EndophyticBacillus subtilisStrain E1R-J Is a Promising Biocontrol Agent for Wheat Powdery Mildew

In this study, the biocontrol efficacies of 14 endophytic bacterial strains were tested againstBlumeria graminisf. sp.tritici(Bgt) in pot experiments under greenhouse conditions.Bacillus subtilisstrain E1R-j significantly reduced disease index and exhibited the best control (90.97%). When different formulations of E1R-j were sprayed 24 h beforeBgtinoculation, fermentation liquid without bacterial cell and crude protein suspension displayed the similar effects; and they reduced disease index more than bacterial cell suspension (109 cfu mL−1) and fermentation liquid without protein. The control effects were not significantly different between 1011and 109 cfu mL−1of bacterial cell suspension but were higher than 107 cfu mL−1. Further observations showed that conidial germination and appressorial formation ofBgtwere retarded by spraying E1R-j 24 h beforeBgtinoculation. Compared with the water check, conidial germination and appressorial formation were decreased by 43.3% and 42.7%, respectively. In the treatment with E1R-j, the number of houstoria significantly reduced and the speed of mycelial extension was slowed down in the wheat leaves. Scanning electron microscopy observation revealed that E1R-j significantly suppressed the conidial germination and caused rupture and deformation of germ tubes. On the surface of wheat leaves, mycelia and conidiophores became shrinking.

Factors Affecting the Persistence of Salmonella During the Processing of Poultry

Bacteria, including Salmonella, have been shown to attach firmly to poultry skin and meat. Neither fimbriae, flagella, nor electrostatic attraction seem to play a significant role in the mechanism of attachment. Bacterial cells (95%) were shown to be initially entrapped in a water film on the skin, then to migrate to the skin with prolonged immersion in a bacterial cell suspension. Using electron microscopy it was shown that bacteria appear to be entrapped in ridges and crevices which become more pronounced in the skin and muscle following water immersion. This may make bacteria on carcasses inaccessible to bactericides. It was shown that bacteria are firmly attached to poultry skin before broilers arrive at the plant and that high numbers are still recovered after 40 consecutive whole carcass rinses of a single carcass. It was further shown that Salmonella are not always recovered in the first whole carcass rinse and that this method of sampling could result in false negative reports for Salmonella incidence.