Project description:l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA) as a bioactive compound.
Project description:This data displays both known and unknown extra-cellular proteins from 13 species of Lactic Acid bacteria found in the honey-crop of the honeybee Apis. mellifera mellifera. The tryptic peptides from the secreted proteins were run on an Agilent HPLC on a C18 reverse phase column (75 µm x 150 mm, particle size 3 µm). Total run time was 90 min and flow rate 300 nl/min. Buffers used for gradient was 0.1% formic acid in water (buffer A) and 0.1% formic acid in acetonitrile (buffer B). The buffer mixing was 5 min 5% buffer B, followed by 5%-45% buffer B in a linear gradient for 50 min, followed by 45%-80% buffer B in a linear gradient for 5 min. The 80% of buffer B was then kept for 15 min and then rapidly back to 5% buffer B for the final 15 min. The fractions from HPLC were loaded on an LCQ Deca XP Plus Ion trap mass spectrometer (ThermoScientific). Genomic DNA were prepared from all 13 LAB strains depicted earlier and sequenced at MWG Eurofins Operon (Ebensburg, Germany) using Roche GS FLX Titanium technology from Roche (Basel, Switzerland). For each genome a shotgun library was constructed with up to 700,000 reads per segment and was generated by sequencing in 2x half segment of a full FLX+ run. Each genome had an 8 kpb long-paired end library constructed. Approximately 300,000 true paired end reads, sequence tags, and scaffolds with GS FLX+ chemistry using 2x half segment of a full run were generated. Clonal amplification was performed by emPCR in both library types. The sequencing was continued until 15-20 fold coverage was reached. The obtained reads were assembled by the software Newbler 2.6 from Roche (Basel, Switzerland). ORF prediction and automated annotation was performed at Integrated Genomics Assets Inc. (Mount Prospect, Illinois, USA). In ORF prediction three different software were used, GLIMMER, Critica, and Prokpeg. Automated annotation was performed with the ERGOTM algorithms (Integrated Genomics Assets Inc. Mount Prospect, Illinois, USA). The resulting mass spectra-files obtained from the mass spectrometry analysis were searched using MASCOT against a local database containing the predicted proteome of the 13 LAB. We used a cut off Ions score of 38 as a value for determining that the protein was identified. Individual ion scores that were greater than 38 indicated identity or extensive homology (p<0.05) of the protein. Protein sequence similarity searches were performed with software BLASTP in the software package BLAST 2.27+ against a non-redundant protein database at NCBI. Pfam (default database), and InterProScan (default databases). Expressed proteins identified by peptide mass fingerprinting were manually re-annotated.
Project description:Thirty-one lactic acid bacterial strains from different species were evaluated for exopolysaccharide (EPS) production in milk. Thermophilic strains produced more EPS than mesophilic ones, but EPS yields were generally low. Ropiness or capsular polysaccharide formation was strain dependent. Six strains produced high-molecular-mass EPS. Polymers were classified into nine groups on the basis of their monomer composition. EPS from Enterococcus strains were isolated and characterized.
Project description:Lactic acid-producing bacteria are important in many fermentations, such as the production of biobased plastics. Insight in the competitive advantage of lactic acid bacteria over other fermentative bacteria in a mixed culture enables ecology-based process design and can aid the development of sustainable and energy-efficient bioprocesses. Here we demonstrate the enrichment of lactic acid bacteria in a controlled sequencing batch bioreactor environment using a glucose-based medium supplemented with peptides and B vitamins. A mineral medium enrichment operated in parallel was dominated by Ethanoligenens species and fermented glucose to acetate, butyrate and hydrogen. The complex medium enrichment was populated by Lactococcus, Lactobacillus and Megasphaera species and showed a product spectrum of acetate, ethanol, propionate, butyrate and valerate. An intermediate peak of lactate was observed, showing the simultaneous production and consumption of lactate, which is of concern for lactic acid production purposes. This study underlines that the competitive advantage for lactic acid-producing bacteria primarily lies in their ability to attain a high biomass specific uptake rate of glucose, which was two times higher for the complex medium enrichment when compared to the mineral medium enrichment. The competitive advantage of lactic acid production in rich media can be explained using a resource allocation theory for microbial growth processes.
Project description:The aim of the study was to characterize the probiotic qualities and siderophore production of Enterococcus and Bacillus isolates for possible application for iron nutrition in human and animals strains were selectively isolated from different dairy sources and infant faecal matter. Isolates SB10, JC13 and IFM22 were found to produce maximum siderophore ranging from 65-90% at an optimum pH 7, incubation period of 96 h, agitation speed of 150 rpm and inoculum volume of 15%. SB10 and JC13 were found to show high homology with Enterococcus spp. and IFM22 with Bacillus spp., using partial 16S rRNA sequencing and biochemical characterization. All the three isolates produced hydroxymate type of siderophores under iron stressed conditions and screened for probiotic characters as per WHO guidelines. Strains have shown excellent tolerance to acid, bile salt, sodium chloride and phenol. They were non-haemolytic in nature and exhibited high hydrophobicity and autoaggregation. Our isolates proved to be potent probiotic strains due to their survival under highly acidic conditions and higher tolerance to bile salt. In addition, its colonization efficiency was proved by exhibiting high autoaggregation and hydrophobicity.