AUTHOR=Aw Yoong-Kit , Ong Kuan-Shion , Lee Learn-Han , Cheow Yuen-Lin , Yule Catherine M. , Lee Sui-Mae 

TITLE=Newly Isolated Paenibacillus tyrfis sp. nov., from Malaysian Tropical Peat Swamp Soil with Broad Spectrum Antimicrobial Activity

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.00219

DOI=10.3389/fmicb.2016.00219

ISSN=1664-302X

ABSTRACT=<p>Emergence of antimicrobial resistance coupled with the slowdown in discovery of new antimicrobial compounds points to serious consequences for human health. Therefore, scientists are looking for new antimicrobial compounds from unique and understudied ecosystems such as tropical peat swamp forests. Over the course of isolating antimicrobial producing bacteria from North Selangor tropical peat swamp forest, Malaysia, a Gram variable, rod shaped, endospore forming, facultative anaerobic novel strain MSt1<sup>T</sup> that exerts potent and broad spectrum antimicrobial activity was isolated. Phylogenetic analysis using 16S rRNA gene sequences showed that strain MSt1<sup>T</sup> belonged to the genus <italic>Paenibacillus</italic> with the highest similarity to <italic>Paenibacillus elgii</italic> SD17<sup>T</sup> (99.5%). Whole genome comparison between strain MSt1<sup>T</sup> with its closely related species using average nucleotide identity (ANI) revealed that similarity between strain MSt1<sup>T</sup> with <italic>P. elgii</italic> B69 (93.45%) and <italic>Paenibacillus ehimensis</italic> A2 (90.42%) was below the recommended threshold of 95%. Further analysis using <italic>in silico</italic> pairwise DDH also showed that similarity between strain MSt1<sup>T</sup> with <italic>P. elgii</italic> B69 (55.4%) and <italic>P. ehimensis</italic> A2 (43.7%) was below the recommended threshold of 70%. Strain MSt1<sup>T</sup> contained <italic>meso</italic>-diaminopilemic acid in the cell wall and MK-7 as the major menaquinone. The major fatty acids of strain MSt1<sup>T</sup> were anteiso-C<sub>15:0</sub> (48.2%) and C<sub>16:0</sub> (29.0%) whereas the polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unknown lipid, two unknown glycolipids, and one unknown phospholipid. Total DNA G+C content of strain MSt1<sup>T</sup> was 51.5 mol%. The extract from strain MSt1<sup>T</sup> exerted strong antimicrobial activity against <italic>Escherichia coli</italic> ATCC 25922 (MIC = 1.5 μg/mL), MRSA ATCC 700699 (MIC = 25 μg/mL) and <italic>Candida albicans</italic> IMR (MIC = 12.5 μg/mL). Partially purified active fraction exerted a strong effect against <italic>E. coli</italic> ATCC 25922 resulting in cell rupture when viewed with SEM. Based on distinctive taxonomic differences between strain MSt1<sup>T</sup> when compared to its closely related type species, we propose that strain MSt1<sup>T</sup> represents a novel species within the genus of <italic>Paenibacillus</italic>, for which the name <italic>Paenibacillus tyrfis</italic> sp. nov. (= DSM 100708<sup>T</sup> = MCCC 1K01247<sup>T</sup>) is proposed.</p>