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2017
Gallagher, KA, Wanger G, Henderson J, Llorente M, Hughes CC, Jensen PR.  2017.  Ecological implications of hypoxia-triggered shifts in secondary metabolism. Environmental Microbiology. 19:2182-2191.   10.1111/1462-2920.13700   AbstractWebsite

Members of the actinomycete genus Streptomyces are non-motile, filamentous bacteria that are well-known for the production of biomedically relevant secondary metabolites. While considered obligate aerobes, little is known about how these bacteria respond to periods of reduced oxygen availability in their natural habitats, which include soils and ocean sediments. Here, we provide evidence that the marine streptomycete strain CNQ-525 can reduce MnO2 via a diffusible mechanism. We investigated the effects of hypoxia on secondary metabolite production and observed a shift away from the antibiotic napyradiomycin towards 8-aminoflaviolin, an intermediate in the napyradiomycin biosynthetic pathway. We purified 8-amino-flaviolin and demonstrated that it is reversibly redox-active (midpoint potential -474.5 mV), indicating that it has the potential to function as an endogenous extracellular electron shuttle. This study provides evidence that environmentally triggered changes in secondary metabolite production may provide clues to the ecological functions of specific compounds, and that Gram-positive bacteria considered to be obligate aerobes may play previously unrecognized roles in biogeochemical cycling through mechanisms that include extracellular electron shuttling.

2016
Schorn, MA, Alanjary MM, Aguinaldo K, Korobeynikov A, Podell S, Patin N, Lincecum T, Jensen PR, Ziemert N, Moore BS.  2016.  Sequencing rare marine actinomycete genomes reveals high density of unique natural product biosynthetic gene clusters. Microbiology-Sgm. 162:2075-2086.   10.1099/mic.0.000386   AbstractWebsite

Traditional natural product discovery methods have nearly exhausted the accessible diversity of microbial chemicals, making new sources and techniques paramount in the search for new molecules. Marine actinomycete bacteria have recently come into the spotlight as fruitful producers of structurally diverse secondary metabolites, and remain relatively untapped. In this study, we sequenced 21 marine-derived actinomycete strains, rarely studied for their secondary metabolite potential and under-represented in current genomic databases. We found that genome size and phylogeny were good predictors of biosynthetic gene cluster diversity, with larger genomes rivalling the well-known marine producers in the Streptomyces and Salinispora genera. Genomes in the Micrococcineae suborder, however, had consistently the lowest number of biosynthetic gene clusters. By networking individual gene clusters into gene cluster families, we were able to computationally estimate the degree of novelty each genus contributed to the current sequence databases. Based on the similarity measures between all actinobacteria in the Joint Genome Institute's Atlas of Biosynthetic gene Clusters database, rare marine genera show a high degree of novelty and diversity, with Corynebacterium, Gordonia, Nocardiopsis, Saccharomonospora and Pseudonocardia genera representing the highest gene cluster diversity. This research validates that rare marine actinomycetes are important candidates for exploration, as they are relatively unstudied, and their relatives are historically rich in secondary metabolites.

Patin, NV, Duncan KR, Dorrestein PC, Jensen PR.  2016.  Competitive strategies differentiate closely related species of marine actinobacteria. Isme Journal. 10:478-490.   10.1038/ismej.2015.128   AbstractWebsite

Although competition, niche partitioning, and spatial isolation have been used to describe the ecology and evolution of macro-organisms, it is less clear to what extent these principles account for the extraordinary levels of bacterial diversity observed in nature. Ecological interactions among bacteria are particularly challenging to address due to methodological limitations and uncertainties over how to recognize fundamental units of diversity and link them to the functional traits and evolutionary processes that led to their divergence. Here we show that two closely related marine actinomycete species can be differentiated based on competitive strategies. Using a direct challenge assay to investigate inhibitory interactions with members of the bacterial community, we observed a temporal difference in the onset of inhibition. The majority of inhibitory activity exhibited by Salinispora arenicola occurred early in its growth cycle and was linked to antibiotic production. In contrast, most inhibition by Salinispora tropica occurred later in the growth cycle and was more commonly linked to nutrient depletion or other sources. Comparative genomics support these differences, with S. arenicola containing nearly twice the number of secondary metabolite biosynthetic gene clusters as S. tropica, indicating a greater potential for secondary metabolite production. In contrast, S. tropica is enriched in gene clusters associated with the acquisition of growth-limiting nutrients such as iron. Coupled with differences in growth rates, the results reveal that S. arenicola uses interference competition at the expense of growth, whereas S. tropica preferentially employs a strategy of exploitation competition. The results support the ecological divergence of two co-occurring and closely related species of marine bacteria by providing evidence they have evolved fundamentally different strategies to compete in marine sediments.

