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Isolation, abundance and phylogenetic affiliation of endophytic actinomycetes associated with medicinal plants and screening for their in vitro antimicrobial biosynthetic potential.

Passari AK, Mishra VK, Saikia R, Gupta VK, Singh BP - Front Microbiol (2015)

Bottom Line: Microorganisms associated with medicinal plants are of interest as the producers of important bioactive compounds.Further, antimicrobial properties and antibiotic sensitivity assay in combination with the results of amplification of biosynthetic genes polyketide synthase (PKS-I) and non-ribosomal peptide synthetase (NRPS) showed that the endophytic actinomycetes associated with the selected medicinal plants have broad-spectrum antimicrobial activity.Our results emphasize that endophytic actinomycetes associated with medicinal plants are an unexplored resource for the discovery of biologically active compounds.

View Article: PubMed Central - PubMed

Affiliation: Molecular Microbiology and Systematics Laboratory, Department of Biotechnology, Mizoram University Aizawl, India.

ABSTRACT
Microorganisms associated with medicinal plants are of interest as the producers of important bioactive compounds. To date, the diversity of culturable endophytic actinomycetes associated with medicinal plants is in its initial phase of exploration. In this study, 42 endophytic actinomycetes were isolated from different organs of seven selected medicinal plants. The highest number of isolates (n = 22, 52.3%) of actinomycetes was isolated from roots, followed by stems (n = 9, 21.4%), leaves (n = 6, 14.2%), flowers (n = 3, 7.1%), and petioles (n = 2, 4.7%). The genus Streptomyces was the most dominant among the isolates (66.6%) in both the locations (Dampa TRF and Phawngpuii NP, Mizoram, India). From a total of 42 isolates, 22 isolates were selected for further studies based on their ability to inhibit one of the tested human bacterial or fungal pathogen. Selected isolates were identified based on 16S rRNA gene analysis and subsequently the isolates were grouped to four different genera; Streptomyces, Brevibacterium, Microbacterium, and Leifsonia. Antibiotic sensitivity assay was performed to understand the responsible antimicrobials present in the isolates showing the antimicrobial activities and revealed that the isolates were mostly resistant to penicillin G and ampicillin. Further, antimicrobial properties and antibiotic sensitivity assay in combination with the results of amplification of biosynthetic genes polyketide synthase (PKS-I) and non-ribosomal peptide synthetase (NRPS) showed that the endophytic actinomycetes associated with the selected medicinal plants have broad-spectrum antimicrobial activity. This is the first report of the isolation of Brevibacterium sp., Microbacterium sp., and Leifsonia xyli from endophytic environments of medicinal plants, Mirabilis jalapa and Clerodendrum colebrookianum. Our results emphasize that endophytic actinomycetes associated with medicinal plants are an unexplored resource for the discovery of biologically active compounds.

No MeSH data available.


Neighbor-joining phylogenetic tree based on 16S rRNA gene of endophytic actinomycetes. Numbers at branches indicate bootstrap values of neighbor joining analysis (>50%) from 1000 replicates.
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Figure 5: Neighbor-joining phylogenetic tree based on 16S rRNA gene of endophytic actinomycetes. Numbers at branches indicate bootstrap values of neighbor joining analysis (>50%) from 1000 replicates.

Mentions: To investigate the relationships among the more promising endophytic actinomycetes isolate, 16S rRNA gene sequences were aligned along with the sequences of type strains retrieved from DDBJ/EMBL/NCBI GenBank databases. The results showed that the isolates were classified into four families and five genera. Most of the isolates grouped into Streptomycetaceae (68.18%), followed by Microbacteriaceae (22.7%), Brevibacteriaceae, and Actinomycetaceae (4.5% each). Analysis of the 16S rRNA gene sequence by BlastN with 99–100% similarity confirmed that 15 isolates could be members of genus Streptomyces. The sequences of the 4 isolates (BPSAC21, BPSAC27, BPSAC28, and BPSAC29) showed 96–100% identity to the sequences retrieved from genus Microbacterium and isolates BPSAC24, BPSAC35, and BPSAC37 showed high identity (99% each) to the genus Leifsonia, Brevibacterium, and Actinomycete, respectively (Table 3). Maximum-likelihood and neighbor-joining methods were used for the construction of phylogenetic tree. The topology of the phylogenetic tree generated by both methods showed that all Streptomyces forms a major clade I, along with the type strains retrieved from databases with the exception to Actinomycete, which also falls in the same clade under a bootstrap support value of 76 and 98%. Most of the putative species in the genera Brevibacterium, Leifsonia, and Microbacterium, clustering to form another clade II. The neighbor-joining analysis did not cluster Leifsonia and Microbacterium together, though they belong to same family, but maximum-likelihood clearly clusters both genera together (Figures 5, 6).


