Impact of Iron Availability on <i>Bacillus amyloliquefaciens</i> Growth

Abstract

Bacillus amyloliquefaciens is a biocontrol agent whose genome has been sequenced. Within the genome of B. amyloliquefaciens are genes associated with iron chelation, but these genes are not found within all sequenced strains. The impact of iron availability on the B. amyloliquefaciens physiology was examined in this study. B. amyloliquefaciens ATCC 23843 was cultured under ironreplete and iron-deplete conditions for 48 hours, at 37˚C. Final growth yields were dependent on iron concentration. Cultures grown in the absence of detectable iron were restricted in growth, but reached their highest yields at 48 hours. Iron restriction was confirmed by the presence of iron chelators in the filtrates. In contrast, B. amyloliquefaciens ATCC 23843 cultures grown with ferric ammonium citrate as the iron source research reached the highest yields at 24 hours. Iron chelator production was not detected in the ferric ammonium samples. A significant decrease in turbidity was observed for these cultures, which coincided with elevated spore production in B. amyloliquefaciens ATCC 23843. A decrease in turbidity was also observed on blood agar, where hemolysis was readily evident. We propose that iron impacts numerous physiological responses and further studies will elucidate the complex regulatory mechanisms governed by iron availability.

Siderophore Production by Rhizosphere Inhabiting Bacteria and Fungi

“…In the FeCl 3 test, the spectral analyses of Bacillus MAP3 ferrated siderophores, show a maximum absorbance at 495,which confirm the catecolate nature of the siderophores (Fig. 4-I), this result was consonance with a previous study (Clark et al, 2014), that indicated the predominate of catecholate type siderophores in the Bacillus genus, specifically Bacillibactin catecolate type siderophores. However, in the study of (Murugappan et al, 2011) they reported that its impossible to characterize the siderophores based on the bacteria species, because siderophores of varying nature have been produced by the same genus.…”