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Shiladitya Dassarma - One of the best experts on this subject based on the ideXlab platform.
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Comparative Genomics of Halobacterium Strains From Diverse Locations
Microbial Diversity in the Genomic Era, 2018Co-Authors: Priya Dassarma, Melinda D Capes, Shiladitya DassarmaAbstract:Abstract Haloarchaea are salt-loving microorganisms that are members of the Third Domain of Life, the Archaea. They possess compact guanine and cytosine (GC)-rich genomes with large extrachromosomal replicons. Genome analysis of a common genus of Haloarchaea, Halobacterium, isolated from salts and salted foods from geographically diverse locations has shown that they contain stable and conserved 2-mega base pairs (Mbp) chromosomes and diverse megaplasmids containing many transposable insertion sequence (IS) elements. In this chapter, we provide an overview on Haloarchaea, followed by a case study on the comparative genomics of closely related Halobacterium species. We detail results on the 2 most highly studied, completely sequenced Halobacterium strains, NRC-1 and R-1, and genotypic analysis of 16 additional strains isolated from diverse locations. Our results illustrate the small number of differences in the main chromosome, and a large number of variations found in the plasmids, and suggest the existence of multiple clades (operational taxonomical units or OTUs) in the Halobacterium genus.
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Halobacterium expression system for production of full length plasmodium falciparum circumsporozoite protein
2016Co-Authors: Priya Dassarma, Shiladitya Dassarma, Wolf T Pecher, Ram Karan, Photini SinnisAbstract:We recently developed a novel expression system employing the halophilic Archaeon Halobacterium sp. NRC-1 for scaled-up production and nanoparticle-display of antigenic proteins. Here, we have targeted the major human parasite Plasmodium falciparum circumsporozoite protein (CSP), which is of interest for formulation of a protective malaria vaccine. A codon-optimized synthetic gene coding the full-length CSP was inserted downstream of the strong promoter for gvpA, the major gas vesicle nanoparticle protein gene, in the pDRK expression vector, and as a fusion to the gvpC protein in the pSD expression vector for display on the surface of gas vesicle nanoparticles. We found that the pDRK-CSP expression plasmid programmed high-level production of full-length CSP and the pSD-CSP expression plasmid programmed production of a GvpC-CSP fusion protein, for display on gas vesicle nanoparticles. The Halobacterium sp. expression system provides a novel approach and a potentially valuable technical advancement for the production of P. falciparum CSP for malaria vaccine development.
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Transcriptional profiling of the model Archaeon Halobacteriumsp. NRC-1: responses to changes in salinity and temperature
Saline Systems, 2007Co-Authors: James A Coker, Priya Dassarma, Jeffrey Kumar, Jochen A Müller, Shiladitya DassarmaAbstract:Background The model halophile Halobacterium sp. NRC-1 was among the first Archaea to be completely sequenced and many post-genomic tools, including whole genome DNA microarrays are now being applied to its analysis. This extremophile displays tolerance to multiple stresses, including high salinity, extreme (non-mesophilic) temperatures, lack of oxygen, and ultraviolet and ionizing radiation. Results In order to study the response of Halobacterium sp. NRC-1 to two common stressors, salinity and temperature, we used whole genome DNA microarrays to assay for changes in gene expression under differential growth conditions. Cultures grown aerobically in rich medium at 42°C were compared to cultures grown at elevated or reduced temperature and high or low salinity. The results obtained were analyzed using a custom database and microarray analysis tools. Growth under salt stress conditions resulted in the modulation of genes coding for many ion transporters, including potassium, phosphate, and iron transporters, as well as some peptide transporters and stress proteins. Growth at cold temperature altered the expression of genes involved in lipid metabolism, buoyant gas vesicles, and cold shock proteins. Heat shock showed induction of several known chaperone genes. The results showed that Halobacterium sp. NRC-1 cells are highly responsive to environmental changes at the level of gene expression. Conclusion Transcriptional profiling showed that Halobacterium sp. NRC-1 is highly responsive to its environment and provided insights into some of the specific responses at the level of gene expression. Responses to changes in salt conditions appear to be designed to minimize the loss of essential ionic species and abate possible toxic effects of others, while exposure to temperature extremes elicit responses to promote protein folding and limit factors responsible for growth inhibition. This work lays the foundation for further bioinformatic and genetic studies which will lead to a more comprehensive understanding of the biology of a model halophilic Archaeon.