2014
Wietz, M, Millan-Aguinaga N, Jensen PR.  2014.  CRISPR-Cas systems in the marine actinomycete Salinispora: linkages with phage defense, microdiversity and biogeography. Bmc Genomics. 15   10.1186/1471-2164-15-936   AbstractWebsite

Background: Prokaryotic CRISPR-Cas systems confer resistance to viral infection and thus mediate bacteria-phage interactions. However, the distribution and functional diversity of CRISPRs among environmental bacteria remains largely unknown. Here, comparative genomics of 75 Salinispora strains provided insight into the diversity and distribution of CRISPR-Cas systems in a cosmopolitan marine actinomycete genus. Results: CRISPRs were found in all Salinispora strains, with the majority containing multiple loci and different Cas array subtypes. Of the six subtypes identified, three have not been previously described. A lower prophage frequency in S. arenicola was associated with a higher fraction of spacers matching Salinispora prophages compared to S. tropica, suggesting differing defensive capacities between Salinispora species. The occurrence of related prophages in strains from distant locations, as well as spacers matching those prophages inserted throughout spacer arrays, indicate recurring encounters with widely distributed phages over time. Linkages of CRISPR features with Salinispora microdiversity pointed to subclade-specific contacts with mobile genetic elements (MGEs). This included lineage-specific spacer deletions or insertions, which may reflect weak selective pressures to maintain immunity or distinct temporal interactions with MGEs, respectively. Biogeographic patterns in spacer and prophage distributions support the concept that Salinispora spp. encounter localized MGEs. Moreover, the presence of spacers matching housekeeping genes suggests that CRISPRs may have functions outside of viral defense. Conclusions: This study provides a comprehensive examination of CRISPR-Cas systems in a broadly distributed group of environmental bacteria. The ubiquity and diversity of CRISPRs in Salinispora suggests that CRISPR-mediated interactions with MGEs represent a major force in the ecology and evolution of this cosmopolitan marine actinomycete genus.

Ziemert, N, Lechner A, Wietz M, Millan-Aguinaga N, Chavarria KL, Jensen PR.  2014.  Diversity and evolution of secondary metabolism in the marine actinomycete genus Salinispora. Proceedings of the National Academy of Sciences of the United States of America. 111:E1130-E1139.   10.1073/pnas.1324161111   AbstractWebsite

Access to genome sequence data has challenged traditional natural product discovery paradigms by revealing that the products of most bacterial biosynthetic pathways have yet to be discovered. Despite the insight afforded by this technology, little is known about the diversity and distributions of natural product biosynthetic pathways among bacteria and how they evolve to generate structural diversity. Here we analyze genome sequence data derived from 75 strains of the marine actinomycete genus Salinispora for pathways associated with polyketide and nonribosomal peptide biosynthesis, the products of which account for some of today's most important medicines. The results reveal high levels of diversity, with a total of 124 pathways identified and 229 predicted with continued sequencing. Recent horizontal gene transfer accounts for the majority of pathways, which occur in only one or two strains. Acquired pathways are incorporated into genomic islands and are commonly exchanged within and between species. Acquisition and transfer events largely involve complete pathways, which subsequently evolve by gene gain, loss, and duplication followed by divergence. The exchange of similar pathway types at the precise chromosomal locations in different strains suggests that the mechanisms of integration include pathway-level homologous recombination. Despite extensive horizontal gene transfer there is clear evidence of species-level vertical inheritance, supporting the concept that secondary metabolites represent functional traits that help define Salinispora species. The plasticity of the Salinispora secondary metabolome provides an effective mechanism to maximize population-level secondary metabolite diversity while limiting the number of pathways maintained within any individual genome.

2013
Becerril-Espinosa, A, Freel KC, Jensen PR, Soria-Mercado IE.  2013.  Marine Actinobacteria from the Gulf of California: diversity, abundance and secondary metabolite biosynthetic potential. Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology. 103:809-819.   10.1007/s10482-012-9863-3   AbstractWebsite

The Gulf of California is a coastal marine ecosystem characterized as having abundant biological resources and a high level of endemism. In this work we report the isolation and characterization of Actinobacteria from different sites in the western Gulf of California. We collected 126 sediment samples and isolated on average 3.1-38.3 Actinobacterial strains from each sample. Phylogenetic analysis of 136 strains identified them as members of the genera Actinomadura, Micromonospora, Nocardiopsis, Nonomuraea, Saccharomonospora, Salinispora, Streptomyces and Verrucosispora. These strains were grouped into 26-56 operational taxonomic units (OTUs) based on 16S rRNA gene sequence identities of 98-100 %. At 98 % sequence identity, three OTUs appear to represent new taxa while nine (35 %) have only been reported from marine environments. Sixty-three strains required seawater for growth. These fell into two OTUs at the 98 % identity level and include one that failed to produce aerial hyphae and was only distantly related (a parts per thousand currency sign95.5 % 16S identity) to any previously cultured Streptomyces sp. Phylogenetic analyses of ketosynthase domains associated with polyketide synthase genes revealed sequences that ranged from 55 to 99 % nucleotide identity to experimentally characterized biosynthetic pathways suggesting that some may be associated with the production of new secondary metabolites. These results indicate that marine sediments from the Gulf of California harbor diverse Actinobacterial taxa with the potential to produce new secondary metabolites.

Ahmed, L, Jensen PR, Freel KC, Brown R, Jones AL, Kim BY, Goodfellow M.  2013.  Salinispora pacifica sp nov., an actinomycete from marine sediments. Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology. 103:1069-1078.   10.1007/s10482-013-9886-4   AbstractWebsite

A polyphasic analysis was carried out to clarify the taxonomic status of four marine actinomycete strains that share a phylogenetic relationship and phenotypic characteristics with the genus Salinispora. These strains formed a distinct lineage within the Salinispora 16S rRNA and gyrB trees and were found to possess a range of phenotypic properties and DNA: DNA hybridization values that distinguished them from the type strains of the two validly named species in this genus, Salinispora tropica (CNB-440(T), ATCC BAA-916(T)) and Salinispora arenicola (CNH-643(T), ATCC BAA-917(T)). The combined genotypic and phenotypic data support this conclusion. It is proposed that the strains be designated as Salinispora pacifica sp. nov., the type strain of which is CNR-114(T) (DSMZ YYYYT = KACC 17160(T)).

Gallagher, KA, Rauscher K, Ioca LP, Jensen PR.  2013.  Phylogenetic and chemical diversity of a hybrid-isoprenoid producing streptomycete lineage. Applied and Environmental Microbiology. 79:6894-6902.   10.1128/aem.01814-13   AbstractWebsite

Streptomyces species dedicate a large portion of their genomes to secondary metabolite biosynthesis. A diverse and largely marine-derived lineage within this genus has been designated MAR4 and identified as a prolific source of hybrid isoprenoid (HI) secondary metabolites. These terpenoid-containing compounds are common in nature but rarely observed as bacterial secondary metabolites. To assess the phylogenetic diversity of the MAR4 lineage, complementary culture-based and culture-independent techniques were applied to marine sediment samples collected off the Channel Islands, CA. The results, including those from an analysis of publically available sequence data and strains isolated as part of prior studies, placed 40 new strains in the MAR4 clade, of which 32 originated from marine sources. When combined with sequences cloned from environmental DNA, 28 MAR4 operational taxonomic units (0.01% genetic distance) were identified. Of these, 82% consisted exclusively of either cloned sequences or cultured strains, supporting the complementarity of these two approaches. Chemical analyses of diverse MAR4 strains revealed the production of five different HI structure classes. All 21 MAR4 strains tested produced at least one HI class, with most strains producing from two to four classes. The two major clades within the MAR4 lineage displayed distinct patterns in the structural classes and the number and amount of HIs produced, suggesting a relationship between taxonomy and secondary metabolite production. The production of HI secondary metabolites appears to be a phenotypic trait of the MAR4 lineage, which represents an emerging model with which to study the ecology and evolution of HI biosynthesis.

