Pichia culture in flask - cover with cheese cloth or gauze? (Jul/14/2008 )

I'm new in Pichia culture. While I was reading on the manufacturer's protocol, it suggests us to induce Pichia with methanol in a flask covered with two layer of cheese cloths or gauze. My question here is by just two layer of cheese cloths or gauze, can my Pichia culture stay away from contaminants, such as other bacteria? How about using cotton, will it affect the oxigen ventilation?

Really hope that some can help me out here, thanks.

-kuahmk-

QUOTE (kuahmk @ Jul 14 2008, 11:51 AM)

I have used wads of cotton wool that were loosely covered with aluminium foil. That worked

-aspergillie-

Do it the old way = cover a chunk of cotton large enough to plug the flask with cheesecloth and sterilize it inserted into the medium containing flask. This practice maintains sterility and allows better air flow than aluminum foil. Microbiologists classically plugged both flasks and tube cultures in this manner.

But why not use a screw top flask?

-jorge1907-

QUOTE (jorge1907 @ Jul 15 2008, 11:52 AM)

But it is important for safety reasons that during the methanol induction, the methanol doesn't vaporizes into the rooms were people are working.

-aspergillie-

give me a break - the amount of methanol volatilizing from a few flasks is de minimus.

-jorge1907-

Hi

Thanks for your reply, jorge1907 and aspergillie. I think I will try to use the 'old method'.

MK

-kuahmk-

Hi
I used the 2 Litre full baffled Tunair flasks with DryGauze caps (I think this is just some sort of fibreglass) , can get from sigma, pichia grew very well in these with around 160rpm shaking and some antifoam 204, also from sigma.
cheers
mike

-mjf-