Aims: To examine predominant isolates of Bacillus subtilis and B. pumilus isolated from Soumbala... more Aims: To examine predominant isolates of Bacillus subtilis and B. pumilus isolated from Soumbala for their antimicrobial activity against indicator microorganisms as Micrococcus luteus, Staphyloccocusaureus, Bacillus cereus, Enterococus facium, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Shigella dysenteriae, Yersinia enterocolitica, Aspergillus ochraceus and Penicillium roqueforti.Methods and Results: Growth inhibition of indicator microorganisms by cells and supernatants of three B. subtilis and two B. pumilus strains was investigated using agar diffusion tests. Inactivation of indicator microorganisms was investigated in laboratory broth and during the fermentation of African locust bean for Soumbala production. The Bacillus isolates showed variable ability of inhibition and inactivation according to the indicator microorganism. The supernatants of pure cultures of B. subtilis inhibited one strain of B. cereus, one of Staph. aureus and E. coli and caused abnormal germination of Aspergillus ochraceus. The supernatant of mixed cultures of B. subtilis and indicators inhibited all the indicators. A treatment with protease eliminated the inhibitions. Isolates of B. subtilis inactivated all the indicators organisms during the fermentation of African locust bean as well as in laboratory broth with about five to eight decimal reduction.Conclusion: Bacillus isolates from Soumbala inhibit and inactivate Gram-positive and Gram-negative bacteria as well as ochratoxin A producing fungi during both laboratory cultivation and natural fermentation.Significance and Impact of the Study: Selection of starter cultures of Bacillus spp. for controlled production of Soumbala.
Aim: To study genotypic diversity of isolates of Brochothrix thermosphacta recovered from meat, ... more Aim: To study genotypic diversity of isolates of Brochothrix thermosphacta recovered from meat, poultry and fish.Methods and Results: A total of 27 bacteria isolated from 19 samples of meat, poultry and fish were identified phenotypically and genotypically using PCR amplification of 16S-23S rDNA intergenic transcribed spacer (ITS-PCR), repetitive sequence-based PCR (rep-PCR) and 16S rDNA sequencing. Using ITS-PCR, all bacteria showed the same DNA profile as the reference strains of Br. thermosphacta, allowing typing of the isolates at species level. Using 16S rDNA sequencing, all isolates were identified, at genus and species level, as Br. thermosphacta. Identification as Br. campestris was observed with a lower, but very close, level of similarity. Rep-PCR was more discriminatory than ITS-PCR and allowed differentiation of four subgroups among the isolates.Conclusion: Minor genotypic differences among Br. thermosphacta strains from meat, poultry and fish were observed.Significance and Impact of the Study: A rudimentary exploration of genotypic differences of Br. thermosphacta from meat, poultry and fish resulted in preliminary confirmation of the suitability of ITS-PCR for typing Br. thermosphacta and confirmed the value of rep-PCR fingerprinting to discriminate between Br. thermosphacta strains.
Sixteen spore forming Gram-positive bacteria were isolated from the rock of an oil reservoir loca... more Sixteen spore forming Gram-positive bacteria were isolated from the rock of an oil reservoir located in a deep-water production basin in Brazil. These strains were identified as belonging to the genus Bacillus using classical biochemical techniques and API 50CH kits, and their identity was confirmed by sequencing of part of the 16S rRNA gene. All strains were tested for oil degradation ability in microplates using Arabian Light and Marlin oils and only seven strains showed positive results in both kinds of oils. They were also able to grow in the presence of carbazole, n-hexadecane and polyalphaolefin (PAO), but not in toluene, as the only carbon sources. The production of key enzymes involved with aromatic hydrocarbons biodegradation process by Bacillus strains (catechol 1,2-dioxygenase and catechol 2,3-dioxygenase) was verified spectrophotometrically by detection of cis,cis-muconic acid and 2-hydroxymuconic semialdehyde, and results indicated that the ortho ring cleavage pathway is preferential. Furthermore, polymerase chain reaction (PCR) products were obtained when the DNA of seven Bacillus strains were screened for the presence of catabolic genes encoding alkane monooxygenase, catechol 1,2-dioxygenase, and/or catechol 2,3-dioxygenase. This is the first study on Bacillus strains isolated from an oil reservoir in Brazil.
Aims: To identify Bacillus spp. responsible of the fermentation of Hibiscus sabdariffa for produ... more Aims: To identify Bacillus spp. responsible of the fermentation of Hibiscus sabdariffa for production of Bikalga, an alkaline fermented food used as a condiment in Burkina Faso.Methods and Results: Seventy bacteria were isolated from Bikalga produced in different regions of Burkina Faso and identified by phenotyping and genotyping using PCR amplification of the 16S-23S rDNA intergenic transcribed spacer (ITS-PCR), repetitive sequence-based PCR (rep-PCR) and DNA sequencing. The isolates were characterized as motile, rod-shaped, endospore forming, catalase positive, Gram-positive bacteria. ITS-PCR allowed typing mainly at species level. Rep-PCR was more discriminative and allowed a typing at ssp. level. The DNA sequencing combined with the Blast search program and fermentation profiles using API 50CHB system allowed an identification of the bacteria as Bacillus subtilis, B. licheniformis, B. cereus, B. pumilus, B. badius, Brevibacillus bortelensis, B. sphaericus and B. fusiformis. B. subtilis were the predominant bacterium (42) followed by B. licheniformis (16).Conclusions: Various species and ssp. of Bacillus are involved in fermentation of H. sabdariffa for production of Bikalga.Significance and Impact of the study: Selection of starter cultures of Bacillus for controlled production of Bikalga, selection of probiotic bacteria.
Bacillus spp. are the predominant microorganisms in fermented African locust bean called Soumbala... more Bacillus spp. are the predominant microorganisms in fermented African locust bean called Soumbala in Burkina Faso. Ten strains selected as potential starter cultures were characterised by PCR amplification of the16S-23S rDNA intergenic transcribed spacer (ITS-PCR), restriction fragment length polymorphism of the ITS-PCR (ITS-PCR RFLP), pulsed field gel electrophoresis (PFGE) and sequencing of the 968-1401 region of the 16S rDNA. In previous studies, the isolates were identified by phenotyping as Bacillus subtilis and Bacillus pumilus. The phenotyping was repeated as a reference in the present study. The ITS-PCR and ITS-PCR RLFP allowed a typing at species level. The PFGE was more discriminative and allowed a typing at strain level. Full agreement with the phenotyping was observed in all cases. The sequencing of the 16S rDNA allowed the identification at species level with an identity from 97% to 100% comparing the sequences to those from the GenBank databases. The desired cultures of B. subtilis and B. pumilus from African locust bean fermentation were distinguished by ITS-PCR and ITS-PCR RLFP from Bacillus cereus and Bacillus sphaericus which sometimes occur in the beginning of the fermentation.
Aims: To examine predominant isolates of Bacillus subtilis and B. pumilus isolated from Soumbala... more Aims: To examine predominant isolates of Bacillus subtilis and B. pumilus isolated from Soumbala for their antimicrobial activity against indicator microorganisms as Micrococcus luteus, Staphyloccocusaureus, Bacillus cereus, Enterococus facium, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Shigella dysenteriae, Yersinia enterocolitica, Aspergillus ochraceus and Penicillium roqueforti.Methods and Results: Growth inhibition of indicator microorganisms by cells and supernatants of three B. subtilis and two B. pumilus strains was investigated using agar diffusion tests. Inactivation of indicator microorganisms was investigated in laboratory broth and during the fermentation of African locust bean for Soumbala production. The Bacillus isolates showed variable ability of inhibition and inactivation according to the indicator microorganism. The supernatants of pure cultures of B. subtilis inhibited one strain of B. cereus, one of Staph. aureus and E. coli and caused abnormal germination of Aspergillus ochraceus. The supernatant of mixed cultures of B. subtilis and indicators inhibited all the indicators. A treatment with protease eliminated the inhibitions. Isolates of B. subtilis inactivated all the indicators organisms during the fermentation of African locust bean as well as in laboratory broth with about five to eight decimal reduction.Conclusion: Bacillus isolates from Soumbala inhibit and inactivate Gram-positive and Gram-negative bacteria as well as ochratoxin A producing fungi during both laboratory cultivation and natural fermentation.Significance and Impact of the Study: Selection of starter cultures of Bacillus spp. for controlled production of Soumbala.
Aim: To study genotypic diversity of isolates of Brochothrix thermosphacta recovered from meat, ... more Aim: To study genotypic diversity of isolates of Brochothrix thermosphacta recovered from meat, poultry and fish.Methods and Results: A total of 27 bacteria isolated from 19 samples of meat, poultry and fish were identified phenotypically and genotypically using PCR amplification of 16S-23S rDNA intergenic transcribed spacer (ITS-PCR), repetitive sequence-based PCR (rep-PCR) and 16S rDNA sequencing. Using ITS-PCR, all bacteria showed the same DNA profile as the reference strains of Br. thermosphacta, allowing typing of the isolates at species level. Using 16S rDNA sequencing, all isolates were identified, at genus and species level, as Br. thermosphacta. Identification as Br. campestris was observed with a lower, but very close, level of similarity. Rep-PCR was more discriminatory than ITS-PCR and allowed differentiation of four subgroups among the isolates.Conclusion: Minor genotypic differences among Br. thermosphacta strains from meat, poultry and fish were observed.Significance and Impact of the Study: A rudimentary exploration of genotypic differences of Br. thermosphacta from meat, poultry and fish resulted in preliminary confirmation of the suitability of ITS-PCR for typing Br. thermosphacta and confirmed the value of rep-PCR fingerprinting to discriminate between Br. thermosphacta strains.