2012
Penn, K, Jensen PR.  2012.  Comparative genomics reveals evidence of marine adaptation in Salinispora species. BMC Genomics. 13   10.1186/1471-2164-13-86   AbstractWebsite

Background: Actinobacteria represent a consistent component of most marine bacterial communities yet little is known about the mechanisms by which these Gram-positive bacteria adapt to life in the marine environment. Here we employed a phylogenomic approach to identify marine adaptation genes in marine Actinobacteria. The focus was on the obligate marine actinomycete genus Salinispora and the identification of marine adaptation genes that have been acquired from other marine bacteria. Results: Functional annotation, comparative genomics, and evidence of a shared evolutionary history with bacteria from hyperosmotic environments were used to identify a pool of more than 50 marine adaptation genes. An Actinobacterial species tree was used to infer the likelihood of gene gain or loss in accounting for the distribution of each gene. Acquired marine adaptation genes were associated with electron transport, sodium and ABC transporters, and channels and pores. In addition, the loss of a mechanosensitive channel gene appears to have played a major role in the inability of Salinispora strains to grow following transfer to low osmotic strength media. Conclusions: The marine Actinobacteria for which genome sequences are available are broadly distributed throughout the Actinobacterial phylogenetic tree and closely related to non-marine forms suggesting they have been independently introduced relatively recently into the marine environment. It appears that the acquisition of transporters in Salinispora spp. represents a major marine adaptation while gene loss is proposed to play a role in the inability of this genus to survive outside of the marine environment. This study reveals fundamental differences between marine adaptations in Gram-positive and Gram-negative bacteria and no common genetic basis for marine adaptation among the Actinobacteria analyzed.

Bucarey, SA, Penn K, Paul L, Fenical W, Jensen PR.  2012.  Genetic Complementation of the Obligate Marine Actinobacterium Salinispora tropica with the Large Mechanosensitive Channel Gene mscL Rescues Cells from Osmotic Downshock. Applied and Environmental Microbiology. 78:4175-4182.   10.1128/aem.00577-12   AbstractWebsite

Marine actinomycetes in the genus Salinispora fail to grow when seawater is replaced with deionized (DI) water in complex growth media. While bioinformatic analyses have led to the identification of a number of candidate marine adaptation genes, there is currently no experimental evidence to support the genetic basis for the osmotic requirements associated with this taxon. One hypothesis is that the lineage-specific loss of mscL is responsible for the failure of strains to grow in media prepared with DI water. The mscL gene encodes a conserved transmembrane protein that reduces turgor pressure under conditions of acute osmotic downshock. In the present study, the mscL gene from a Micromonospora strain capable of growth on media prepared with DI water was transformed into S. tropica strain CNB-440. The single-copy, chromosomal genetic complementation yielded a recombinant Salinispora mscL(+) strain that demonstrated an increased capacity to survive osmotic downshock. The enhanced survival of the S. tropica transformant provides experimental evidence that the loss of mscL is associated with the failure of Salinispora spp. to grow in low-osmotic-strength media.

2011
Sun, P, Maloney KN, Nam SJ, Haste NM, Raju R, Aalbersberg W, Jensen PR, Nizet V, Hensler ME, Fenical W.  2011.  Fijimycins A-C, three antibacterial etamycin-class depsipeptides from a marine-derived Streptomyces sp. Bioorganic & Medicinal Chemistry. 19:6557-6562.   10.1016/j.bmc.2011.06.053   AbstractWebsite

Three new depsipeptides, fijimycins A-C (1-3), together with the known etamycin A (4), were isolated and identified from the fermentation broth of strain CNS-575, a Streptomyces sp. cultured from a marine sediment sample collected off Nasese, Fiji. The planar structures of the new fijimycins were assigned by combined interpretation of NMR and MS/MS spectroscopic data. These assignments were complicated by the fact that 1-3 occurred as complex amide conformational mixtures. The absolute configurations of the component amino acids were established using the Marfey's method. Fijimycins A-C, and etamycin A, were shown to possess significant in vitro antibacterial activity against three methicillin-resistant Staphylococcus aureus (MRSA) strains with MIC(100) values between 4 and 16 mu g mL(-1). (C) 2011 Elsevier Ltd. All rights reserved.

