Bioconversion of glycerol into polyhydroxyalkanoates through an atypical metabolism shift using Priestia megaterium during fermentation processes: A statistical analysis of carbon and nitrogen source concentrations.

Polyhydroxyalkanoates (PHA) are bioplastics which are well known as intracellular energy storage compounds and are produced in a large number of prokaryotic species. These bio-based inclusions are biodegradable, biocompatible and environmental friendly. Industrial production of, short chain and medium chain length PHA, involves the use of microorganisms and their enzymes.

New model development for qualitative and quantitative analysis of microbial polyhydroxyalkanoates: A comparison of Fourier Transform Infrared Spectroscopy with Gas Chromatography.

FT-IR spectroscopy is a non-destructive testing technique that requires minimal sample preparation time and allows the rapid characterization of structural features of complex, polymeric material. This technique has been frequently used in the past for the detection of PHA (Polyhydroxyalkanoates) but rarely for their quantification. In this work, by using cluster and discriminant statistical analysis of FT-IR data, different models are proposed for rapid identification of PHA monomers produced under different growth conditions by bacterial strains, and for their semi quantification.

Impact of biomass combustion on occurrence and distribution of aromatic hydrocarbons in apples.

Forest fires and biomass burning are known to generate aromatic hydrocarbons via incomplete combustions, due to high moisture, insufficient temperature, and oxygen content. These emission sources are particularly concerning because generated smokes cannot be treated and aromatic hydrocarbons can deposit on plant foods.The aim of this work was to study the potential deposition and absorption of monocyclic and polycyclic aromatic hydrocarbons in plant after exposure to smokes generated by burning wood.

Polycyclic aromatic hydrocarbons in fruits and vegetables: Origin, analysis, and occurrence.

Feed intake, for non-smokers, is the first route of contamination to polycyclic aromatic hydrocarbons (PAHs), which are potentially toxic compounds via ingestion. Investigations are focused on the presence of PAHs in fruits and vegetables. Transfer of PAHs can occur from air and soil during cultivation.

Impact of carbon source and variable nitrogen conditions on bacterial biosynthesis of polyhydroxyalkanoates: evidence of an atypical metabolism in Bacillus megaterium DSM 509.

Twenty bacterial strains were examined on their ability to produce polyhydroxyalkanoates (PHA) from different carbon sources under rich and depleted nitrogen conditions. Preliminary experiments with glucose as sole carbon source allowed to select PHA producing bacteria using FTIR spectroscopy. They were further tested with eight additional carbon substrates including organic, fatty acids or sugars.

Quantitative and qualitative variability of the caseinolytic potential of different strains of Pseudomonas fluorescens: implications for the stability of casein micelles of UHT milks during their storage.

Pseudomonas fluorescens grows at low temperature and produces thermo-resistant protease(s) that can destabilize UHT (Ultra High Temperature) milk during its storage. The consequences of contamination of microfiltered milk with 9 strains of P. fluorescens on the stability of the corresponding UHT milk during storage had been investigated in this study.

In vitro digestibility of α-casozepine, a benzodiazepine-like peptide from bovine casein, and biological activity of its main proteolytic fragment.

α-Casozepine is a peptide, corresponding to the sequence 91-100 of the bovine α(s1)-casein, displaying anxiolytic activity in the rat. The α(s1)-casein tryptic hydrolysate containing this peptide decreases stress effects after oral administration in various species including man. Therefore, the stability of this peptide toward gastric and pancreatic proteases has been assessed by using pepsin, chymotrypsin/trypsin, Corolase PP, pepsin followed by chymotrypsin/trypsin or pepsin followed by Corolase PP.

Identification of phosphorylation sites of equine beta-casein isoforms.

Equine beta-casein is phosphorylated at variable degrees and isoforms carrying 3 to 7 phosphate groups (3P-7P) have been found in milk, but the phosphorylated amino acid residues of each isoform are not yet identified. In the present work, the different phosphorylation variants were first isolated by ion-exchange chromatography and then hydrolysed by trypsin to generate caseinophosphopeptides (CPPs), each containing all the potential phosphorylation sites. The equine CPPs were prepared by metal oxide affinity chromatography, a method based on the affinity of phosphate groups towards titanium dioxide immobilized onto a micro-column.

Molecular typing of industrial strains of Pseudomonas spp. isolated from milk and genetical and biochemical characterization of an extracellular protease produced by one of them.

P. fluorescens is responsible for the highest depredation of milk because of its capacity to synthesize extracellular lipase and protease which hydrolyze milk fat and proteins. Several P.

The primary structure of a low-Mr multiphosphorylated variant of beta-casein in equine milk.

Highly phosphorylated casein with a low molecular mass was isolated from Haflinger mare's milk by RP-HPLC. It accounts for 4.0% of the casein content.

The Clarifying Reagent, or how to make the analysis of milk and dairy products easier.

Difficulties with the analysis of opaque milk and dairy products can be resolved by rendering the sample transparent. This allows direct photometric measurements of the reaction mixtures, and all sample pre-treatment steps become unnecessary. For this, several reagents have been reported in literature.

Determination of the phosphorylation level and deamidation susceptibility of equine beta-casein.

beta-Casein was isolated from Haflinger mare's milk by RP-HPLC, and displayed microheterogeneity by urea-electrophoresis and 2-DE probably due to a variable degree of phosphorylation. To investigate the degree of phosphorylation, the primary structure of equine beta-casein was determined by tryptic hydrolysis and MS of peptides released and by MS of the protein treated by alkaline phosphatase. The molecular mass found for the apo-form of Haflinger mare's beta-casein (25 514 +/- 3 Da) was close to the theoretical mass of the reported sequence (GenBank AAG43954) modified by insertion of a region (residues 27-34) encoded by an exon sometimes out-spliced (25 511.

Identification of an iron-binding protein of the Dps family expressed by Streptococcus thermophilus.

Streptococcus thermophilus PB18 can grow between 20 degrees and 52 degrees C and is resistant to various stresses such as heat, acidic or cold shock. During cold shock, a protein of 21.5 kDa was previously shown to be induced in S.

Angiotensin-I-converting enzyme inhibitory peptides from tryptic hydrolysate of bovine alphaS2-casein.

Angiotensin-I-converting enzyme (ACE) inhibitory activity of a tryptic digest of bovine alpha(S2)-casein (alpha(S2)-CN) was extensively investigated. Forty-three peptide peaks were isolated and tested. Seven casokinins (i.