Pellicle formation of MR-1

ABSTRACT: Shewanella oneidensis is an important model organism for bioremediation studies because of its diverse respiratory capabilities. In recent years, biofilm development of S. oneidensis has been extensively studied because it is essential to reduce solid metals. As a special form of biofilm, however, pellicles are largely overlooked. The goal of this work was to understand requirements of S. oneidensis pellicle formation and the molecular basis of pellicle formation. We demonstrated that successful pellicle formation and survival was likely to require the threshold level of cell density and higher concentration of oxygen. Proteinase K and EDTA were potent pellicle disrupter. DNA microarray experiments were used to study the gene expression profile of young air–liquid interface pellicle relative to planktonic cells, which indicated that the air–liquid interface pellicle was more metabolically active than the planktonic cells. Most notably, consistently up-regulation of iron or heme uptake and transportation proteins was observed in the S. oneidensis MR-1 pellicle. However, neither the hmuT nor hugA heme transport mutant was defective in pellicle formation. An examination of the influence of several metal cations on the anti-pellicle activity of EDTA showed that Ca (II), Mn(II), Cu(II), and Zn(II) fully protected S. oneidensis MR-1 pellicle against EDTA treatment while additional of iron enabled the initiation of pellicle formation but maturation was significantly impaired. Collectively, iron was less important than other metals with respect to pellicle formation in S. oneidensis. A fresh colony grown overnight on a LB plate was used to inoculate 50 ml LB and incubated in a shaker (200 rpm) to an OD600 of 0.8 at the room temperature. This culture was then diluted 500-fold with fresh LB, resulting in the starting cultures. Aliquots of 30ml starting cultures were transferred to 50-ml Pyrex beakers and allowed to develop pellicles at the room temperature. When a complete but thin (young pellicle) at the interface were formed (about 30h hours), planktonic culture and pellicle were separated and applied to centrifugation at 8000 rpm for 3 min at room temperature. 3 parallel starting cultures were used and 3 samlpes of pellicle cells or planktonic cells were collected at 30h. RNA from the pellicle cells was fluorescently labeled with Cy3, and that from the planktonic was labeled with Cy5.

ORGANISM(S): Shewanella oneidensis MR-1

SUBMITTER: Yili Liang 

PROVIDER: E-GEOD-14331 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress