International Biodeterioration & Biodegradation, Sep 1, 2011
Here, we report on the biodegradation of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-... more Here, we report on the biodegradation of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] by a novel thermoalkanophilic extracellular esterase from the soil isolate Streptomyces sp. IN1. Preliminary screening and isolation of the bacterium was done using polyhydroxyalkanoate latex medium (PHALM). The isolate was cultured with P(3HB-co-3HV) as the only carbon source and by-products of degradation were derivatized with [N,O-bis(trimethylsilyl)trifluroacetamide] (BSTFA). These products were identified by gas chromatography/mass spectrometry (GC–MS) as silylated hydroxybutyric acid (3HB) and hydroxyvaleric acid, suggesting extracellular depolymerase activity by the isolate. The depolymerase was isolated by (NH4)2SO4 fractionation, dialyzed and purified using fast protein liquid chromatography (FPLC), and confirmed using P(3HB-co-3HV) as a sole source of carbon. The molecular mass of the FPLC purified enzyme occurred between 45 and 66 kDa (SDS–PAGE), but was confirmed by matrix assisted laser desorption ionization–time of flight mass spectrometry (MALDI–TOF MS) to be 62 kDa. Enzyme activity was significantly inhibited by phenylmethylsulfonyl fluoride (PMSF), dithiothreitol (DTT), and Tween 80, but induced by azide (N3−). Sensitivity to PMSF, DTT, and Tween 80 suggests the involvement of serine as an active site amino acid with disulphide bonds contributing to the catalytic activity, as well as the presence of hydrophobic regions in the enzyme. Non-inhibition of activity by azide indicates that metal ions may not be required as cofactors for activity. This observation was further corroborated by the decrease in enzyme activity in the presence of metal ions such as Ca2+, Mg2+, Na+, and K+. The kinetic parameters, Vmax and Km, in the presence of p-nitrophenylbutyrate as substrate, were determined to be 5.06 × 10−1 μmol min−1 and 6.73 × 10−1 mM, respectively.
International Journal of Current Science Research and Review
Stenotrophomonas maltophilia is a commensal and an emerging pathogen earlier noted in broad-spect... more Stenotrophomonas maltophilia is a commensal and an emerging pathogen earlier noted in broad-spectrum life-threatening infections among the vulnerable, but more recently as a pathogen in immunocompetent individuals. In the current study, S. maltophilia was identified from 78% of vegetable samples. Bacterial population count ranged from 5.50 × 10-1to 4.3 × 10-4 cfu/g (mean 8.9 × 105 cfu/g, median 7.75 × 103 cfu/g). Based on a cross-sectional study performed during 2015-2016 n=35 and 2016-2017 n=55 S. maltophilia was isolated from clinical samples. The occurrence of S. maltophilia from clinical samples increased during 2016-2017 with a significant value of P=.0008. Out of the total of n=90 S. maltophilia, clinical isolates (35.28%) were from tracheal aspirates, followed by cerebrospinal fluid (CSF) (17.70%), sputum (15.20%), blood (16.82%), and urine (15.0%). Sample sources were taken from different age groups of patients between 0-75 years. Almost all the isolates > 97% confirmed m...
The synthetic gene probe is a 20 mer oligonucleotide, derived from listeriolysin O gene sequence ... more The synthetic gene probe is a 20 mer oligonucleotide, derived from listeriolysin O gene sequence of Listeria monocytogenes and shown to be specific for strains of this organism. This probe was used in a DNA-colony hybridization assay to evaluate its suitability in detecting (β-hemolytic L. monocytogenes in ground beef. Thirty-six ground beef samples were plated onto three media: Trypticase soy agar with 0.6% yeast extract, lithium chloride-phenylethanol-moxalactam agar and Martin's agar, both directly and after selective enrichment in Food and Drug Administration broth. Of the 118 gram-positive and catalase-positive isolates selected from the plates, only 24 gave detectable hybridization signal with the probe. CAMP-test and standard biochemical tests also revealed that only these 24 probe positive isolates were (β-hemolytic L. monocytogenes. Of the 36 samples of ground beef, 6 were positive for Listeria spp., out of which 4 were L. monocytogenes.