Haste, NM, Hughes CC, Tran DN, Fenical W, Jensen PR, Nizet V, Hensler ME.  2011.  Pharmacological Properties of the Marine Natural Product Marinopyrrole A against Methicillin-Resistant Staphylococcus aureus. Antimicrobial Agents and Chemotherapy. 55:3305-3312.   10.1128/aac.01211-10   AbstractWebsite

The ongoing spread of methicillin-resistant Staphylococcus aureus (MRSA) strains in hospital and community settings presents a great challenge to public health and illustrates the urgency of discovering new antibiotics. Marinopyrrole A is a member of a structurally novel class of compounds identified from a species of marine-derived streptomycetes with evidence of antistaphylococcal activity. We show that marinopyrrole A has potent concentration-dependent bactericidal activity against clinically relevant hospital-and community-acquired MRSA strains, a prolonged postantibiotic effect superior to that of the current first-line agents vancomycin and linezolid, and a favorable resistance profile. Marinopyrrole A showed limited toxicity to mammalian cell lines (at >20x MIC). However, its antibiotic activity against MRSA was effectively neutralized by 20% human serum. A variety of marinopyrrole analogs were isolated from culture or synthetically produced to try to overcome the inhibitory effect of serum. While many of these compounds retained potent bactericidal effect against MRSA, their activities were also inhibited by serum. Marinopyrrole A has significant affinity for plastic and may therefore have potential as a potent anti-MRSA agent in cutaneous, intracatheter, or antibiotic-lock applications.

2010
2009
Asolkar, RN, Freel KC, Jensen PR, Fenical W, Kondratyuk TP, Park EJ, Pezzuto JM.  2009.  Arenamides A-C, Cytotoxic NF kappa B Inhibitors from the Marine Actinomycete Salinispora arenicola. Journal of Natural Products. 72:396-402.   10.1021/np800617a   AbstractWebsite

Three new cyclohexadepsipeptides, arenamides A-C (1-3), were isolated from the fermentation broth of a marine bacterial strain identified as Salinispora arenicola. The planar structures of these compounds were assigned by detailed interpretation of NMR and MS/MS spectroscopic data. The absolute configurations of the amino acids, and those of the chiral centers on the side chain, were established by application of the Marfey and modified Mosher methods. The effect of arenamides A and B on NF kappa B activity was studied with stably transfected 293/NF kappa B-Luc human embryonic kidney cells induced by treatment with tumor necrosis factor (TNF). Arenamides A (1) and B (2) blocked TNF-induced activation in a dose- and time-dependent manner with IC(50) values of 3.7 and 1.7 mu M, respectively. In addition, the compounds inhibited nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production with lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Moderate cytotoxicity was observed with the human colon carcinoma cell line HCT-116, but no cytotoxic effect was noted with cultured RAW cells. Taken together, these data suggest that the chemoprevention and anti-inflammatory characteristics of arenamides A and B warrant further investigation.

2008
Boonlarppradab, C, Kauffman CA, Jensen PR, Fenical W.  2008.  Marineosins A and B, Cytotoxic Spiroaminals from a Marine-Derived Actinomycete. Organic Letters. 10:5505-5508.   10.1021/ol8020644   AbstractWebsite

Two novel spiroaminals, marineosins A and B (1, 2), containing two pyrrole functionalities, were isolated from cultures of a marine sediment-derived actinomycete related to the genus Streptomyces. The marineosins, which appear to be derived from unknown modifications of prodigiosin-like pigment pathways, showed significant inhibition of human colon carcinoma (HCT-116) in an in vitro assay (IC(50) = 0.5 mu M for marineosin A) and selective activities in diverse cancer cell types.

