging to Ophiostomatales: the Ophiostomataceae family (10%) makes up the second largest cluster in the phylogenetic tree and were grouped next to Hypocreales. Another group of Ascomycetes detected were the Chaetosphaeriales, with 8% of all isolates belonging to this group. The Basidiomycota isolates found (2.5%) belong to the family Dacrymycetaceae. The Zigomycota isolates (2.5%), belonged to the family Mucoraceae, including the genera Mucor and Rhizomucor, which could not be separated from the Ascomycetes using the ITS as molecular marker. Finally, a significant number of fungal isolates were not identified using the ITS marker. These isolates were distributed in several phylogenetic groups (Figure 3). To identify them or to confirm that they are new species, sequencing several rRNA genes as well as select primary metabolism genes may be necessary.


Uncovering the cultivable microbial diversity of costa rican beetles and its ability to break down plant cell wall components.

Vargas-Asensio G, Pinto-Tomas A, Rivera B, Hernandez M, Hernandez C, Soto-Montero S, Murillo C, Sherman DH, Tamayo-Castillo G - PLoS ONE (2014)

Bayesian phylogenetic tree of the ITS region sequences of fungi isolated from the gut of Costa Rican beetles.Numbers above branches represent their Bayesian-calculated posterior probabilities (two million generations, chain temperature  = 0.2, standard deviation <0.02). Numbers between brackets represent the number of isolates that shared the same sequence. Compress branches are colored in green. Red diamonds indicates positive cellulolytic activity.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4239062&req=5

pone-0113303-g003: Bayesian phylogenetic tree of the ITS region sequences of fungi isolated from the gut of Costa Rican beetles.Numbers above branches represent their Bayesian-calculated posterior probabilities (two million generations, chain temperature  = 0.2, standard deviation <0.02). Numbers between brackets represent the number of isolates that shared the same sequence. Compress branches are colored in green. Red diamonds indicates positive cellulolytic activity.
Mentions: The fungal isolates represented the three fungal divisions Ascomycota, Basidiomycota and Zygomycota, and showed a high diversity spanning 23 families (two of which belong to the Basidiomycota and one to Zygomycota, see Table S1). Seventy-six% of the fungal isolates were classified as ascomycetes and 18% could not be classified using the ITS region as a molecular marker. The latter are distributed in several phylogenetic groups (see Figure 3). Among the ascomycetes, the most commonly recovered group was the Hypocreales with 26% of all isolates, including the most represented genera Trichoderma (9% of all isolates) and Nectria (7%). These isolates make up the largest cluster on the fungal phylogenetic tree (Figure 3). These fungi are known for being saprophytes that are adapted to thrive in diverse environments and therefore produce a wide array of enzymes. Other Hypocreales found were Metarhizium and Cordyceps, two genera of entomopathogenic fungi in the Clavicipitaceae family (Figure 3). We also isolated fungi belonging to Ophiostomatales: the Ophiostomataceae family (10%) makes up the second largest cluster in the phylogenetic tree and were grouped next to Hypocreales. Another group of Ascomycetes detected were the Chaetosphaeriales, with 8% of all isolates belonging to this group. The Basidiomycota isolates found (2.5%) belong to the family Dacrymycetaceae. The Zigomycota isolates (2.5%), belonged to the family Mucoraceae, including the genera Mucor and Rhizomucor, which could not be separated from the Ascomycetes using the ITS as molecular marker. Finally, a significant number of fungal isolates were not identified using the ITS marker. These isolates were distributed in several phylogenetic groups (Figure 3). To identify them or to confirm that they are new species, sequencing several rRNA genes as well as select primary metabolism genes may be necessary.

Bottom Line: We isolated and described the cultivable fungi, actinomycetes and aerobic eubacteria associated with the gut of larvae and adults from six different beetle families colonizing decomposing logs in protected Costa Rican ecosystems.Highest scores in these assays were achieved by a fungal isolate (Anthostomella sp.), two Streptomyces and one Bacillus bacterial isolates.Our study demonstrates that Costa Rican beetles harbor several types of cultivable microbes, some of which may be involved in symbiotic relationships that enable the insect to digest complex polymers such as lignocellulose.

View Article: PubMed Central - PubMed

Affiliation: Instituto Nacional de Biodiversidad (INBio), Santo Domingo de Heredia, Costa Rica; Departamento de Bioquímica, Universidad de Costa Rica, San Pedro de Montes de Oca, Costa Rica.

ABSTRACT
Coleopterans are the most diverse insect order described to date. These organisms have acquired an array of survival mechanisms through their evolution, including highly efficient digestive systems. Therefore, the coleopteran intestinal microbiota constitutes an important source of novel plant cell wall-degrading enzymes with potential biotechnological applications. We isolated and described the cultivable fungi, actinomycetes and aerobic eubacteria associated with the gut of larvae and adults from six different beetle families colonizing decomposing logs in protected Costa Rican ecosystems. We obtained 611 isolates and performed phylogenetic analyses using the ITS region (fungi) and 16S rDNA (bacteria). The majority of fungal isolates belonged to the order Hypocreales (26% of 169 total), while the majority of actinomycetes belonged to the genus Streptomyces (86% of 241 total). Finally, we isolated 201 bacteria spanning 19 different families belonging into four phyla: Firmicutes, α, β and γ-proteobacteria. Subsequently, we focused on microbes isolated from Passalid beetles to test their ability to degrade plant cell wall polymers. Highest scores in these assays were achieved by a fungal isolate (Anthostomella sp.), two Streptomyces and one Bacillus bacterial isolates. Our study demonstrates that Costa Rican beetles harbor several types of cultivable microbes, some of which may be involved in symbiotic relationships that enable the insect to digest complex polymers such as lignocellulose.

Show MeSH