Journal of Industrial Microbiology and Biotechnology, 1998
Saponified vernonia oil was converted exclusively to poly(β-hydroxybutyrate) (PHB) by Alcaligen... more Saponified vernonia oil was converted exclusively to poly(β-hydroxybutyrate) (PHB) by Alcaligenes eutrophus in a single-stage batch culture. After harvesting, centrifugation followed by lyophilization, the resulting dried cells contained up to 42.8 wt% PHB having a peak molecular mass of 381 863 Da, weight-average molecular mass of 308 390 Da, and a polydispersity of 1.1. The PHB had a melting point (Tm) range of 163–174°C
Abstract A total of 1535 bacterial isolates were examined from 29 retail samples of ground beef w... more Abstract A total of 1535 bacterial isolates were examined from 29 retail samples of ground beef when fresh and after aerobic spoilage at 5–7°C. Of these, 1354 (88%) were gram-negative and oxidase-positive, but only 34 were identified by API 20E as Moraxella -26 from fresh and eight from spoiled samples. Ninety-five percent of the oxidase-positive isolates were Pseudomonas spp. and 66% of these were recovered from the meats after spoilage. The findings bring into question the widely-held view that moraxellae along with Acinetobacter are rather abundant in ground beef.
Cronobacter sakazakii is a food-borne pathogenic bacterium that may cause severe illness in neona... more Cronobacter sakazakii is a food-borne pathogenic bacterium that may cause severe illness in neonates and the elderly. We present the genome sequence of a rare strain (ST40, CC45), commonly found in multiple food processing facilities and in powdered infant formula and only indicted in a single clinical case.
Lactic acid bacteria are a major component of dairy products, especially species belonging to the... more Lactic acid bacteria are a major component of dairy products, especially species belonging to the genus Lactobacillus . This study reports the whole-genome sequence of Schleiferilactobacillus harbinensis isolated from laban , indigenous fermented milk of Saudi Arabia. The genome sequence is 3,023,618 bp long, has 179 contigs, and has a G+C content of 53.3%.
Kitfo is a version of beef tartar widely consumed in the Ethiopian community. It is made from raw... more Kitfo is a version of beef tartar widely consumed in the Ethiopian community. It is made from raw minced beef and a blend of powdered spice and butter. Although previous studies have shown that kitfo contains several bacteria that are of public health concern, the status of their antibiotic resistance is not known. In this study, the antibiotic resistance of bacterial isolates from twenty-six retail kitfo samples obtained from the Metropolitan Washington area was analyzed. Characterization and antibiotic sensitivity of the isolates were determined by the VITEK 2 system, while Pulsed-field gel electrophoresis (PFGE) was used to delineate the intraspecies variations. Fifty-nine percent of the isolates were resistant to two or more antibiotics. Acinetobacter calcoaceticus and Pseudomonas luteola were multidrug-resistant to the classes of beta-lactam, cephalosporins, and nitrofurantoin. The antibiotic susceptibility profile of the isolates were: cefazolin (59%), cefoxitin (50%), ampicil...
Journal of microbiology, biotechnology and food sciences, 2019
A new strain of Lactobacillus parafarraginis was isolated from a sample of commercial yogurt and ... more A new strain of Lactobacillus parafarraginis was isolated from a sample of commercial yogurt and identified by phenotypic and molecular methods. Phenotypic characterization showed bacilli sizes ~ 0.75-2.75 μm × 0.25-0.75 μm, a generation time of ~3.04 h under anaerobic conditions, halotolerance, lactose fermentation, production of hydrogen sulfide gas from Kliger iron agar, and the presence of an unusual fatty-acid methyl ester, cis- 10-nonadecenoic acid. Based on 16S rRNA gene sequencing, the isolate was identified as Lactobacillus parafarraginis and given the GenBank accession number (KU495926). L. parafarraginis ((KU495926)) inhibited 14 multidrug-resistant (MDR) and extended spectrum β-lactamase (ESBL) Gram-negative clinical isolates, as well as 11 other pathogens by spot-test and well-diffusion assays. The MDR/ESBL clinical isolates and other pathogens included Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii/haemolyticus, Enterobacter aerogenes, Proteus mirabi...