Sixteen spore forming Gram-positive bacteria were isolated from the rock of an oil reservoir loca... more Sixteen spore forming Gram-positive bacteria were isolated from the rock of an oil reservoir located in a deep-water production basin in Brazil. These strains were identified as belonging to the genus Bacillus using classical biochemical techniques and API 50CH kits, and their identity was confirmed by sequencing of part of the 16S rRNA gene. All strains were tested for oil degradation ability in microplates using Arabian Light and Marlin oils and only seven strains showed positive results in both kinds of oils. They were also able to grow in the presence of carbazole, n-hexadecane and polyalphaolefin (PAO), but not in toluene, as the only carbon sources. The production of key enzymes involved with aromatic hydrocarbons biodegradation process by Bacillus strains (catechol 1,2-dioxygenase and catechol 2,3-dioxygenase) was verified spectrophotometrically by detection of cis,cis-muconic acid and 2-hydroxymuconic semialdehyde, and results indicated that the ortho ring cleavage pathway is preferential. Furthermore, polymerase chain reaction (PCR) products were obtained when the DNA of seven Bacillus strains were screened for the presence of catabolic genes encoding alkane monooxygenase, catechol 1,2-dioxygenase, and/or catechol 2,3-dioxygenase. This is the first study on Bacillus strains isolated from an oil reservoir in Brazil.
Aims: To identify Bacillus spp. responsible of the fermentation of Hibiscus sabdariffa for produ... more Aims: To identify Bacillus spp. responsible of the fermentation of Hibiscus sabdariffa for production of Bikalga, an alkaline fermented food used as a condiment in Burkina Faso.Methods and Results: Seventy bacteria were isolated from Bikalga produced in different regions of Burkina Faso and identified by phenotyping and genotyping using PCR amplification of the 16S-23S rDNA intergenic transcribed spacer (ITS-PCR), repetitive sequence-based PCR (rep-PCR) and DNA sequencing. The isolates were characterized as motile, rod-shaped, endospore forming, catalase positive, Gram-positive bacteria. ITS-PCR allowed typing mainly at species level. Rep-PCR was more discriminative and allowed a typing at ssp. level. The DNA sequencing combined with the Blast search program and fermentation profiles using API 50CHB system allowed an identification of the bacteria as Bacillus subtilis, B. licheniformis, B. cereus, B. pumilus, B. badius, Brevibacillus bortelensis, B. sphaericus and B. fusiformis. B. subtilis were the predominant bacterium (42) followed by B. licheniformis (16).Conclusions: Various species and ssp. of Bacillus are involved in fermentation of H. sabdariffa for production of Bikalga.Significance and Impact of the study: Selection of starter cultures of Bacillus for controlled production of Bikalga, selection of probiotic bacteria.
Bacillus spp. are the predominant microorganisms in fermented African locust bean called Soumbala... more Bacillus spp. are the predominant microorganisms in fermented African locust bean called Soumbala in Burkina Faso. Ten strains selected as potential starter cultures were characterised by PCR amplification of the16S-23S rDNA intergenic transcribed spacer (ITS-PCR), restriction fragment length polymorphism of the ITS-PCR (ITS-PCR RFLP), pulsed field gel electrophoresis (PFGE) and sequencing of the 968-1401 region of the 16S rDNA. In previous studies, the isolates were identified by phenotyping as Bacillus subtilis and Bacillus pumilus. The phenotyping was repeated as a reference in the present study. The ITS-PCR and ITS-PCR RLFP allowed a typing at species level. The PFGE was more discriminative and allowed a typing at strain level. Full agreement with the phenotyping was observed in all cases. The sequencing of the 16S rDNA allowed the identification at species level with an identity from 97% to 100% comparing the sequences to those from the GenBank databases. The desired cultures of B. subtilis and B. pumilus from African locust bean fermentation were distinguished by ITS-PCR and ITS-PCR RLFP from Bacillus cereus and Bacillus sphaericus which sometimes occur in the beginning of the fermentation.
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