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The uvrA, uvrB and uvrC genes are required for repair of ultraviolet light induced DNA photoproducts in Halobacterium sp. NRC-1
Saline Systems, 2006Co-Authors: David J Crowley, Shiladitya Dassarma, Brian R Berquist, Ivan Boubriak, Monika Clark, Emily Richard, Lynn Sullivan, Shirley MccreadyAbstract:Background Sequenced archaeal genomes contain a variety of bacterial and eukaryotic DNA repair gene homologs, but relatively little is known about how these microorganisms actually perform DNA repair. At least some archaea, including the extreme halophile Halobacterium sp . NRC-1, are able to repair ultraviolet light (UV) induced DNA damage in the absence of light-dependent photoreactivation but this 'dark' repair capacity remains largely uncharacterized. Halobacterium sp. NRC-1 possesses homologs of the bacterial uvrA , uvrB , and uvrC nucleotide excision repair genes as well as several eukaryotic repair genes and it has been thought that multiple DNA repair pathways may account for the high UV resistance and dark repair capacity of this model halophilic archaeon. We have carried out a functional analysis, measuring repair capability in uvrA , uvrB and uvrC deletion mutants. Results Deletion mutants lacking functional uvrA , uvrB or uvrC genes, including a uvrA uvrC double mutant, are hypersensitive to UV and are unable to remove cyclobutane pyrimidine dimers or 6–4 photoproducts from their DNA after irradiation with 150 J/m^2 of 254 nm UV-C. The UV sensitivity of the uvr mutants is greatly attenuated following incubation under visible light, emphasizing that photoreactivation is highly efficient in this organism. Phylogenetic analysis of the Halobacterium uvr genes indicates a complex ancestry. Conclusion Our results demonstrate that homologs of the bacterial nucleotide excision repair genes uvrA , uvrB , and uvrC are required for the removal of UV damage in the absence of photoreactivating light in Halobacterium sp. NRC-1. Deletion of these genes renders cells hypersensitive to UV and abolishes their ability to remove cyclobutane pyrimidine dimers and 6–4 photoproducts in the absence of photoreactivating light. In spite of this inability to repair UV damaged DNA, uvrA , uvrB and uvrC deletion mutants are substantially less UV sensitive than excision repair mutants of E. coli or yeast. This may be due to efficient damage tolerance mechanisms such as recombinational lesion bypass, bypass DNA polymerase(s) and the existence of multiple genomes in Halobacterium . Phylogenetic analysis provides no clear evidence for lateral transfer of these genes from bacteria to archaea.
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the uvra uvrb and uvrc genes are required for repair of ultraviolet light induced dna photoproducts in Halobacterium sp nrc 1
Saline Systems, 2006Co-Authors: David J Crowley, Shiladitya Dassarma, Brian R Berquist, Ivan Boubriak, Emily Richard, Lynn Sullivan, Monika L Clark, Shirley MccreadyAbstract:Background Sequenced archaeal genomes contain a variety of bacterial and eukaryotic DNA repair gene homologs, but relatively little is known about how these microorganisms actually perform DNA repair. At least some archaea, including the extreme halophile Halobacterium sp. NRC-1, are able to repair ultraviolet light (UV) induced DNA damage in the absence of light-dependent photoreactivation but this 'dark' repair capacity remains largely uncharacterized. Halobacterium sp. NRC-1 possesses homologs of the bacterial uvrA, uvrB, and uvrC nucleotide excision repair genes as well as several eukaryotic repair genes and it has been thought that multiple DNA repair pathways may account for the high UV resistance and dark repair capacity of this model halophilic archaeon. We have carried out a functional analysis, measuring repair capability in uvrA, uvrB and uvrC deletion mutants.
A J Desai - One of the best experts on this subject based on the ideXlab platform.
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Halobacterium sp. SP1(1) as a starter culture for accelerating fish sauce fermentation
Journal of Applied Microbiology, 2010Co-Authors: A. V. Akolkar, D. Durai, A J DesaiAbstract:Application of Halobacterium sp. SP1(1) for the acceleration of fish sauce fermentation.
