Meeting with Prem and Veeral - 2
| Date | |
|---|---|
| Department | GeneralHPWet Lab |
| Description | Asking cyanobacteria specific questions |
| HP sub-branch | |
| Links/media | |
| Participants | |
| Property | |
| Property 1 | |
| Property 2 | |
| Type | Meetings |
- Oxygen evolved by cyanobacteria is used by photorespiration
- When cyanobacteria are grown under low light and more CO2, less oxygen evolved as more goes into photorespiration?
- When supplied with 2% CO2 cylinders etc, the remaining gas it contains is zero air, comprised of mainly inert nitrogen. S elongatus cant fix atmospheric nitrogen and utilised dissolved forms of nitrogens in the medium, so nitrate nutrients will be contained in the medium itself, so cyanobacteria can grow in anaerobic conditions, it shouldn't be a problem if we were to even remove O2 from the set up through reducing agents, unless the agents directly harm the cyanobacteria
- methods of cultivation:
- photobioreactor - can regulate light, temperature, CO2 input etc. culture will be completely closed?
- incubator with co2 input - can hook up a cylinder to it, will have to plug flasks with cotton, CO2 can diffuse into flasks from chambers through the cotton plug, will have to strap on lights to set up
- incubator without co2 input - can't hook up a cylinder to it, will probably have to add bicarbonate for additional CO2 input, can back-calculate CO2 equivalent based on bicarbonate dissolved into medium, will have to strap on lights to the medium
- aquarium - very little control over culture, can be set up on a bench, bubbler to aerate it well, no cylinders can be attached, susceptible to contamination, it is a pond crash system - Himadri Pakrasi has work on this
- Get regulatable light sources and photometers/lux meter from phy dept? ask Dube or Atikur
- they get CO2 cylinders from Medgas
- Under ambient conditions PCC11801 can survive in culture for 15-16 days, with CO2 supply they can survive for longer
- PCC11801 can survive upto 10% CO2 concentration
- If you are growing cyanobacteria on flue gas, other compounds in the gas could harm the bacteria and we might have to clean the gas first, we could see whether it is economical to clean the gas first before supplying it to cyanobacteria
- Volumetric assays can be done to measure dissolved O2, most O2 measurements in cyanobacteria are done in terms of photosynthetic efficiency
- Weak promoters for cscB makes transformation easier and don't hamper membrane integrity but if literature is suggesting that strong promoters like cpc560 or lacUV work then we could use the same
- Use a constitutively expressed weak promoter or a strong inducible promoter
- LacUV is stronger than cpc560? Veeral: go for lac! Prem: but IPTG is expensive so you might not want to use IPTG inducible promoters, and instead use light or CO2 induced promoters or repressors under high light or CO2 exposure (what is the logic for repression at high light and CO2?)
- Annesha Sengupta has a paper reviewing promoters that we should check out
- The reason why Lin (2020) has such a high volumetric productivity is probably because of the culture conditions and maybe due to the promoter - lacUV might be even stronger than cpc560
- sucrose accumulation occurs during day time so it makes sense to grow cyanobacteria under continuous light conditions, however if you want to grow it in outdoor open tanks then you need to look into the diurnal cycle conditions
- Veeral said he will share papers on membrane inegrity, cscB directionality (in cyanobacteria it acts as symporter, sucrose transported along with H+ in the H+ gradient, but in E coli this might not be the case, the internal pH of E coli would be lower than the surrounding medium, so would it be an antitransporter in this case?), promoters - CyanoGate