A screening of marine bacteria for antimicrobial activity resulted in the isolation of Bacillus p... more A screening of marine bacteria for antimicrobial activity resulted in the isolation of Bacillus pumilus (SP21) from a sediment sample collected in the Bahamas. A bioassay-guided fractionation led to the isolation of five surfactin analogs, glycocholic acid, amicoumacins A and B in addition to three new compounds named lipoamides A-C. The chemical structure of all the bioactive compounds was elucidated using spectroscopic methods including 2D NMR and MS. The antimicrobial activity of each compound was evaluated against a panel of pathogens and is reported herein.
We report here the draft genome sequence of Kitasatospora griseola strain MF730-N6, a known produ... more We report here the draft genome sequence of Kitasatospora griseola strain MF730-N6, a known producer of bafilomycin, terpentecin, and satosporins. The current assembly comprises 8 contigs covering 7.97 Mb. Genome annotation revealed 7,225 protein coding sequences, 100 tRNAs, 40 rRNA genes, and 23 secondary metabolite biosynthetic gene clusters.
Melanoma causes the highest rate of skin cancer related fatalities. If detected and treated early... more Melanoma causes the highest rate of skin cancer related fatalities. If detected and treated early, melanoma is mostly curable. Unfortunately, once metastasis has occurred melanoma is often fatal. The biochemical pathways involved in the development from primary to metastatic melanoma is an area under intense investigation. A high-throughput proteomics approach has been applied to better understand the processes that underlie tumor formation and progression. Analyses of global melanoma proteome expression patterns are compared between the primary melanoma cell line WM-115 and the metastatic melanoma cell line WM-266-4, where both cell lines derived from the same patient. Total cell lysates were separated by two dimensional-gel electrophoresis (2DE). After protein differential expression analysis, protein spots of interest were excised, digested with trypsin and analyzed by LC-MS/MS. The mass data were searched against an in-house NCBInr database using the Mascot search engine for pro...
Two novel β-lactone-containing natural products, cystargolides A (1) and B (2), were isolated fro... more Two novel β-lactone-containing natural products, cystargolides A (1) and B (2), were isolated from the actinomycete Kitasatospora cystarginea. The production of these two natural products was highlighted using a methodology associating liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis and the statistical analysis tool principal component analysis (PCA). Their structures were elucidated by interpretation of NMR experiments and tandem mass spectrometry. The absolute configurations of the amino acid residues were determined using Marfey's method, and the relative configurations of the β-lactone substituents were determined on the basis of the vicinal (3)JHH coupling value. Due to the presence of the β-lactone, 1 and 2 were evaluated for their ability to inhibit the human 20S proteasome. 1 and 2 both inhibited the 20S proteasome in vitro with IC50 values of 0.35 and 0.93 μM, respectively.
Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, ... more Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, solely produced by animals, is the main structural protein of hair (mainly alpha keratin), skin and feathers (mainly beta keratin). It has a high stability and observes a slow biodegradation. This study focuses on the identification of a keratinase being highly specific for hair and skin keratin. Thus, an application might be to soften/remove hair and as active ingredient in anti-aging products to reduce wrinkles. Therefore, environmental samples as well as known bacteria strains are screened for their keratin biodegradation potential by using modified hair as a nutrient that releases colored degradation products. This allows to photometrically screening a large number of setups for keratin degradation. Promising setups are then further characterized regarding the responsible organism(s), the activity of the keratinase, and the feasibility of the organism/enzyme for its potential applica...
The natural products community has been investigating secondary metabolites from marine fungi for... more The natural products community has been investigating secondary metabolites from marine fungi for several decades, but when one attempts to search for validated reports of new natural products from marine fungi, one encounters a literature saturated with reports from 'marine-derived' fungi. Of the 1000+ metabolites that have been characterized to date, only approximately 80 of these have been isolated from species from exclusively marine lineages. These metabolites are summarized here along with the lifestyle and habitats of their producing organisms. Furthermore, we address some of the reasons for the apparent disconnect between the stated objectives of discovering new chemistry from marine organisms and the apparent neglect of the truly exceptional obligate marine fungi. We also offer suggestions on how to reinvigorate enthusiasm for marine natural products discovery from fungi from exclusive marine lineages and highlight the need for critically assessing the role of appar...