Isolation, abundance and phylogenetic affiliation of endophytic actinomycetes associated with medicinal plants and screening for their in vitro antimicrobial biosynthetic potential.

Passari AK, Mishra VK, Saikia R, Gupta VK, Singh BP - Front Microbiol (2015)

Neighbor-joining phylogenetic tree based on 16S rRNA gene of endophytic actinomycetes. Numbers at branches indicate bootstrap values of neighbor joining analysis (>50%) from 1000 replicates.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388002&req=5

Figure 5: Neighbor-joining phylogenetic tree based on 16S rRNA gene of endophytic actinomycetes. Numbers at branches indicate bootstrap values of neighbor joining analysis (>50%) from 1000 replicates.
Mentions: To investigate the relationships among the more promising endophytic actinomycetes isolate, 16S rRNA gene sequences were aligned along with the sequences of type strains retrieved from DDBJ/EMBL/NCBI GenBank databases. The results showed that the isolates were classified into four families and five genera. Most of the isolates grouped into Streptomycetaceae (68.18%), followed by Microbacteriaceae (22.7%), Brevibacteriaceae, and Actinomycetaceae (4.5% each). Analysis of the 16S rRNA gene sequence by BlastN with 99–100% similarity confirmed that 15 isolates could be members of genus Streptomyces. The sequences of the 4 isolates (BPSAC21, BPSAC27, BPSAC28, and BPSAC29) showed 96–100% identity to the sequences retrieved from genus Microbacterium and isolates BPSAC24, BPSAC35, and BPSAC37 showed high identity (99% each) to the genus Leifsonia, Brevibacterium, and Actinomycete, respectively (Table 3). Maximum-likelihood and neighbor-joining methods were used for the construction of phylogenetic tree. The topology of the phylogenetic tree generated by both methods showed that all Streptomyces forms a major clade I, along with the type strains retrieved from databases with the exception to Actinomycete, which also falls in the same clade under a bootstrap support value of 76 and 98%. Most of the putative species in the genera Brevibacterium, Leifsonia, and Microbacterium, clustering to form another clade II. The neighbor-joining analysis did not cluster Leifsonia and Microbacterium together, though they belong to same family, but maximum-likelihood clearly clusters both genera together (Figures 5, 6).

Bottom Line: Microorganisms associated with medicinal plants are of interest as the producers of important bioactive compounds.Further, antimicrobial properties and antibiotic sensitivity assay in combination with the results of amplification of biosynthetic genes polyketide synthase (PKS-I) and non-ribosomal peptide synthetase (NRPS) showed that the endophytic actinomycetes associated with the selected medicinal plants have broad-spectrum antimicrobial activity.Our results emphasize that endophytic actinomycetes associated with medicinal plants are an unexplored resource for the discovery of biologically active compounds.

View Article: PubMed Central - PubMed

Affiliation: Molecular Microbiology and Systematics Laboratory, Department of Biotechnology, Mizoram University Aizawl, India.

ABSTRACT
Microorganisms associated with medicinal plants are of interest as the producers of important bioactive compounds. To date, the diversity of culturable endophytic actinomycetes associated with medicinal plants is in its initial phase of exploration. In this study, 42 endophytic actinomycetes were isolated from different organs of seven selected medicinal plants. The highest number of isolates (n = 22, 52.3%) of actinomycetes was isolated from roots, followed by stems (n = 9, 21.4%), leaves (n = 6, 14.2%), flowers (n = 3, 7.1%), and petioles (n = 2, 4.7%). The genus Streptomyces was the most dominant among the isolates (66.6%) in both the locations (Dampa TRF and Phawngpuii NP, Mizoram, India). From a total of 42 isolates, 22 isolates were selected for further studies based on their ability to inhibit one of the tested human bacterial or fungal pathogen. Selected isolates were identified based on 16S rRNA gene analysis and subsequently the isolates were grouped to four different genera; Streptomyces, Brevibacterium, Microbacterium, and Leifsonia. Antibiotic sensitivity assay was performed to understand the responsible antimicrobials present in the isolates showing the antimicrobial activities and revealed that the isolates were mostly resistant to penicillin G and ampicillin. Further, antimicrobial properties and antibiotic sensitivity assay in combination with the results of amplification of biosynthetic genes polyketide synthase (PKS-I) and non-ribosomal peptide synthetase (NRPS) showed that the endophytic actinomycetes associated with the selected medicinal plants have broad-spectrum antimicrobial activity. This is the first report of the isolation of Brevibacterium sp., Microbacterium sp., and Leifsonia xyli from endophytic environments of medicinal plants, Mirabilis jalapa and Clerodendrum colebrookianum. Our results emphasize that endophytic actinomycetes associated with medicinal plants are an unexplored resource for the discovery of biologically active compounds.

No MeSH data available.