ABSTRACT
Chicken intestine harbors a vast number of bacterial strains. In the present study, antimicrobial substance produced by lactic acid bacteria (LAB) isolated from the gastrointestinal tract of healthy chicken was detected, characterized, and purified. Based on 16S rRNA sequencing, the bacteria were identified as Lactobacillus plantarum vN. The antimicrobial substance produced by this bacterium was designated vN-1 and exhibited a broad-spectrum of activity against many important pathogenic and spoilage microorganisms, including Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus luteus, Salmonella Typhimurium, and Erwinia amylovova. vN-1 was determined to be thermostable, insensitive to pH values ranging from 2.0 to 8.0, resistant to various organic solvents and to enzymatic inactivation. The inhibition kinetics displayed a bactericidal mode of action. This study revealed an antimicrobial substance with low molecular mass of less than 1 kDa as determined by ultrafiltration and having features not previously reported for LAB isolated from chicken intestines. The detection of this antimicrobial substance addresses an important aspect of biotechnological control agents of spoilage caused by Pseudomonas spp. and promises the possibility for preservation of refrigerated poultry meat. Practical Application: The newly characterized antimicrobial substance and designated as vN-1 may have the potential to be used in food preservation.
Subject(s)
Anti-Bacterial Agents/biosynthesis , Bacteriocins/biosynthesis , Intestines/microbiology , Lactobacillus plantarum/metabolism , Pseudomonas/drug effects , Animals , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Bacteriocins/isolation & purification , Bacteriocins/pharmacology , Chickens/microbiology , Food Microbiology/methods , Food Preservation/methods , Lactobacillus plantarum/isolation & purification , Meat/microbiology , Microbial Sensitivity Tests , Pseudomonas/isolation & purification , Staphylococcus aureus/drug effects , Staphylococcus aureus/isolation & purificationABSTRACT
Sex-pheromone production in the night flying female moth, Helicoverpa armigera is under neuroendocrine control due to the timely release of Pheromone Biosynthesis-Activating Neuropeptide (PBAN). Males orient to the females by upwind anemotaxis which usually leads to a successful mating. During copulation insect males transfer seminal peptides, produced in Male Accessory Glands (MAGs) which are implicated in post-mating behavioral changes of the females. These changes include the termination of pheromone biosynthesis and thus females do not re-mate. In previous studies we showed that synthetic Drosophila melanogaster Sex-Peptide (DrmSP), which is responsible for terminating receptivity in female flies, can terminate PBAN-stimulated pheromone production by pheromone glands of the female moth, H. armigera. In addition, we demonstrated that at least one fraction of the H. armigera MAG extract is both immunoreactive to DrmSP antibody and is pheromonostatic, we also showed that different sets of DrmSP-like immunoreactive peptides are up-regulated in the central nervous system of mated females. In the present study, we identify a putative receptor for sex-peptide (SP-R) in H. armigera on the basis of sequence homologies deposited in the GenBank. In addition, in an attempt to draw some light on the physiological significance of SP-like peptides in this moth, we conducted a differential expression study of this receptor comparing gene expression levels in relation to different photoperiods, sex and mating status of the moth. Photoperiod and mating influence SP-R gene expression levels and sexual dimorphic changes were observed in neural tissues due to the different physiological states. After mating SP-R transcript levels in female neural tissues and pheromone glands are up-regulated. Physiological studies in vivo confirm the up-regulation of gene expression levels in pheromone glands isolated from mated females.
Subject(s)
Insect Proteins , Moths , Neuropeptides/pharmacology , Receptors, Peptide , Reproduction/physiology , Sex Attractants/biosynthesis , Amino Acid Sequence , Animals , Base Sequence , Copulation , Drosophila melanogaster , Female , Gene Expression Regulation/drug effects , Insect Proteins/genetics , Insect Proteins/metabolism , Larva/physiology , Male , Molecular Sequence Data , Moths/genetics , Moths/metabolism , Neuropeptides/genetics , Neuropeptides/metabolism , Phylogeny , Receptors, Peptide/genetics , Receptors, Peptide/metabolism , Sequence Alignment , Sex Attractants/genetics , Sex Factors , Up-RegulationABSTRACT
Propionibacterium thoenii P-127 produces and releases to the growth medium antibacterial agents that can be used as natural preservatives. The concentrations of these antibacterial agents in the growth medium are very low, and their activity can be detected only in concentrated medium, even in a bioreactor. A simple and efficient system to produce propionicin PLG-1 without the use of a bioreactor was investigated. Fermentation in screw-cap bottles without shaking produced antibacterial activity similar to that of fermentation in plates, but in a shorter time. Sodium lactate medium (NaLa) was found to be the most supportive for PLG-1 production compared to lactic acid bacteria media such as M-17 or beet molasses/corn. The initial concentration of the carbon source, sodium lactate, agar concentration, and the initial pH of the medium affected the synthesis of PLG-1. Additions of NaCl up to 1% showed no effect on the antibacterial agent production. The optimal conditions for production of the antibacterial agent were fermentation for 9 days in screw-cap bottles in modified NaLa medium (M-NaLa) containing 1% yeast extract, 1% tryptic soy broth, 0.9% lactic acid, and 0.6% agar, adjusted to pH of 9.