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Halobacterium sp sp1 1 as a starter culture for accelerating fish sauce fermentation
Journal of Applied Microbiology, 2009Co-Authors: A. V. Akolkar, D. Durai, A J DesaiAbstract:Aims: Application of Halobacterium sp. SP1(1) for the acceleration of fish sauce fermentation. Methods and Results: Traditional fish sauce fermentation was mimicked using Halobacterium sp. SP1(1) as starter culture. Protease activity, peptide release and α-amino content (parameters used to monitor the progress of the fermentation) were high at day 10 in tests and day 20 in un-inoculated controls. The total protein and nitrogen contents were also high in tests compared with controls. The amino acid profile observed at the end of fermentation in experimental samples, when compared with the commercial sauce preparation, was found to be better with respect to flavour and aroma contributing amino acids as well as essential amino acid lysine. Microflora analysis of the final fish sauce revealed the absence of any nonhalophilic or halotolerant micro-organisms. The protease-producing halophilic isolates obtained from the fish sauce of eviscerated and uneviscerated controls were identified as Halobacterium sp. F1 and F2, respectively, by 16S rDNA sequence analysis. Conclusions: Exogenous augmentation of Halobacterium sp. SP1(1) accelerated the fish sauce fermentation process with an additive effect on the existing natural microflora present in the fish during fermentation. Halobacterium sp SP1(1), therefore, can be used as an important starter culture for accelerating the fish fermentation process, which is attributed to its extracellular protease. Significance and Impact of the Study: The present study is the first report on use of Halobacterium species as a starter culture for accelerating fish sauce fermentation. Use of halobacterial starter cultures may revolutionize the process in fish sauce industries by reducing the fermentation time and making the process more economical with improved nutritive value of product.
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organic solvent tolerance of Halobacterium sp sp1 1 and its extracellular protease
Journal of Basic Microbiology, 2008Co-Authors: A. V. Akolkar, D. Durai, Gauravi M Deshpande, Kandarp N Raval, Anuradha S Nerurkar, A J DesaiAbstract:Halophilic archaea belonging to three different genera- Halobacterium, Haloarcula and Haloferax, were isolated from Kandla salt pans. The isolates had an optimum requirement of 25% NaCl for growth. Increase in organic solvent tolerance of isolates was observed at higher NaCl concentrations. Among the three isolates Halobacterium sp. SP1(1) was found to be more tolerant than Haloarcula sp. SP2(2) and Haloferax sp. SP1(2a). The extracellular protease of Halobacterium sp. SP1(1) showed higher solvent tolerance compared to the organism itself. The enzyme was highly tolerant to toluene, xylene, n-decane, n-dodecane and n-undecane, majority of which are frequently used in paints. These findings may help in understanding the mechanism of organic solvent tolerance in halophilic archaea and their application in antifouling coatings. Also, best to our knowledge the present study is the first report on organic solvent tolerance of haloarchaeal extracellular protease. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Leroy Hood - One of the best experts on this subject based on the ideXlab platform.
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The Inferelator: an algorithm for learning parsimonious regulatory networks from systems-biology data sets de novo
Genome Biology, 2006Co-Authors: Richard Bonneau, Nitin S. Baliga, Leroy Hood, David J Reiss, Paul Shannon, Marc Facciotti, Vesteinn ThorssonAbstract:We present a method (the Inferelator) for deriving genome-wide transcriptional regulatory interactions, and apply the method to predict a large portion of the regulatory network of the archaeon Halobacterium NRC-1 . The Inferelator uses regression and variable selection to identify transcriptional influences on genes based on the integration of genome annotation and expression data. The learned network successfully predicted Halobacterium 's global expression under novel perturbations with predictive power similar to that seen over training data. Several specific regulatory predictions were experimentally tested and verified.
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proteomic analysis of an extreme halophilic archaeon Halobacterium sp nrc 1
Molecular & Cellular Proteomics, 2003Co-Authors: Eugene C Yi, Nitin S. Baliga, Leroy Hood, Ruedi Aebersold, David R Goodlett, Wailap Victor NgAbstract:Halobacterium sp. NRC-1 insoluble membrane and soluble cytoplasmic proteins were isolated by ultracentrifugation of whole cell lysate. Using an ion trap mass spectrometer equipped with a C18 trap electrospray ionization emitter/micro-liquid chromatography column, a number of trypsin-generated peptide tags from 426 unique proteins were identified. This represents approximately onefifth of the theoretical proteome of Halobacterium .O f these, 232 proteins were found only in the soluble fraction, 165 were only in the insoluble membrane fraction, and 29 were in both fractions. There were 72 and 61% previously annotated proteins identified in the soluble and membrane protein fractions, respectively. Interestingly, 57 of previously unannotated proteins found only in Halobacterium NRC-1 were identified. Such proteins could be interesting targets for understanding unique physiology of Halobacterium NRC-1. A group of proteins involved in various metabolic pathways were identified among the expressed proteins, suggesting these pathways were active at the time the cells were collected. This data containing a list of expressed proteins, their cellular locations, and biological functions could be used in future studies to investigate the interaction of the genes and proteins in relation to genetic or environmental perturbations. Molecular & Cellular Proteomics 2: 506 –524, 2003.