A method was developed to distinguish Vaccinium species based on leaf extracts using nuclear magn... more A method was developed to distinguish Vaccinium species based on leaf extracts using nuclear magnetic resonance spectroscopy. Reference spectra were measured on leaf extracts from several species, including lowbush blueberry (Vaccinium angustifolium), oval leaf huckleberry (Vaccinium ovalifolium), and cranberry (Vaccinium macrocarpon). Using principal component analysis, these leaf extracts were resolved in the scores plot. Analysis of variance statistical tests demonstrated that the three groups differ significantly on PC2, establishing that the three species can be distinguished by nuclear magnetic resonance. Soft independent modeling of class analogies models for each species also showed discrimination between species. To demonstrate the robustness of nuclear magnetic resonance spectroscopy for botanical identification, spectra of a sample of lowbush blueberry leaf extract were measured at five different sites, with different field strengths (600 versus 700 MHz), different probe types (cryogenic versus room temperature probes), different sample diameters (1.7 mm versus 5 mm), and different consoles (Avance I versus Avance III). Each laboratory independently demonstrated the linearity of their NMR measurements by acquiring a standard curve for chlorogenic acid (R(2) = 0.9782 to 0.9998). Spectra acquired on different spectrometers at different sites classifed into the expected group for the Vaccinium spp., confirming the utility of the method to distinguish Vaccinium species and demonstrating nuclear magnetic resonance fingerprinting for material validation of a natural health product.
Pseudopterogorgia elisabethae is a common inhabitant of Caribbean reefs and is a well-known sourc... more Pseudopterogorgia elisabethae is a common inhabitant of Caribbean reefs and is a well-known source of diterpenes with diverse biological activities. Notably, this octocoral is the sole source of the pseudopterosin family of anti-inflammatory diterpenes and is harvested to supply commercial demand for these metabolites. We have characterized the composition of the bacterial community associated with P. elisabethae collected from Providencia Island, Colombia, using both culture-dependent and culture-independent approaches. Culture-independent analysis revealed that the bacterial communities were composed of eight phyla, of which Proteobacteria was the most abundant. At the class level, bacterial communities were dominated by Gammaproteobacteria (82-87Â %). Additionally, operational taxonomic units related to Pseudomonas and Endozoicomonas species were the most abundant phylotypes consistently associated with P. elisabethae colonies. Culture-dependent analysis resulted in the identification of 40 distinct bacteria classified as Bacilli (15), Actinobacteria (12), Gammaproteobacteria (9), Alphaproteobacteria (3), and Betaproteobacteria (1). Only one of the 40 cultured bacteria was closely related to a dominant phylotype detected in the culture-independent study, suggesting that conventional culturing techniques failed to culture the majority of octocoral-associated bacterial diversity. To the best of our knowledge, this is the first characterization of the bacterial diversity associated with P. elisabethae.
Four new steroidal glycosides, acanthifoliosides G-J (1-4), were isolated as minor constituents f... more Four new steroidal glycosides, acanthifoliosides G-J (1-4), were isolated as minor constituents from the Caribbean marine sponge Pandaros acanthifolium. These metabolites are characterized by a highly oxygenated D ring and the presence of a disaccharide rhamnose-glucose residue and a rhamnose at positions C-3 and C-15, respectively. Their structures were established on the basis of extensive interpretation of 1D and 2D NMR data and HRESIMS analyses. The absolute configurations of the glucose and rhamnose sugars were determined by preparing aldose o-tolylthiocarbamate derivatives and comparison to authentic standards by LC/HRESIMS. Acanthifolioside G (1) exhibited antioxidant and cytoprotective activities.