2006
Jensen, PR, Mafnas C.  2006.  Biogeography of the marine actinomycete Salinispora. Environmental Microbiology. 8:1881-1888.   10.1111/j.1462-2920.2006.01093.x   AbstractWebsite

Marine actinomycetes belonging to the genus Salinispora were cultured from marine sediments collected at six geographically distinct locations. Detailed phylogenetic analyses of both 16S rRNA and gyrB gene sequences reveal that this genus is comprised of three distinct but closely related clades corresponding to the species Salinispora tropica, Salinispora arenicola and a third species for which the name 'Salinispora pacifica' is proposed. Salinispora arenicola was cultured from all locations sampled and provides clear evidence for the cosmopolitan distribution of an individual bacterial species. The co-occurrence of S. arenicola with S. tropica and S. pacifica suggests that ecological differentiation as opposed to geographical isolation is driving speciation within the genus. All Salinispora strains cultured to date share greater than 99% 16S rRNA gene sequence identity and thus comprise what has been described as a microdiverse ribotype cluster. The description of this cluster as a new genus, containing multiple species, provides clear evidence that fine-scale 16S rDNA sequence analysis can be used to delineate among closely related species and that more conservative operational taxonomic unit values may significantly underestimate global species diversity.

Engel, S, Puglisi MP, Jensen PR, Fenical W.  2006.  Antimicrobial activities of extracts from tropical Atlantic marine plants against marine pathogens and saprophytes. Marine Biology. 149:991-1002.   10.1007/s00227-006-0264-x   AbstractWebsite

Studies investigating disease resistance in marine plants have indicated that secondary metabolites may have important defensive functions against harmful marine microorganisms. The goal of this study was to systematically screen extracts from marine plants for antimicrobial effects against marine pathogens and saprophytes. Lipophilic and hydrophilic extracts from species of 49 marine algae and 3 seagrasses collected in the tropical Atlantic were screened for antimicrobial activity against five ecologically relevant marine microorganisms from three separate kingdoms. These assay microbes consisted of the pathogenic fungus Lindra thalassiae, the saprophytic fungus Dendryphiella salina, the saprophytic stramenopiles, Halophytophthora spinosa and Schizochytrium aggregatum, and the pathogenic bacterium Pseudoaltermonas bacteriolytica. Overall, 90% of all species surveyed yielded extracts that were active against one or more, and 77% yielded extracts that were active against two or more assay microorganisms. Broad-spectrum activity against three or four assay microorganisms was observed in the extracts from 48 and 27% of all species, respectively. The green algae Halimeda copiosa and Penicillus capitatus (Chlorophyta) were the only species to yield extracts active against all assay microorganisms. Among all assay microorganisms, both fungi were the most resistant to the extracts tested, with less than 21% of all extracts inhibiting the growth of either L. thalassiae or D. salina. In contrast, over half of all lipophylic extracts were active against the stramenopiles H. spinosa and S. aggregatum, and the bacterium P. bacteriolytica. Growth sensitivity to hydrophilic extracts varied considerably between individual assay microorganisms. While 48% of all hydrophilic extracts were active against H. spinosa, 27% were active against P. bacteriolytica, and only 14% were active against S. aggregatum. Overall, more lipophilic extracts inhibited microbial growth than hydrophilic extracts. The variability observed in the antimicrobial effects of individual extracts against each assay microorganism reflects the importance of choosing appropriate test microbes in assays from which ecologically relevant information is sought. Results from this survey demonstrate that antimicrobial activities are prevalent among extracts from marine algae and seagrasses, suggesting that antimicrobial chemical defenses are widespread among marine plants.

2005
Oh, DC, Jensen PR, Kauffman CA, Fenical W.  2005.  Libertellenones A-D: Induction of cytotoxic diterpenoid biosynthesis by marine microbial competition. Bioorganic & Medicinal Chemistry. 13:5267-5273.   10.1016/j.bmc.2005.05.068   AbstractWebsite

The induction of biosynthesis of four new diterpenoids was observed following the addition of a marine alpha-proteobacterium to an established culture of the marine-derived fungus Libertella sp. The fungal strain and the marine bacterium, cultured alone, do not produce diterpenoid metabolites. The induced diterpenoids, libertellenones A-D, are cross-conjugated ketones of the pimarane class. The libertellenones show varying levels of cytotoxicity against the HCT-116 human adenocarcinoma cell line with libertellenone D being the most potent (IC50 = 0.76 mu M). (c) 2005 Elsevier Ltd. All rights reserved.