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coordinate regulation of energy transduction modules in Halobacterium sp analyzed by a global systems approach
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Nitin S. Baliga, Eugene C Yi, Ruedi Aebersold, David R Goodlett, Wailap Victor Ng, Paul Shannon, Krassen Dimitrov, Leroy HoodAbstract:The extremely halophilic archaeon Halobacterium NRC-1 can switch from aerobic energy production (energy from organic compounds) to anaerobic phototrophy (energy from light) by induction of purple membrane biogenesis. The purple membrane is made up of multiple copies of a 1:1 complex of bacterioopsin (Bop) and retinal called bacteriorhodopsin that functions as a light-driven proton pump. A light- and redox-sensing transcription regulator, Bat, regulates critical genes encoding the biogenesis of the purple membrane. To better understand the regulatory network underlying this physiological state, we report a systems approach using global mRNA and protein analyses of four strains of Halobacterium sp.: the wild-type, NRC-1; and three genetically perturbed strains: S9 (bat+), a purple membrane overproducer, and two purple membrane deficient strains, SD23 (a bop knockout) and SD20 (a bat knockout). The integrated DNA microarray and proteomic data reveal the coordinated coregulation of several interconnected biochemical pathways for phototrophy: isoprenoid synthesis, carotenoid synthesis, and bacteriorhodopsin assembly. In phototrophy, the second major biomodule for ATP production, arginine fermentation, is repressed. The primary systems level insight provided by this study is that two major energy production pathways in Halobacterium sp., phototrophy and arginine fermentation, are inversely regulated, presumably to achieve a balance in ATP production under anaerobic conditions.
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Genomic perspective on the photobiology of Halobacterium species NRC-1, a phototrophic, phototactic, and UV-tolerant haloarchaeon
Photosynthesis Research, 2001Co-Authors: Shiladitya Dassarma, Sean P. Kennedy, Brian Berquist, Wailap Victor Ng, Nitin S. Baliga, John L. Spudich, Mark P. Krebs, Jonathan A. Eisen, Carl H. Johnson, Leroy HoodAbstract:Halobacterium species display a variety of responses to light, including phototrophic growth, phototactic behavior, and photoprotective mechanisms. The complete genome sequence of Halobacterium species NRC-1 (Proc Natl Acad Sci USA 97: 12176–12181, 2000), coupled with the availability of a battery of methods for its analysis makes this an ideal model system for studying photobiology among the archaea. Here, we review: (1) the structure of the 2.57 Mbp Halobacterium NRC-1 genome, including a large chromosome, two minichromosomes, and 91 transposable IS elements; (2) the purple membrane regulon, which programs the accumulation of large quantities of the light-driven proton pump, bacteriorhodopsin, and allows for a period of phototrophic growth; (3) components of the sophisticated pathways for color-sensitive phototaxis; (4) the gas vesicle gene cluster, which codes for cell buoyancy organelles; (5) pathways for the production of carotenoid pigments and retinal, (6) processes for the repair of DNA damage; and (7) putative homologs of circadian rhythm regulators. We conclude with a discussion of the power of systems biology for comprehensive understanding of Halobacterium NRC-1 photobiology.
Nitin S. Baliga - One of the best experts on this subject based on the ideXlab platform.
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The Inferelator: an algorithm for learning parsimonious regulatory networks from systems-biology data sets de novo
Genome Biology, 2006Co-Authors: Richard Bonneau, Nitin S. Baliga, Leroy Hood, David J Reiss, Paul Shannon, Marc Facciotti, Vesteinn ThorssonAbstract:We present a method (the Inferelator) for deriving genome-wide transcriptional regulatory interactions, and apply the method to predict a large portion of the regulatory network of the archaeon Halobacterium NRC-1 . The Inferelator uses regression and variable selection to identify transcriptional influences on genes based on the integration of genome annotation and expression data. The learned network successfully predicted Halobacterium 's global expression under novel perturbations with predictive power similar to that seen over training data. Several specific regulatory predictions were experimentally tested and verified.