A screening of marine bacteria for antimicrobial activity resulted in the isolation of Bacillus p... more A screening of marine bacteria for antimicrobial activity resulted in the isolation of Bacillus pumilus (SP21) from a sediment sample collected in the Bahamas. A bioassay-guided fractionation led to the isolation of five surfactin analogs, glycocholic acid, amicoumacins A and B in addition to three new compounds named lipoamides A-C. The chemical structure of all the bioactive compounds was elucidated using spectroscopic methods including 2D NMR and MS. The antimicrobial activity of each compound was evaluated against a panel of pathogens and is reported herein.
We report here the draft genome sequence of Kitasatospora griseola strain MF730-N6, a known produ... more We report here the draft genome sequence of Kitasatospora griseola strain MF730-N6, a known producer of bafilomycin, terpentecin, and satosporins. The current assembly comprises 8 contigs covering 7.97 Mb. Genome annotation revealed 7,225 protein coding sequences, 100 tRNAs, 40 rRNA genes, and 23 secondary metabolite biosynthetic gene clusters.
Melanoma causes the highest rate of skin cancer related fatalities. If detected and treated early... more Melanoma causes the highest rate of skin cancer related fatalities. If detected and treated early, melanoma is mostly curable. Unfortunately, once metastasis has occurred melanoma is often fatal. The biochemical pathways involved in the development from primary to metastatic melanoma is an area under intense investigation. A high-throughput proteomics approach has been applied to better understand the processes that underlie tumor formation and progression. Analyses of global melanoma proteome expression patterns are compared between the primary melanoma cell line WM-115 and the metastatic melanoma cell line WM-266-4, where both cell lines derived from the same patient. Total cell lysates were separated by two dimensional-gel electrophoresis (2DE). After protein differential expression analysis, protein spots of interest were excised, digested with trypsin and analyzed by LC-MS/MS. The mass data were searched against an in-house NCBInr database using the Mascot search engine for pro...
Two novel β-lactone-containing natural products, cystargolides A (1) and B (2), were isolated fro... more Two novel β-lactone-containing natural products, cystargolides A (1) and B (2), were isolated from the actinomycete Kitasatospora cystarginea. The production of these two natural products was highlighted using a methodology associating liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis and the statistical analysis tool principal component analysis (PCA). Their structures were elucidated by interpretation of NMR experiments and tandem mass spectrometry. The absolute configurations of the amino acid residues were determined using Marfey's method, and the relative configurations of the β-lactone substituents were determined on the basis of the vicinal (3)JHH coupling value. Due to the presence of the β-lactone, 1 and 2 were evaluated for their ability to inhibit the human 20S proteasome. 1 and 2 both inhibited the 20S proteasome in vitro with IC50 values of 0.35 and 0.93 μM, respectively.
Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, ... more Keratinases are enzymes that have the ability to degrade the insoluble protein keratin. Keratin, solely produced by animals, is the main structural protein of hair (mainly alpha keratin), skin and feathers (mainly beta keratin). It has a high stability and observes a slow biodegradation. This study focuses on the identification of a keratinase being highly specific for hair and skin keratin. Thus, an application might be to soften/remove hair and as active ingredient in anti-aging products to reduce wrinkles. Therefore, environmental samples as well as known bacteria strains are screened for their keratin biodegradation potential by using modified hair as a nutrient that releases colored degradation products. This allows to photometrically screening a large number of setups for keratin degradation. Promising setups are then further characterized regarding the responsible organism(s), the activity of the keratinase, and the feasibility of the organism/enzyme for its potential applica...
The natural products community has been investigating secondary metabolites from marine fungi for... more The natural products community has been investigating secondary metabolites from marine fungi for several decades, but when one attempts to search for validated reports of new natural products from marine fungi, one encounters a literature saturated with reports from 'marine-derived' fungi. Of the 1000+ metabolites that have been characterized to date, only approximately 80 of these have been isolated from species from exclusively marine lineages. These metabolites are summarized here along with the lifestyle and habitats of their producing organisms. Furthermore, we address some of the reasons for the apparent disconnect between the stated objectives of discovering new chemistry from marine organisms and the apparent neglect of the truly exceptional obligate marine fungi. We also offer suggestions on how to reinvigorate enthusiasm for marine natural products discovery from fungi from exclusive marine lineages and highlight the need for critically assessing the role of appar...
