Aims: To determine antibacterial activity in lactic acid bacteria (LAB) silage inoculants and in wheat and corn silages which were treated with these inoculants. Methods and Results: Wheat and two corn silages were prepared in 0AE25 l sealed glass jars. Inoculant treatments were prepared for each type of silage with each of 10 LAB silage inoculants at inoculation rate of 10 6 CFU g )1 . Untreated silages served as controls. Antibacterial activity was determined in the inoculants and in their respective silages with Micrococcus luteus and Pseudomonas aeruginosa. Antibacterial activity was detected in nine of the 10 inoculants whereas such activity in the silages varied. Control silages did not have antibacterial activity. Conclusions: Many LAB silage inoculants have antibacterial activity and in some cases this activity is imparted on inoculated silages. Significance and Impact of the Study: This study was conducted as part of a broader research objective, which is to find out how LAB silage inoculants enhance ruminant performance. The results of this study indicate that LAB silage inoculants produce antibacterial activity, and therefore, have a potential to inhibit detrimental microorganisms in the silage or in the rumen.

The effect of hydroxylamine (NH2OH), p‐aminobenzoic acid (PABA) and p‐aminosalicylic acid (PASA) on the spectrum of the final product (s) formed when o‐dihydroxy‐ and trihydroxyphenols were oxidized by tyrosinase was examined. New pigmented product(s), probably oximes, were formed by the interaction of NH2OH with the o‐quinones of 4‐methyl catechol, 3,4‐dihydroxyphenylacetic acid (DOPAC) and 3,4‐dihydroxyphenylpropionic acid (3,4‐DPPA) but not with the o‐quinones of catechol or protocatechuic acid. Interaction of PABA or PASA with the o‐quinones of catechol, 4‐methyl catechol, protocatechuic acid, DOPAC and 3,4‐DPPA also yielded pigmented oximes. The interaction of the o‐quinones of trihydroxyphenols with NH2OH, PABA or PASA had little effect on the spectrum of the final product (s), suggesting that oximes are not formed in these reactions.

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This study aimed to assess the occurrence of toxigenic fungi and mycotoxin contamination in stored wheat grains by using advanced molecular and analytical techniques. A multiplex polymerase chain reaction (PCR) strategy was established for rapid identification of mycotoxigenic fungi, and an improved analytical method was developed for simultaneous multi-mycotoxin determination in wheat grains by liquid chromatography-tandem mass spectrometry (LC/MS/MS) without the need for any clean-up. The optimized multiplex PCR method was highly specific in detecting fungal species containing species-specific and mycotoxin metabolic pathway genes. The method was applied for evaluation of 34 wheat grain samples collected from storage warehouses for the presence of mycotoxin-producing fungi, and a few samples were found positive for Fusarium and Aspergillus species. Further chemical analysis revealed that 17 samples contained mycotoxins above the level of detection, but only six samples were found to be contaminated over the EU regulatory limits with at least one mycotoxin. Aflatoxin B1, fumonisins, and deoxynivalenol were the most common toxins found in these samples. The results showed a strong correlation between the presence of mycotoxin biosynthesis genes as analyzed by multiplex PCR and mycotoxin detection by LC/MS/MS. The present findings indicate that a combined approach might provide rapid, accurate, and sensitive detection of mycotoxigenic species and mycotoxins in wheat grains.

Our bioinspired, superhydrophobic surfaces show exceptional ability to passively inhibit the biofilm formation of Gram-positive and Gram-negative bacteria over a 7 day period.

Pathogenic fungi must respond effectively to changes in environmental pH for successful host colonization, virulence and toxin production. Aspergillus carbonarius is a mycotoxigenic pathogen with the ability to colonize many plant hosts and secrete ochratoxin A (OTA). In this study, we characterized the functions and addressed the role of PacC-mediated pH signaling in A. carbonarius pathogenicity using designed pacC gene knockout mutant. AcpacC mutant displayed an acidity-mimicking phenotype, which resulted in impaired fungal growth at neutral/alkaline pH, accompanied by reduced sporulation and conidial germination compared to the wild type (WT) strain. The AcpacC mutant was unable to efficiently acidify the growth media as a direct result of diminished gluconic and citric acid production. Furthermore, loss of AcpacC resulted in a complete inhibition of OTA production at pH 7.0. Additionally, AcpacC mutant exhibited attenuated virulence compared to the WT toward grapes and nectarine fruits. Reintroduction of pacC gene into AcpacC mutant restored the WT phenotype. Our results demonstrate important roles of PacC of A. carbonarius in OTA biosynthesis and in pathogenicity by controlling transcription of genes important for fungal secondary metabolism and infection.

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