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proteomic analysis of an extreme halophilic archaeon Halobacterium sp nrc 1
Molecular & Cellular Proteomics, 2003Co-Authors: Eugene C Yi, Nitin S. Baliga, Leroy Hood, Ruedi Aebersold, David R Goodlett, Wailap Victor NgAbstract:Halobacterium sp. NRC-1 insoluble membrane and soluble cytoplasmic proteins were isolated by ultracentrifugation of whole cell lysate. Using an ion trap mass spectrometer equipped with a C18 trap electrospray ionization emitter/micro-liquid chromatography column, a number of trypsin-generated peptide tags from 426 unique proteins were identified. This represents approximately onefifth of the theoretical proteome of Halobacterium .O f these, 232 proteins were found only in the soluble fraction, 165 were only in the insoluble membrane fraction, and 29 were in both fractions. There were 72 and 61% previously annotated proteins identified in the soluble and membrane protein fractions, respectively. Interestingly, 57 of previously unannotated proteins found only in Halobacterium NRC-1 were identified. Such proteins could be interesting targets for understanding unique physiology of Halobacterium NRC-1. A group of proteins involved in various metabolic pathways were identified among the expressed proteins, suggesting these pathways were active at the time the cells were collected. This data containing a list of expressed proteins, their cellular locations, and biological functions could be used in future studies to investigate the interaction of the genes and proteins in relation to genetic or environmental perturbations. Molecular & Cellular Proteomics 2: 506 –524, 2003.
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coordinate regulation of energy transduction modules in Halobacterium sp analyzed by a global systems approach
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Nitin S. Baliga, Eugene C Yi, Ruedi Aebersold, David R Goodlett, Wailap Victor Ng, Paul Shannon, Krassen Dimitrov, Leroy HoodAbstract:The extremely halophilic archaeon Halobacterium NRC-1 can switch from aerobic energy production (energy from organic compounds) to anaerobic phototrophy (energy from light) by induction of purple membrane biogenesis. The purple membrane is made up of multiple copies of a 1:1 complex of bacterioopsin (Bop) and retinal called bacteriorhodopsin that functions as a light-driven proton pump. A light- and redox-sensing transcription regulator, Bat, regulates critical genes encoding the biogenesis of the purple membrane. To better understand the regulatory network underlying this physiological state, we report a systems approach using global mRNA and protein analyses of four strains of Halobacterium sp.: the wild-type, NRC-1; and three genetically perturbed strains: S9 (bat+), a purple membrane overproducer, and two purple membrane deficient strains, SD23 (a bop knockout) and SD20 (a bat knockout). The integrated DNA microarray and proteomic data reveal the coordinated coregulation of several interconnected biochemical pathways for phototrophy: isoprenoid synthesis, carotenoid synthesis, and bacteriorhodopsin assembly. In phototrophy, the second major biomodule for ATP production, arginine fermentation, is repressed. The primary systems level insight provided by this study is that two major energy production pathways in Halobacterium sp., phototrophy and arginine fermentation, are inversely regulated, presumably to achieve a balance in ATP production under anaerobic conditions.
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Genomic perspective on the photobiology of Halobacterium species NRC-1, a phototrophic, phototactic, and UV-tolerant haloarchaeon
Photosynthesis Research, 2001Co-Authors: Shiladitya Dassarma, Sean P. Kennedy, Brian Berquist, Wailap Victor Ng, Nitin S. Baliga, John L. Spudich, Mark P. Krebs, Jonathan A. Eisen, Carl H. Johnson, Leroy HoodAbstract:Halobacterium species display a variety of responses to light, including phototrophic growth, phototactic behavior, and photoprotective mechanisms. The complete genome sequence of Halobacterium species NRC-1 (Proc Natl Acad Sci USA 97: 12176–12181, 2000), coupled with the availability of a battery of methods for its analysis makes this an ideal model system for studying photobiology among the archaea. Here, we review: (1) the structure of the 2.57 Mbp Halobacterium NRC-1 genome, including a large chromosome, two minichromosomes, and 91 transposable IS elements; (2) the purple membrane regulon, which programs the accumulation of large quantities of the light-driven proton pump, bacteriorhodopsin, and allows for a period of phototrophic growth; (3) components of the sophisticated pathways for color-sensitive phototaxis; (4) the gas vesicle gene cluster, which codes for cell buoyancy organelles; (5) pathways for the production of carotenoid pigments and retinal, (6) processes for the repair of DNA damage; and (7) putative homologs of circadian rhythm regulators. We conclude with a discussion of the power of systems biology for comprehensive understanding of Halobacterium NRC-1 photobiology.