2003
Pimentel-Elardo, S, Wehrl M, Friedrich AB, Jensen PR, Hentschel U.  2003.  Isolation of planctomycetes from Aplysina sponges. Aquatic Microbial Ecology. 33:239-245.   10.3354/ame033239   AbstractWebsite

There is mounting molecular evidence that bacteria belonging to the phylum Planctomycetes are abundant in marine sponges including members of the genus Aplysina. In an attempt to culture planctomycete bacteria from Aplysina sponges, 116 bacterial strains were isolated on selective oligotrophic media. Screening of the strain collection by fluorescence in situ hybridization with the planctomycete-specific probe Pla46 yielded 3 positive candidates. Nearly complete sequencing of the respective 16S rRNA genes revealed that the isolates were affiliated with 2 distinct clusters of the genus Pirellula: 1 isolate was obtained from a Mediterranean sponge, 1 from a Caribbean sponge and a third from Caribbean seawater. To our knowledge this is the first report of cultured Planctomycetes from marine sponges. The isolates grew slowly on oligotrophic media and failed to grow on nutrient-rich media. Pirellula sp. Strain 797 was pink-pigmented while the other 2 isolates, 16 and 81, were non-pigmented. Transmission electron microscopy revealed a pear- or droplet-shaped cell morphology that is characteristic of the genus Pirellula. The application of strain-specific oligonucleotide probes to sponge tissue cryosections showed that the isolates contribute only a minor fraction to the total microbial community that is associated with Aplysina spp. sponges.

1996
Jensen, PR, Harvell CD, Wirtz K, Fenical W.  1996.  Antimicrobial activity of extracts of Caribbean gorgonian corals. Marine Biology. 125:411-419.   10.1007/bf00346321   AbstractWebsite

Extracts of 39 species of Caribbean gorgonians were tested for antimicrobial activity against 15 strains of marine bacteria. The bacteria consisted of three opportunistic pathogens, Vibrio parahaemolyticus, Leucothrix mucor, and Aerococcus viridans, and 12 strains isolated from either healthy or decayed gorgonians. Overall, only 15% (79 out of 544) of the tests resulted in antibacterial activity with 33% (13 out of 39) of the gorgonians inhibiting only one bacterial strain and 23% (9 out of 39) showing no activity. The extracts of four Pseudopterogorgia species showed relatively high levels of activity, inhibiting 43 to 86% of the bacterial strains. The potency of the active Pseudopterogorgia species was variable, however, and three additional Pseudopterogorgia species were inactive against all bacterial strains. With the exception of one sensitive strain, Vibrio species were resistant to gorgonian metabolites. Our results indicate that organic extracts of most Caribbean gorgonians do not possess potent, broad-spectrum antibacterial activity inhibitory to the growth of opportunistic marine pathogens and bacteria associated with healthy and decayed gorgonian surfaces. These findings suggest that the inhibition of bacterial growth is not the primary ecological function of gorgonian secondary metabolites and that bacteria may not be important selective agents in the evolution of gorgonian secondary chemistry.

1995
Toske, SG, Jensen PR, Kauffman CA, Fenical W.  1995.  Elijopyrones a-D - New Alpha-Pyrones from a Marine Actinomycete. Natural Product Letters. 6:303-308.   10.1080/10575639508043175   AbstractWebsite

Elijopyrones A-D (1-4) were isolated from a cultured marine actinomycete (isolate CNB-880). The producing strain was obtained from a sediment collected from the San Elijo Lagoon, Cardiff, California. The structures of the new compounds were determined by comprehensive spectral analyses.

1994
Trischman, JA, Tapiolas DM, Jensen PR, Dwight R, Fenical W, McKee TC, Ireland CM, Stout TJ, Clardy J.  1994.  Salinamide-a and Salinamide-B - Antiinflammatory Depsipeptides from a Marine Streptomycete. Journal of the American Chemical Society. 116:757-758.   10.1021/ja00081a042   Website