With the advent of antimicrobial resistance in animal pathogens, novel methods to combat infectious diseases are being sought. Among these, probiotics have been proposed as a means of promoting ...animal health but problems with their use has been reported. Research has demonstrated that bioactive molecules produced during the growth of certain probiotics interfere with bacterial cell-to-cell communication, which consequently results in an attenuation of virulence in a number of pathogens, including E. coli. The objective of this study was to determine the efficacy of the bioactive molecules, termed proteobiotics, produced by Lactobacillus acidophilus in preventing enterotoxigenic E, coli (ETEC) infection in pigs, which is the etiological agent for enteric colibacillosis, a common disease of nursing and young pigs.
To achieve this, piglets were fed a preparation of the bioactive at four levels: 0, 0.5×, 1.0× and 2.0× for 7 days prior to challenge with E. coli K88. There were 36 pigs (18 gilts and 18 barrows) per treatment, resulting in 144 piglets in total for the study. Each pen had 6 piglets (3 gilts and 3 barrows). Only piglets with no physical abnormality or conditions were used in the trial and intact male piglets and ridglings were excluded. The bioactive continued to be fed to the pigs post-challenge. Based of fecal and demeanour scores, pigs fed the low and high dose of the proteobiotic were significanlty less likely to show symptoms of illness than pigs fed no bioactive. While not being significant, the weight gain of pigs given the proteobiotics was improved. At day 4 following challenge, almost 50% of piglets that did not receive the proteobiotic were shedding ETEC in their feces, compared with about 15% of animals receiving the supplement. There was also an indication that the proteobiotics reduced colonization of the ileum by E. coli K88 and improved gut health.
This study indicates that the bioactive molecules produced by L. acidophilus reduces incidence of enteric colibacillosis in pigs and their use on farms would help to reduce antibiotic use.
A variety of plant products have been recognized for their antifungal activity and recently have attracted food industry attention for their efficacy in controlling postharvest fungal decay of ...fruits. The antifungal activity of perillaldehyde (PAE) was evaluated against Aspergillus niger, a known cause of grape spoilage, and possible mechanisms were explored. PAE showed notable antifungal activity against A. niger, with a minimum inhibitory concentration (MIC) and a minimum fungicidal concentration (MFC) of 0.25 and 1μl/ml, respectively. The accumulation of mycelial biomass was also inhibited by PAE in a dose-dependent manner, completely inhibiting mycelial growth at 1μl/ml. In vivo data confirmed that the vapour treatment of grapes with various concentrations of PAE markedly improved control of A. niger and suppressed natural decay. Concentrations of PAE of 0.075μl/ml air showed the greatest inhibition of fungal growth compared to the controls. Further experiments indicated that PAE activated a membrane-active mechanism that inhibits ergosterol synthesis, increases membrane permeability (as evidenced by extracellular pH and conductivity measurements), and disrupts membrane integrity, leading to cell death. Our findings suggest that this membrane-active mechanism makes PAE a promising potential antifungal agent for postharvest control of grape spoilage.
•Perillaldehyde displayed notable in vitro antifungal activity against A. niger.•Practical efficacy of perillaldehyde was established as fumigant in grapes.•The membrane permeability of A. niger are changed by perillaldehyde.•The ergosterol synthesis and membrane integrity were affected by perillaldehyde.•Perillaldehyde could be used as a potential source of eco-friendly preservative.
The antifungal activity of Nerol (NEL) was evaluated against Aspergillus niger, a known cause of grape spoilage, and possible modes of action were explored. The antifungal efficacy of NEL against ...A. niger has been proven in a dose-dependent manner through in vitro (mycelial growth and spore germination) and in vivo (grapes) tests. An obvious increase in the membrane permeability was detected through the determination of extracellular pH and conductivity. The damage in the cell membrane was measured by monitoring the influx of Propidium iodide (PI) using flow cytometry and was further verified through the inhibition of ergosterol synthesis in the cell membrane. NEL induced morphological changes, and the integrity of the A. niger fungal cells decreased with increasing NEL concentrations. A dose-dependent decrease in ergosterol production was also seen in A. niger cell membranes upon exposure to NEL. The mechanism-of-action study revealed that NEL activated a membrane-active mechanism that inhibits ergosterol synthesis and consequently compromised the membrane integrity of A. niger. As a result, the membrane permeability changes and causes cell death. The membrane lesion mechanism makes NEL a natural alternative to commercial fungicide for control of stored grape spoilage.
•Nerol displayed notable in vitro antifungal activity against A. niger.•Practical efficacy of nerol was established as fumigant in grapes.•The membrane permeability of A. niger are changed by nerol.•The ergosterol synthesis and membrane integrity were affected by nerol.•Nerol could be used as a potential source of eco-friendly preservative.
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