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genome sequence of Halobacterium species nrc 1
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Wailap Victor Ng, Nitin S. Baliga, Sean Kennedy, Gregory G Mahairas, Brian R Berquist, Hem Dutt Shukla, Stephen R Lasky, Vesteinn Thorsson, Jennifer L Sbrogna, Steven SwartzellAbstract:Abstract We report the complete sequence of an extreme halophile, Halobacterium sp. NRC-1, harboring a dynamic 2,571,010-bp genome containing 91 insertion sequences representing 12 families and organized into a large chromosome and 2 related minichromosomes. The Halobacterium NRC-1 genome codes for 2,630 predicted proteins, 36% of which are unrelated to any previously reported. Analysis of the genome sequence shows the presence of pathways for uptake and utilization of amino acids, active sodium-proton antiporter and potassium uptake systems, sophisticated photosensory and signal transduction pathways, and DNA replication, transcription, and translation systems resembling more complex eukaryotic organisms. Whole proteome comparisons show the definite archaeal nature of this halophile with additional similarities to the Gram-positive Bacillus subtilis and other bacteria. The ease of culturing Halobacterium and the availability of methods for its genetic manipulation in the laboratory, including construction of gene knockouts and replacements, indicate this halophile can serve as an excellent model system among the archaea.
A. V. Akolkar - One of the best experts on this subject based on the ideXlab platform.
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Halobacterium sp. SP1(1) as a starter culture for accelerating fish sauce fermentation
Journal of Applied Microbiology, 2010Co-Authors: A. V. Akolkar, D. Durai, A J DesaiAbstract:Application of Halobacterium sp. SP1(1) for the acceleration of fish sauce fermentation.
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Halobacterium sp sp1 1 as a starter culture for accelerating fish sauce fermentation
Journal of Applied Microbiology, 2009Co-Authors: A. V. Akolkar, D. Durai, A J DesaiAbstract:Aims: Application of Halobacterium sp. SP1(1) for the acceleration of fish sauce fermentation. Methods and Results: Traditional fish sauce fermentation was mimicked using Halobacterium sp. SP1(1) as starter culture. Protease activity, peptide release and α-amino content (parameters used to monitor the progress of the fermentation) were high at day 10 in tests and day 20 in un-inoculated controls. The total protein and nitrogen contents were also high in tests compared with controls. The amino acid profile observed at the end of fermentation in experimental samples, when compared with the commercial sauce preparation, was found to be better with respect to flavour and aroma contributing amino acids as well as essential amino acid lysine. Microflora analysis of the final fish sauce revealed the absence of any nonhalophilic or halotolerant micro-organisms. The protease-producing halophilic isolates obtained from the fish sauce of eviscerated and uneviscerated controls were identified as Halobacterium sp. F1 and F2, respectively, by 16S rDNA sequence analysis. Conclusions: Exogenous augmentation of Halobacterium sp. SP1(1) accelerated the fish sauce fermentation process with an additive effect on the existing natural microflora present in the fish during fermentation. Halobacterium sp SP1(1), therefore, can be used as an important starter culture for accelerating the fish fermentation process, which is attributed to its extracellular protease. Significance and Impact of the Study: The present study is the first report on use of Halobacterium species as a starter culture for accelerating fish sauce fermentation. Use of halobacterial starter cultures may revolutionize the process in fish sauce industries by reducing the fermentation time and making the process more economical with improved nutritive value of product.
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organic solvent tolerance of Halobacterium sp sp1 1 and its extracellular protease
Journal of Basic Microbiology, 2008Co-Authors: A. V. Akolkar, D. Durai, Gauravi M Deshpande, Kandarp N Raval, Anuradha S Nerurkar, A J DesaiAbstract:Halophilic archaea belonging to three different genera- Halobacterium, Haloarcula and Haloferax, were isolated from Kandla salt pans. The isolates had an optimum requirement of 25% NaCl for growth. Increase in organic solvent tolerance of isolates was observed at higher NaCl concentrations. Among the three isolates Halobacterium sp. SP1(1) was found to be more tolerant than Haloarcula sp. SP2(2) and Haloferax sp. SP1(2a). The extracellular protease of Halobacterium sp. SP1(1) showed higher solvent tolerance compared to the organism itself. The enzyme was highly tolerant to toluene, xylene, n-decane, n-dodecane and n-undecane, majority of which are frequently used in paints. These findings may help in understanding the mechanism of organic solvent tolerance in halophilic archaea and their application in antifouling coatings. Also, best to our knowledge the present study is the first report on organic solvent tolerance of haloarchaeal extracellular protease. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