International Biodeterioration & Biodegradation, Sep 1, 2011
Here, we report on the biodegradation of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-... more Here, we report on the biodegradation of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] by a novel thermoalkanophilic extracellular esterase from the soil isolate Streptomyces sp. IN1. Preliminary screening and isolation of the bacterium was done using polyhydroxyalkanoate latex medium (PHALM). The isolate was cultured with P(3HB-co-3HV) as the only carbon source and by-products of degradation were derivatized with [N,O-bis(trimethylsilyl)trifluroacetamide] (BSTFA). These products were identified by gas chromatography/mass spectrometry (GC–MS) as silylated hydroxybutyric acid (3HB) and hydroxyvaleric acid, suggesting extracellular depolymerase activity by the isolate. The depolymerase was isolated by (NH4)2SO4 fractionation, dialyzed and purified using fast protein liquid chromatography (FPLC), and confirmed using P(3HB-co-3HV) as a sole source of carbon. The molecular mass of the FPLC purified enzyme occurred between 45 and 66 kDa (SDS–PAGE), but was confirmed by matrix assisted laser desorption ionization–time of flight mass spectrometry (MALDI–TOF MS) to be 62 kDa. Enzyme activity was significantly inhibited by phenylmethylsulfonyl fluoride (PMSF), dithiothreitol (DTT), and Tween 80, but induced by azide (N3−). Sensitivity to PMSF, DTT, and Tween 80 suggests the involvement of serine as an active site amino acid with disulphide bonds contributing to the catalytic activity, as well as the presence of hydrophobic regions in the enzyme. Non-inhibition of activity by azide indicates that metal ions may not be required as cofactors for activity. This observation was further corroborated by the decrease in enzyme activity in the presence of metal ions such as Ca2+, Mg2+, Na+, and K+. The kinetic parameters, Vmax and Km, in the presence of p-nitrophenylbutyrate as substrate, were determined to be 5.06 × 10−1 μmol min−1 and 6.73 × 10−1 mM, respectively.
International Journal of Current Science Research and Review
Stenotrophomonas maltophilia is a commensal and an emerging pathogen earlier noted in broad-spect... more Stenotrophomonas maltophilia is a commensal and an emerging pathogen earlier noted in broad-spectrum life-threatening infections among the vulnerable, but more recently as a pathogen in immunocompetent individuals. In the current study, S. maltophilia was identified from 78% of vegetable samples. Bacterial population count ranged from 5.50 × 10-1to 4.3 × 10-4 cfu/g (mean 8.9 × 105 cfu/g, median 7.75 × 103 cfu/g). Based on a cross-sectional study performed during 2015-2016 n=35 and 2016-2017 n=55 S. maltophilia was isolated from clinical samples. The occurrence of S. maltophilia from clinical samples increased during 2016-2017 with a significant value of P=.0008. Out of the total of n=90 S. maltophilia, clinical isolates (35.28%) were from tracheal aspirates, followed by cerebrospinal fluid (CSF) (17.70%), sputum (15.20%), blood (16.82%), and urine (15.0%). Sample sources were taken from different age groups of patients between 0-75 years. Almost all the isolates > 97% confirmed m...
The synthetic gene probe is a 20 mer oligonucleotide, derived from listeriolysin O gene sequence ... more The synthetic gene probe is a 20 mer oligonucleotide, derived from listeriolysin O gene sequence of Listeria monocytogenes and shown to be specific for strains of this organism. This probe was used in a DNA-colony hybridization assay to evaluate its suitability in detecting (β-hemolytic L. monocytogenes in ground beef. Thirty-six ground beef samples were plated onto three media: Trypticase soy agar with 0.6% yeast extract, lithium chloride-phenylethanol-moxalactam agar and Martin's agar, both directly and after selective enrichment in Food and Drug Administration broth. Of the 118 gram-positive and catalase-positive isolates selected from the plates, only 24 gave detectable hybridization signal with the probe. CAMP-test and standard biochemical tests also revealed that only these 24 probe positive isolates were (β-hemolytic L. monocytogenes. Of the 36 samples of ground beef, 6 were positive for Listeria spp., out of which 4 were L. monocytogenes.
