Discovery of the Lipopeptides Albubactins A-H from RKJM0023 via Chemical Elicitation with Rhamnolipids and Synthesis of Albubactin A.

The marine tunicate-derived RKJM0023 was cultured in the presence of a rhamnolipid mixture in an effort to elicit the production of silent natural products. MS/MS-based molecular networking analysis enhanced with nonparametric statistics highlighted the upregulation of a molecular cluster (Kruskal-Wallis = 1.6 e for ) in which no MS/MS features had library matches.

Discovery of Acyl-Surugamide A2 from Marine RKJM-0023-A New Cyclic Nonribosomal Peptide Containing an N-ε-acetyl-L-lysine Residue.

We report the discovery of a novel cyclic nonribosomal peptide (NRP), acyl-surugamide A2, from a marine-derived RKJM-0023 (CP133227). The structure of acyl-surugamide A2 was elucidated using a combination of NMR spectroscopy, MS2 fragmentation analysis, and comparative analysis of the biosynthetic gene cluster. Acyl-surugamide A2 contains all eight core amino acids of surugamide A, with a modified N-ε-acetyl-L-lysine residue.

Mechanism of action of pseudopteroxazole and pseudopterosin G: Diterpenes from marine origin.

Pseudopteroxazole (Ptx) and the pseudopterosins are marine natural products with promising antibacterial potential. While Ptx has attracted interest for its antimycobacterial activity, pseudopterosins are active against several clinically relevant pathogens. Both compound classes exhibit low cytotoxicity and accessibility to targeted synthesis, yet their antibacterial mechanisms remain elusive.

Discovery of Levesquamide B through Global Natural Product Social Molecular Networking.

Levesquamide A is an isothiazolinone-containing anti-tubercular natural product isolated from sp. RKND-216. Through the use of Global Natural Product Social Molecular Networking (GNPS), additional members of the levesquamide family were identified (B-G).

Microfabrication of a micron-scale microbial-domestication pod for cultivation of marine bacteria.

Through the hyphenation of microfabrication, microfluidics and microbiology, we report the development of a μMicrobial-Domestication Pod (μMD Pod). This cultivation device facilitates cell signaling from neighbouring species and interactions with environmental stimuli for marine bacterial growth to overcome current barriers faced by standard laboratory cultivation methods.

Draft Genome Sequence of sp. Strain RKCA744, Isolated from the Arauca River, Colombia.

sp. strain RKCA744 was isolated from sediment collected from the Arauca River, Colombia.

Draft Genome Sequences of Three Streptomycetes Isolated from Frobisher Bay Marine Sediments.

Three strains (RKAG290, RKAG293, and RKAG337) were isolated from intertidal marine sediments of Frobisher Bay (Canada).

Microencapsulation and incubation methodology for the cultivation of marine bacteria.

Environmental microorganisms are important sources of biotechnology innovations; however, the discovery process is hampered by the inability to culture the overwhelming majority of microbes. To drive the discovery of new biotechnology products from previously unculturable microbes, several methods such as modification of media composition, incubation conditions, single-cell isolation, and incubation, have been employed to improve microbial recovery from environmental samples. To improve microbial recovery, we examined the effect of microencapsulation followed by incubation on the abundance, viability, and diversity of bacteria recovered from marine sediment.

Effects of Matrix Composition and Temperature on Viability and Metabolic Activity of Microencapsulated Marine Bacteria.

To enhance the discovery of novel natural products, various innovations have been developed to aid in the cultivation of previously unculturable microbial species. One approach involving the microencapsulation of bacteria has been gaining popularity as a new cultivation technique, with promising applications. Previous studies demonstrated the success of bacterial encapsulation; however, they highlighted that a key limitation of encapsulating bacteria within agarose is the high temperature required for encapsulation.

Complete Genome Sequence of Phage ϕRKBJ001 Isolated from Prince Edward Island, Canada.

We reported here the complete genome sequence of phage ϕRKBJ001 that was isolated from a saltwater marsh on Prince Edward Island, Canada, using the sp. strain RKBHB0173. Based on electron microscopy and genomic analysis, this phage belongs to the family and the BN phage cluster.

Comparative Microbiome and Metabolome Analyses of the Marine Tunicate from Native and Invaded Habitats.

Massive fouling by the invasive ascidian in Prince Edward Island (PEI, Canada) has been causing devastating losses to the local blue mussel farms. In order to gain first insights into so far unexplored factors that may contribute to the invasiveness of in PEI, we undertook comparative microbiome and metabolome studies on specific tissues from populations collected in invaded (PEI) and native regions (Helgoland and Kiel, Germany). Microbial community analyses and untargeted metabolomics revealed clear location- and tissue-specific patterns showing that biogeography and the sampled tissue shape the microbiome and metabolome of .

Development of a microbe domestication pod (MD Pod) for in situ cultivation of micro-encapsulated marine bacteria.

Microbial marine natural products hold significant potential for the discovery of new bioactive therapeutics such as antibiotics. Unfortunately, this discovery is hindered by the inability to culture the majority of microbes using traditional laboratory approaches. While many new methods have been developed to increase cultivability, a high-throughput in situ incubation chamber capable of simultaneously isolating individual microbes while allowing cellular communication has not previously been reported.

Metabolomic Comparison and Assessment of Co-cultivation and a Heat-Killed Inducer Strategy in Activation of Cryptic Biosynthetic Pathways.

Co-cultivation has been used as a promising tool to turn on or up-regulate cryptic biosynthetic pathways for microbial natural product discovery. Recently, a modified culturing strategy similar to co-cultivation was investigated, where heat-killed inducer cultures were supplemented to the culture medium of producer fermentations to induce cryptic pathways. In the present study, the repeatability and effectiveness of both methods in turning on cryptic biosynthetic pathways were unbiasedly assessed using UHPLC-HRESIMS-based metabolomics analysis.

