Project description:The ability to produce diacetyl from pyruvate and l-serine was studied in various strains of Pediococcus pentosaceus and Pediococcus acidilactici isolated from cheese. After being incubated on both substrates, only P. pentosaceus produced significant amounts of diacetyl. This property correlated with measurable serine dehydratase activity in cell extracts. A gene encoding the serine dehydratase (dsdA) was identified in P. pentosaceus, and strains that showed no serine dehydratase activity carried mutations that rendered the gene product inactive. A functional dsdA was cloned from P. pentosaceus FAM19132 and expressed in Escherichia coli. The purified recombinant enzyme catalyzed the formation of pyruvate from L- and D-serine and was active at low pH and elevated NaCl concentrations, environmental conditions usually present in cheese. Analysis of the amino acid profiles of culture supernatants from dsdA wild-type and dsdA mutant strains of P. pentosaceus did not show differences in serine levels. In contrast, P. acidilactici degraded serine. Moreover, this species also catabolized threonine and produced alanine and α-aminobutyrate.
Project description:The presence of anti-microbial phenolic compounds, such as the model compound ferulic acid, in biomass hydrolysates poses significant challenges to the widespread use of biomass in conjunction with whole cell biocatalysis or fermentation. Currently, these inhibitory compounds must be removed through additional downstream processing to create feedstock suitable for most industrially important microbial strains. This study explores the high ferulic acid tolerance in Lactobacillus brevis (L. brevis), a lactic acid bacteria often found in fermentation processes, by global transcriptional response analysis. The transcriptional profile of L. brevis under ferulic acid stress reveals that the presence of ferulic acid primarily triggers the expression of membrane proteins to counteract ferulic acid induced changes in membrane fluidity and ion leakage, in the midst of a generalized stress response. Several promising routes for understanding phenolic acid tolerance have been identified based upon these findings. These insights may be used to guide further engineering of model industrial organisms to better tolerate phenolic compounds in processed biomass.
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:BackgroundPediococcus pentosaceus, a promising strain of lactic acid bacteria (LAB), is gradually attracting attention, leading to a rapid increase in experimental research. Due to increased demand for practical applications of microbes, the functional and harmless P. pentosaceus might be a worthwhile LAB strain for both the food industry and biological applications.ResultsAs an additive, P. pentosaceus improves the taste and nutrition of food, as well as the storage of animal products. Moreover, the antimicrobial abilities of Pediococcus strains are being highlighted. Evidence suggests that bacteriocins or bacteriocin-like substances (BLISs) produced by P. pentosaceus play effective antibacterial roles in the microbial ecosystem. In addition, various strains of P. pentosaceus have been highlighted for probiotic use due to their anti-inflammation, anticancer, antioxidant, detoxification, and lipid-lowering abilities.ConclusionsTherefore, it is necessary to continue studying P. pentosaceus for further use. Thorough study of several P. pentosaceus strains should clarify the benefits and drawbacks in the future.
Project description:We report the 1.8-Mb genome sequence of Pediococcus pentosaceus strain IE-3, isolated from a dairy effluent sample. The whole-genome sequence of this strain will aid in comparative genomics of Pediococcus pentosaceus strains of diverse ecological origins and their biotechnological applications.
Project description:We report here the draft genome sequence of Pediococcus pentosaceus strain IMI 507024, a lactic acid bacterium isolated from fermented sausage in Kentucky (Nicholasville, KY, USA). The strain is deposited in the Centre for Agriculture and Bioscience International (CABI) Culture Collection with the accession number IMI 507024.