A method was developed to distinguish Vaccinium species based on leaf extracts using nuclear magn... more A method was developed to distinguish Vaccinium species based on leaf extracts using nuclear magnetic resonance spectroscopy. Reference spectra were measured on leaf extracts from several species, including lowbush blueberry (Vaccinium angustifolium), oval leaf huckleberry (Vaccinium ovalifolium), and cranberry (Vaccinium macrocarpon). Using principal component analysis, these leaf extracts were resolved in the scores plot. Analysis of variance statistical tests demonstrated that the three groups differ significantly on PC2, establishing that the three species can be distinguished by nuclear magnetic resonance. Soft independent modeling of class analogies models for each species also showed discrimination between species. To demonstrate the robustness of nuclear magnetic resonance spectroscopy for botanical identification, spectra of a sample of lowbush blueberry leaf extract were measured at five different sites, with different field strengths (600 versus 700 MHz), different probe types (cryogenic versus room temperature probes), different sample diameters (1.7 mm versus 5 mm), and different consoles (Avance I versus Avance III). Each laboratory independently demonstrated the linearity of their NMR measurements by acquiring a standard curve for chlorogenic acid (R(2) = 0.9782 to 0.9998). Spectra acquired on different spectrometers at different sites classifed into the expected group for the Vaccinium spp., confirming the utility of the method to distinguish Vaccinium species and demonstrating nuclear magnetic resonance fingerprinting for material validation of a natural health product.
Pseudopterogorgia elisabethae is a common inhabitant of Caribbean reefs and is a well-known sourc... more Pseudopterogorgia elisabethae is a common inhabitant of Caribbean reefs and is a well-known source of diterpenes with diverse biological activities. Notably, this octocoral is the sole source of the pseudopterosin family of anti-inflammatory diterpenes and is harvested to supply commercial demand for these metabolites. We have characterized the composition of the bacterial community associated with P. elisabethae collected from Providencia Island, Colombia, using both culture-dependent and culture-independent approaches. Culture-independent analysis revealed that the bacterial communities were composed of eight phyla, of which Proteobacteria was the most abundant. At the class level, bacterial communities were dominated by Gammaproteobacteria (82-87Â %). Additionally, operational taxonomic units related to Pseudomonas and Endozoicomonas species were the most abundant phylotypes consistently associated with P. elisabethae colonies. Culture-dependent analysis resulted in the identification of 40 distinct bacteria classified as Bacilli (15), Actinobacteria (12), Gammaproteobacteria (9), Alphaproteobacteria (3), and Betaproteobacteria (1). Only one of the 40 cultured bacteria was closely related to a dominant phylotype detected in the culture-independent study, suggesting that conventional culturing techniques failed to culture the majority of octocoral-associated bacterial diversity. To the best of our knowledge, this is the first characterization of the bacterial diversity associated with P. elisabethae.
Four new steroidal glycosides, acanthifoliosides G-J (1-4), were isolated as minor constituents f... more Four new steroidal glycosides, acanthifoliosides G-J (1-4), were isolated as minor constituents from the Caribbean marine sponge Pandaros acanthifolium. These metabolites are characterized by a highly oxygenated D ring and the presence of a disaccharide rhamnose-glucose residue and a rhamnose at positions C-3 and C-15, respectively. Their structures were established on the basis of extensive interpretation of 1D and 2D NMR data and HRESIMS analyses. The absolute configurations of the glucose and rhamnose sugars were determined by preparing aldose o-tolylthiocarbamate derivatives and comparison to authentic standards by LC/HRESIMS. Acanthifolioside G (1) exhibited antioxidant and cytoprotective activities.
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Papers by Russell Kerr