Part:BBa_K1166000 Bba_K1166000 under different hypoxia conditions

Objective

We aimed to characterize the part sent by de Monterrey Team which is a GFP under a hypoxia inducible promoter, cloned in a replicative plasmid (Bba_K1166000). For that purpose we transformed E. coli DH5α with plamid Bba_K1166000 and conducted 2 different assays described below using this strain.

Experiment 1: hypoxia induced by anaerobiosis boxes

Method

A 5ml culture of E. coli DH5α carrying the plasmid Bba_K1166000 in LB medium was grown for 16 h in aerobiosis, 1 ml was centrifuged and the pellet was kept frozen in order to use it as fluorescence control without induction. The rest of the culture was incubated for 20 h under anaerobic and microanaerobic conditions using hermetic boxes and GENbox aner and GENbox microanaer systems (bioMérieux), respectively, without shacking at 37°C. GENbox aner and GENbox microanaer systems are based on a chemical compound that traps oxygen. One ml of each condition was centrifuged and the pellets frozen. Finally, fluorescence (excitation: 475 nm) was measure and normalized by OD600nm. Both treatments were performed in duplicate.

Results

Experiment 2: hipoxia induced in a microscope slide sealed

Method

An E. coli DH5α carrying the plasmid Bba_K1166000 was grown under aerobic conditions overnight. Then, 10ul of this culture was placed in a microscope slide, covered with a coverslip and sealed with nail enamel (similar as usually performed to induce hypoxia in plant cells).

Afterwards, pictures of bacteria were taken in a fluorescence microscope every 15 min for 1 h. The first picture was taken immediately after sealing. Every picture was taken using the same exposition time (1/5 sec). Unfortunately, a lot of bleaching was observed. To avoid this, the field was changed before taking each photo. From 0 min, bacteria exhibited green fluorescence, however no significant induction can be observed in the time points analyzed (15, 30, 45 and 60 min).

Results