Journal of Industrial Microbiology and Biotechnology, 1998
Saponified vernonia oil was converted exclusively to poly(β-hydroxybutyrate) (PHB) by Alcaligen... more Saponified vernonia oil was converted exclusively to poly(β-hydroxybutyrate) (PHB) by Alcaligenes eutrophus in a single-stage batch culture. After harvesting, centrifugation followed by lyophilization, the resulting dried cells contained up to 42.8 wt% PHB having a peak molecular mass of 381 863 Da, weight-average molecular mass of 308 390 Da, and a polydispersity of 1.1. The PHB had a melting point (Tm) range of 163–174°C
Abstract A total of 1535 bacterial isolates were examined from 29 retail samples of ground beef w... more Abstract A total of 1535 bacterial isolates were examined from 29 retail samples of ground beef when fresh and after aerobic spoilage at 5–7°C. Of these, 1354 (88%) were gram-negative and oxidase-positive, but only 34 were identified by API 20E as Moraxella -26 from fresh and eight from spoiled samples. Ninety-five percent of the oxidase-positive isolates were Pseudomonas spp. and 66% of these were recovered from the meats after spoilage. The findings bring into question the widely-held view that moraxellae along with Acinetobacter are rather abundant in ground beef.
Cronobacter sakazakii is a food-borne pathogenic bacterium that may cause severe illness in neona... more Cronobacter sakazakii is a food-borne pathogenic bacterium that may cause severe illness in neonates and the elderly. We present the genome sequence of a rare strain (ST40, CC45), commonly found in multiple food processing facilities and in powdered infant formula and only indicted in a single clinical case.
Lactic acid bacteria are a major component of dairy products, especially species belonging to the... more Lactic acid bacteria are a major component of dairy products, especially species belonging to the genus Lactobacillus . This study reports the whole-genome sequence of Schleiferilactobacillus harbinensis isolated from laban , indigenous fermented milk of Saudi Arabia. The genome sequence is 3,023,618 bp long, has 179 contigs, and has a G+C content of 53.3%.
Kitfo is a version of beef tartar widely consumed in the Ethiopian community. It is made from raw... more Kitfo is a version of beef tartar widely consumed in the Ethiopian community. It is made from raw minced beef and a blend of powdered spice and butter. Although previous studies have shown that kitfo contains several bacteria that are of public health concern, the status of their antibiotic resistance is not known. In this study, the antibiotic resistance of bacterial isolates from twenty-six retail kitfo samples obtained from the Metropolitan Washington area was analyzed. Characterization and antibiotic sensitivity of the isolates were determined by the VITEK 2 system, while Pulsed-field gel electrophoresis (PFGE) was used to delineate the intraspecies variations. Fifty-nine percent of the isolates were resistant to two or more antibiotics. Acinetobacter calcoaceticus and Pseudomonas luteola were multidrug-resistant to the classes of beta-lactam, cephalosporins, and nitrofurantoin. The antibiotic susceptibility profile of the isolates were: cefazolin (59%), cefoxitin (50%), ampicil...
Journal of microbiology, biotechnology and food sciences, 2019
A new strain of Lactobacillus parafarraginis was isolated from a sample of commercial yogurt and ... more A new strain of Lactobacillus parafarraginis was isolated from a sample of commercial yogurt and identified by phenotypic and molecular methods. Phenotypic characterization showed bacilli sizes ~ 0.75-2.75 μm × 0.25-0.75 μm, a generation time of ~3.04 h under anaerobic conditions, halotolerance, lactose fermentation, production of hydrogen sulfide gas from Kliger iron agar, and the presence of an unusual fatty-acid methyl ester, cis- 10-nonadecenoic acid. Based on 16S rRNA gene sequencing, the isolate was identified as Lactobacillus parafarraginis and given the GenBank accession number (KU495926). L. parafarraginis ((KU495926)) inhibited 14 multidrug-resistant (MDR) and extended spectrum β-lactamase (ESBL) Gram-negative clinical isolates, as well as 11 other pathogens by spot-test and well-diffusion assays. The MDR/ESBL clinical isolates and other pathogens included Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii/haemolyticus, Enterobacter aerogenes, Proteus mirabi...
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Papers by Broderick Eribo