Guanahanolide A, a Meroterpenoid with a Sesterterpene Skeleton from Coral-Derived sp.

A meroterpenoid, guanahanolide A (), was purified from a fermentation extract of sp. RKBH-B7. The planar structure of guanahanolide A () was elucidated by NMR spectroscopy, revealing a meroterpenoid comprised of an unprecedented sesterterpene skeleton.

Discovery of an Isothiazolinone-Containing Antitubercular Natural Product Levesquamide.

Antitubercular agent levesquamide is a new polyketide-nonribosomal peptide (PK-NRP) hybrid marine natural product isolated from sp. RKND-216. The structure contains a rare isothiazolinone moiety which has only been reported in collismycin SN.

An Ichip-Domesticated Sponge Bacterium Produces an -Acyltyrosine Bearing an α-Methyl Substituent.

The ichip (isolation chip) was employed for the first time in a marine sponge (), and a putatively new bacterial species, sp. RKMC-009, was isolated. Strain RKMC-009 produces a novel -acyltyrosine () that is appended with a rare α-methyl substituent within the aminoacyl moiety and also exhibits Gram-positive antibacterial activity.

Draft Genome Sequence of Streptomyces sp. Strain RKND-216, an Antibiotic Producer Isolated from Marine Sediment in Prince Edward Island, Canada.

sp. strain RKND-216 was isolated from marine sediment collected in Prince Edward Island, Canada, and produces a putatively novel bioactive natural product with antitubercular activity. The genome assembly consists of two contigs covering 5.

Draft Genome Sequence of sp. Strain RKMC-009, Isolated from via Culturing Using an Isolation Chip Diffusion Chamber.

We report the draft whole-genome sequence of sp. strain RKMC-009, which was isolated from the sponge in San Salvador, The Bahamas, using an isolation chip (ichip). Automated biosynthetic gene cluster analysis using antiSMASH 4.

Terrosamycins A and B, Bioactive Polyether Ionophores from sp. RKND004 from Prince Edward Island Sediment.

Terrosamycins A () and B (), two polycyclic polyether natural products, were purified from the fermentation broth of sp. RKND004 isolated from Prince Edward Island sediment. The one strain-many compounds (OSMAC) approach coupled with UPLC-HRMS-based metabolomics screening led to the identification of these compounds.

Secreted lipases from Malassezia globosa: recombinant expression and determination of their substrate specificities.

Malassezia globosa, which is associated with skin conditions such as dandruff and seborrhoeic dermatitis, possesses 13 secreted lipases, but only MgLip1, MgMDL2 and MgLip2 have been characterized. To understand the substrate preferences of these lipases and by extension their potential role in colonizing human skin, we expressed all 13 predicted secreted lipases in Pichia pastoris and evaluated their ability to utilize mono-, di- and triolein substrates. The M.

Discovery of keratinases using bacteria isolated from marine environments.

Bacteria are important for the biodegradation of keratin. Thus, a workflow to isolate keratin-degrading bacteria utilizing an optimized azo-keratin assay was established. Deteriorated feather samples, collected in marine shoreline environments from the intertidal zone, yielded 50 unique bacterial isolates exhibiting keratin degradation when feather meal was supplied as keratin substrate.

Bioprospecting from marine sediments of New Brunswick, Canada: exploring the relationship between total bacterial diversity and actinobacteria diversity.

Actinomycetes are an important resource for the discovery of natural products with therapeutic properties. Bioprospecting for actinomycetes typically proceeds without a priori knowledge of the bacterial diversity present in sampled habitats. In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete diversity, and thus serve as a powerful tool in guiding future bioprospecting efforts.

Investigation of the biosynthesis of the pipecolate moiety of neuroprotective polyketide meridamycin.

Biogenesis of the pipecolate moiety of neuroprotective agent meridamycin in Streptomyces sp. NRRL30748 was investigated in feeding studies using lysine specifically labeled with (15)N at the α-amino or the ε-amino nitrogen position. Fourier transform mass spectrometry analysis with ultra-high mass resolving power and accurate mass measurement capability was employed to resolve the (15)N peak of labeled meridamycin from the (13)C peak of unlabeled meridamycin, allowing the precise calculation of labeling contents under each condition.

Rapid cloning and heterologous expression of the meridamycin biosynthetic gene cluster using a versatile Escherichia coli-streptomyces artificial chromosome vector, pSBAC.

Expression of biosynthetic pathways in heterologous hosts is an emerging approach to expedite production improvement and biosynthetic modification of natural products derived from microbial secondary metabolites. Herein we describe the development of a versatile Escherichia coli-Streptomyces shuttle Bacterial Artificial Chromosomal (BAC) conjugation vector, pSBAC, to facilitate the cloning, genetic manipulation, and heterologous expression of actinomycetes secondary metabolite biosynthetic gene clusters. The utility of pSBAC was demonstrated through the rapid cloning and heterologous expression of one of the largest polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) biosynthetic pathways: the meridamycin biosynthesis gene cluster (mer).

Investigating the biosynthetic origin of the nitro group in pyrrolomycins.

Feasible modes of introducing the nitro group into pyrrolomycin antibiotics were investigated based on incorporation of (15)N-labeled arginine and proline into dioxapyrrolomycin, produced by the actinomycete culture LL-F42248. Biosynthesis of nitrated pyrrolomycins was unaffected by the presence of nitric oxide synthase (NOS) inhibitors. The culture was able to grow in nitrogen-free (minimal) media and produce nitrated secondary metabolites.