Project description:Pastick2009 - Genome-scale metabolic network
of Streptococcus thermophilus (iMP429)
This model is described in the article:
Genome-scale model of
Streptococcus thermophilus LMG18311 for metabolic comparison of
lactic acid bacteria.
Pastink MI, Teusink B, Hols P,
Visser S, de Vos WM, Hugenholtz J.
Appl. Environ. Microbiol. 2009 Jun;
75(11): 3627-3633
Abstract:
In this report, we describe the amino acid metabolism and
amino acid dependency of the dairy bacterium Streptococcus
thermophilus LMG18311 and compare them with those of two other
characterized lactic acid bacteria, Lactococcus lactis and
Lactobacillus plantarum. Through the construction of a
genome-scale metabolic model of S. thermophilus, the metabolic
differences between the three bacteria were visualized by
direct projection on a metabolic map. The comparative analysis
revealed the minimal amino acid auxotrophy (only histidine and
methionine or cysteine) of S. thermophilus LMG18311 and the
broad variety of volatiles produced from amino acids compared
to the other two bacteria. It also revealed the limited number
of pyruvate branches, forcing this strain to use the
homofermentative metabolism for growth optimization. In
addition, some industrially relevant features could be
identified in S. thermophilus, such as the unique pathway for
acetaldehyde (yogurt flavor) production and the absence of a
complete pentose phosphate pathway.
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Project description:Lactobacillus helveticus is a rod-shaped lactic acid bacterium that is widely used in the manufacture of fermented dairy foods and for production of bioactive peptides from milk proteins. Although L. helveticus is commonly associated with milk environments, phylogenetic studies show it is closely related to an intestinal species, Lactobacillus acidophilus, which has been shown to impart probiotic health benefits to humans. This relationship has fueled a prevailing hypothesis that L. helveticus is a highly specialized derivative of L. acidophilus which has adapted to acidified whey. However, L. helveticus has also been sporadically recovered from non-dairy environments, which argues the species may not be as highly specialized as is widely believed. This study employed genome sequence analysis and comparative genome hybridizations to investigate genomic diversity among L. helveticus strains collected from cheese, whey, and whiskey malt, as well as commercial cultures used in manufacture of cheese or bioactive dairy foods. Results revealed considerable variability in gene content between some L. helveticus strains, and indicated the species should not be viewed as a strict dairy-niche specialist. In addition, comparative genomic analyses provided new insight on several industrially and ecologically important attributes of L. helveticus that may facilitate commercial strain selection. 42 samples were hybridized to the microarray chip, which contains probe sequences from L. helveticus CNRZ32. CNRZ32 was also hybridized and used as the reference sample. Data from the microarray was statistically analyzed using the R software. Samples were compared to the reference (CNRZ32) to investigate genome diversity amoung L. helveticus strains,
Project description:Lactobacillus helveticus is a rod-shaped lactic acid bacterium that is widely used in the manufacture of fermented dairy foods and for production of bioactive peptides from milk proteins. Although L. helveticus is commonly associated with milk environments, phylogenetic studies show it is closely related to an intestinal species, Lactobacillus acidophilus, which has been shown to impart probiotic health benefits to humans. This relationship has fueled a prevailing hypothesis that L. helveticus is a highly specialized derivative of L. acidophilus which has adapted to acidified whey. However, L. helveticus has also been sporadically recovered from non-dairy environments, which argues the species may not be as highly specialized as is widely believed. This study employed genome sequence analysis and comparative genome hybridizations to investigate genomic diversity among L. helveticus strains collected from cheese, whey, and whiskey malt, as well as commercial cultures used in manufacture of cheese or bioactive dairy foods. Results revealed considerable variability in gene content between some L. helveticus strains, and indicated the species should not be viewed as a strict dairy-niche specialist. In addition, comparative genomic analyses provided new insight on several industrially and ecologically important attributes of L. helveticus that may facilitate commercial strain selection.
2013-08-16 | GSE23660 | GEO
Project description:Lactic acid bacteria isolated from cheese
Project description:The detection of dairy processing is pivotal to our understanding of ancient subsistence strategies. This culinary process is linked to key arguments surrounding the evolution of lactase persistence in prehistory. Despite extensive evidence indicating the presence of dairy products in ceramics in the European Neolithic, questions remain about the nature and extent of milk (and lactose) processing and consumption. In order to investigate past patterns of dairy processing, here we analyse ancient proteins identified from Late Neolithic Funnel Beaker ceramics, scrutinising the principle that curd and whey proteins partition during the production of dairy foods from milk. Our results indicate the presence of casein-rich dairy products in these vessels suggesting the creation of curd-enriched products from raw milk. Moreover, this analysis reveals the use of multiple species for their dairy products in the Late Neolithic Funnel Beaker culture, adding to a growing body of evidence that multiple taxa were exploited for dairying in the Neolithic. Alongside palaeoproteomic analysis we also apply lipid residue analysis, with discrepancies in these two approaches suggesting that effects from isotope mixing may be underestimating the frequency of milk use in prehistoric pottery, highlighting the utility of a multi-stranded approach.
Project description:The detection of dairy processing is pivotal to our understanding of ancient subsistence strategies. This culinary process is linked to key arguments surrounding the evolution of lactase persistence in prehistory. Despite extensive evidence indicating the presence of dairy products in ceramics in the European Neolithic, questions remain about the nature and extent of milk (and lactose) processing and consumption. In order to investigate past patterns of dairy processing, here we analyse ancient proteins identified from Late Neolithic Funnel Beaker ceramics, scrutinising the principle that curd and whey proteins partition during the production of dairy foods from milk. Our results indicate the presence of casein-rich dairy products in these vessels suggesting the creation of curd-enriched products from raw milk. Moreover, this analysis reveals the use of multiple species for their dairy products in the Late Neolithic Funnel Beaker culture, adding to a growing body of evidence that multiple taxa were exploited for dairying in the Neolithic. Alongside palaeoproteomic analysis we also apply lipid residue analysis, with discrepancies in these two approaches suggesting that effects from isotope mixing may be underestimating the frequency of milk use in prehistoric pottery, highlighting the utility of a multi-stranded approach.
2023-05-10 | PXD037913 | Pride
Project description:Sequencing lactic acid bacteria isolated from cheese
Project description:Staphylococcus aureus is an important food poisoning bacterium. In food preservation, acidification is a well-known method. Permeant weak organic acids, like lactic and acetic acids, are known to be more effective against bacteria than inorganic strong acids (e.g., HCl). Growth experiments and metabolic and transcriptional analyses were used to determine the responses of a food pathogenic S. aureus strain exposed to lactic acid, acetic acid, and HCl at pH 4.5. Lactic and acetic acid stress induced a slower transcriptional response and large variations in growth patterns compared with the responses induced by HCl. In cultures acidified with lactic acid, the pH of the medium gradually increased to 7.5 during growth, while no such increase was observed for bacteria exposed to acetic acid or HCl. Staphylococcus aureus increased the pH in the medium mainly through accumulation of ammonium and the removal of acid groups, resulting in increased production of diacetyl (2,3-butanedione) and pyrazines. The results showed flexible and versatile responses of S. aureus to different types of acid stress. As measured by growth inhibition, permeant organic acid stress introduced severe stress compared with the stress caused by HCl. Cells exposed to lactic acid showed specific mechanisms of action in addition to sharing many of the mechanisms induced by HCl stress. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-87