filters - sterile or not?
- Thread starter aky
- Start date
BIGGSHOT94
New member
No filters don't have to be sterile. As long as you're heating your products you shouldn't have to worry as much about the sterility of it.
You can buy sterile filters but like you said they're more expensive and they both do the same job.
You can buy sterile filters but like you said they're more expensive and they both do the same job.
I'll post this one more time. plese read
BA is only effective against Gram-positive bacteria. it is not effective against gram-negative bacteria. endotoxins are contained in the membrane walls of gram-negative bacteria and this can lead to sickness or even death. Filter sterilization is useful for sterilizing heat labile liquids. The filters have pores of specific sizes down to 0.2 micron in diameter.
Three types of filters
Depth filters - routine filters made of paper, asbestos or glass fibers. Just a mat of the fibers.
Membrane filters - cellulose acetate or cellulose nitrate materials. Contains lots of tiny holes that act live sieves to retain bacteria.
Nucleopore filters - polycarbonate filters. Very uniform pore sizes. Great for microscopy work since the filters are flat in nature.most bacteria is trapeed by .45 micron filters. the ones that can make it thru are killed by heat. The autoclave - 15 lbs/sq. inch which yields a temperature of 121 oC for 10 -15 minutes.
Not all materials can withstand autoclaving, e.g., milk, so they are pasteurized. Pasteurization is a mild heating to kill sensitive spoilage bacteria. Milk is heated to 71oC for 15 seconds in a continuous flow system. 250f is what is generally used to be on the safe side for home labs. do not fool your selves into thinking that BA will protect you from all infections. endotoxins are no joke. ever hear of meningitidis?
BA is only effective against Gram-positive bacteria. it is not effective against gram-negative bacteria. endotoxins are contained in the membrane walls of gram-negative bacteria and this can lead to sickness or even death. Filter sterilization is useful for sterilizing heat labile liquids. The filters have pores of specific sizes down to 0.2 micron in diameter.
Three types of filters
Depth filters - routine filters made of paper, asbestos or glass fibers. Just a mat of the fibers.
Membrane filters - cellulose acetate or cellulose nitrate materials. Contains lots of tiny holes that act live sieves to retain bacteria.
Nucleopore filters - polycarbonate filters. Very uniform pore sizes. Great for microscopy work since the filters are flat in nature.most bacteria is trapeed by .45 micron filters. the ones that can make it thru are killed by heat. The autoclave - 15 lbs/sq. inch which yields a temperature of 121 oC for 10 -15 minutes.
Not all materials can withstand autoclaving, e.g., milk, so they are pasteurized. Pasteurization is a mild heating to kill sensitive spoilage bacteria. Milk is heated to 71oC for 15 seconds in a continuous flow system. 250f is what is generally used to be on the safe side for home labs. do not fool your selves into thinking that BA will protect you from all infections. endotoxins are no joke. ever hear of meningitidis?
TxLonghorn
Co-Founder
chatbear said:
Agreed.
chatbear said:
the bacteria that is small enough to make it thru a .45 filter is easily killed by 250f heat. there arent many that are that small though. also just because the heat kills it doesnt mean that it is removed. just means it is dead. its still in there. pesky endotoxins.
