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. 2016 Jul 19;7:1135.
doi: 10.3389/fmicb.2016.01135. eCollection 2016.

Exploring the Diversity and Antimicrobial Potential of Marine Actinobacteria From the Comau Fjord in Northern Patagonia, Chile

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Free PMC article

Exploring the Diversity and Antimicrobial Potential of Marine Actinobacteria From the Comau Fjord in Northern Patagonia, Chile

Agustina Undabarrena et al. Front Microbiol. .
Free PMC article

Abstract

Bioprospecting natural products in marine bacteria from fjord environments are attractive due to their unique geographical features. Although, Actinobacteria are well known for producing a myriad of bioactive compounds, investigations regarding fjord-derived marine Actinobacteria are scarce. In this study, the diversity and biotechnological potential of Actinobacteria isolated from marine sediments within the Comau fjord, in Northern Chilean Patagonia, were assessed by culture-based approaches. The 16S rRNA gene sequences revealed that members phylogenetically related to the Micrococcaceae, Dermabacteraceae, Brevibacteriaceae, Corynebacteriaceae, Microbacteriaceae, Dietziaceae, Nocardiaceae, and Streptomycetaceae families were present at the Comau fjord. A high diversity of cultivable Actinobacteria (10 genera) was retrieved by using only five different isolation media. Four isolates belonging to Arthrobacter, Brevibacterium, Corynebacterium and Kocuria genera showed 16S rRNA gene identity <98.7% suggesting that they are novel species. Physiological features such as salt tolerance, artificial sea water requirement, growth temperature, pigmentation and antimicrobial activity were evaluated. Arthrobacter, Brachybacterium, Curtobacterium, Rhodococcus, and Streptomyces isolates showed strong inhibition against both Gram-negative Pseudomonas aeruginosa, Escherichia coli and Salmonella enterica and Gram-positive Staphylococcus aureus, Listeria monocytogenes. Antimicrobial activities in Brachybacterium, Curtobacterium, and Rhodococcus have been scarcely reported, suggesting that non-mycelial strains are a suitable source of bioactive compounds. In addition, all strains bear at least one of the biosynthetic genes coding for NRPS (91%), PKS I (18%), and PKS II (73%). Our results indicate that the Comau fjord is a promising source of novel Actinobacteria with biotechnological potential for producing biologically active compounds.

Keywords: Comau fjord; Northern Patagonia; antimicrobial activity; cultivable actinobacteria; marine sediments.

Figures

Figure 1
Figure 1
Geography of sampling sites for actinobacteria isolation from the Comau fjord in Northern Patagonia, Chile. Map of sampling locations within the Comau fjord (Los Lagos Region). Numbers indicate the sites where marine sediments were collected at the coast close to: Lilihuapi Island (1), Punta Llonco (2), Lloncochaigua River mouth (3), and Tambor Waterfall (4). Black dot indicates location of the Huinay Scientific Field Station.
Figure 2
Figure 2
Biodiversity of actinobacteria from the Comau fjord in Northern Patagonia. (A) Distribution of the relative abundance of the actinobacterial genera isolated. (B) Number of actinobacteria of various genera isolated using different culture media.
Figure 3
Figure 3
Antimicrobial activity of actinobacterial strains from the Comau fjord in Northern Patagonia. (A) Cross-streak method of Rhodococcus sp. H-CA8f showing different patterns of inhibition zones with several model bacteria. (B) Antimicrobial activity of actinobacterial strains using the cross-streak method. STAU, Staphylococcus aureus; LIMO, Listeria monocytogenes; PSAU, Pseudomonas aeruginosa; SAEN, Salmonella enterica; ESCO, Escherichia coli. I, ISP2-ASW media; T, TSA-ASW media.
Figure 4
Figure 4
Phylogenetic tree of representative actinobacterial strains isolated from the Comau fjord in Northern Patagonia, Chile. Neighbour-joining tree of 16S rRNA gene showing the three suborders within the phylum Actinobacteria. Node numbers represent the percentage of bootstrap replicates (1000 resampling) which supported the proposed branching order shown at consistent nodes (values below 50% were not shown). Gene sequence positions 55–1410 were considered, according to the Escherichia coli K12 (AP012306) 16S rRNA gene sequence numbering. Arrow points to the outgroup E. coli K12. GenBank accession numbers of 16S rRNA sequences are given in parentheses. Scale bar corresponds to 0.01 substitutions per nucleotide positions.
Figure 5
Figure 5
NaCl effect on actinobacterial growth. Upper panel: (A) Distribution of actinobacterial isolates and their ability to grow in LB medium with various percentages of NaCl. Bottom panel: As an example, the halophilic Brevibacterium sp. H-BE7 grown in LB medium containing: (B) 3.5%; (C) 5%; and (D) 10% NaCl concentrations.
Figure 6
Figure 6
Temperature effect on actinobacterial growth. Upper panel: (A) Distribution of actinobacterial isolates and their ability to grow in different temperatures. Bottom panel: As an example, actinobacterial strains grown in TSA-ASW medium at either 30°C (left) or 4°C (right), showing differences in pigmentations. (B) Dietzia sp. H-KA4; (C) Kocuria sp. H-KB5; (D) Brachybacterium sp. H-CG1.

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