-
Biochimica Et Biophysica Acta.... Aug 2023Antimicrobial peptides (AMPs) commonly target bacterial membranes and show broad-spectrum activity against microorganisms. In this research we used three AMPs (nisin,...
Antimicrobial peptides (AMPs) commonly target bacterial membranes and show broad-spectrum activity against microorganisms. In this research we used three AMPs (nisin, epilancin 15×, [R4L10]-teixobactin) and tested their membrane effects towards three strains (Staphylococcus simulans, Micrococcus flavus, Bacillus megaterium) in relation with their antibacterial activity. We describe fluorescence and luminescence-based assays to measure effects on membrane potential, intracellular pH, membrane permeabilization and intracellular ATP levels. The results show that our control peptide, nisin, performed mostly as expected in view of its targeted pore-forming activity, with fast killing kinetics that coincided with severe membrane permeabilization in all three strains. However, the mechanisms of action of both Epilancin 15× as well as [R4L10]-teixobactin appeared to depend strongly on the bacterium tested. In certain specific combinations of assay, peptide and bacterium, deviations from the general picture were observed. This was even the case for nisin, indicating the importance of using multiple assays and bacteria for mode of action studies to be able to draw proper conclusions on the mode of action of AMPs.
Topics: Nisin; Antimicrobial Peptides; Antimicrobial Cationic Peptides; Bacteria; Anti-Bacterial Agents
PubMed: 37100361
DOI: 10.1016/j.bbamem.2023.184160 -
Food Chemistry: X Mar 2024The aim of this study was to investigate and compare the effects of different mixed starter cultures ( and ) on the bacterial communities and flavor of fermented...
The aim of this study was to investigate and compare the effects of different mixed starter cultures ( and ) on the bacterial communities and flavor of fermented sausages. The results indicated that native starters grew well in fermented sausages and became dominant at the end of ripening. Among them, spp. had the highest relative abundance, followed by spp. In addition, the inoculation of the mixed starters promoted the formation of taste and aroma compounds that contribute to the overall flavor of the fermented sausages. Among them, the CQ01107 + CD207 (CCA) treatment was found to have the highest umami amino acid, nucleotide, lactic acid, fatty acid and ketone contents ( < 0.05), as well as excellent sensory properties. In conclusion, the CCA starter may be a desirable starter culture to enhance the flavor of fermented sausages.
PubMed: 38389578
DOI: 10.1016/j.fochx.2024.101225 -
Journal of Dairy Science May 2024There are limited data available regarding pathogens causing intramammary infections (IMI) in Jersey cows. The objectives of this study were to characterize the... (Observational Study)
Observational Study
There are limited data available regarding pathogens causing intramammary infections (IMI) in Jersey cows. The objectives of this study were to characterize the prevalence of IMI caused by different microorganisms in lactating Jersey cattle and evaluate the associations among microbes and somatic cell count (SCC) and persistence of IMI. This prospective, observational, longitudinal study included lactating Jersey cows (n = 753) from 4 farms within a 415 km radius of Columbia, Missouri. Quarter foremilk samples were aseptically collected monthly for 3 consecutive months. Microorganisms were identified using aerobic milk culture and MALDI-TOF mass spectrometry. A commercial laboratory measured SCC using flow cytometry. Milk culture results were used to classify single microorganism infections as persistent (same microorganism species identified at first sampling and one other sampling) or nonpersistent infection. Mixed models were built to evaluate the associations between IMI status and SCC natural logarithm (lnSCC), as well as persistence and lnSCC. Overall, staphylococci were the most commonly isolated microorganisms among the 7,370 quarter-level milk samples collected. Median prevalence (using all 3 samplings) of specific microbes varied among farms; however, Staphylococcus chromogenes was a common species found at all farms. The most common microbial species that persisted were Staph. chromogenes, Staphylococcus aureus, Staphylococcus simulans, and Streptococcus uberis. Streptococcus dysgalactiae and Staph. aureus were the IMI associated with the most inflammation based on lnSCC. The small number of herds included in this study with the large variation in herd type limits the generalizability of the data. However, results of this study seem to be similar to those of previous studies in other breeds, suggesting management factors are more important than breed-specific differences when evaluating causes of IMI and associated subclinical mastitis.
Topics: Cattle; Animals; Female; Milk; Lactation; Prevalence; Longitudinal Studies; Prospective Studies; Mastitis, Bovine; Staphylococcal Infections; Staphylococcus aureus; Cell Count; Cattle Diseases
PubMed: 37949401
DOI: 10.3168/jds.2023-23848