Hi Donghan

I think the following article is useful.

https://dx.doi.org/10.1186%2Fs13568-018-0536-0

Influence of culture media, pH and temperature on growth and bacteriocin production of bacteriocinogenic lactic acid bacteria

All the best

@Negar Bagheri

Thank you. I found your article useful.

I think I should consider some other parameters aside from pH. perhaps i should incubate them in a room temeprature.

have a good day! ;)

Make cell suspension 2% of LAB and add it to flask of 100 ml broth MRS shake well and incubate at the optimum temperature about 32 C° for 48 h, the growth well appear as pellets.

Thanks to your kind answers!

I have tried 5% subculturing and yes it did work. I saw some tiny pellets at the bottom of conical tube.

thanks to all people who helped me to find out some clue.

God Bless!

I've been through the same situation last week...After measuring OD, I incubated 100uL in 4ml MRSB for 4h at 37°C, and when I went to centrifuge to collect the supernatant...no pellets! I will try incubating them for a longer time, but incubating for only for 4 hours is also a step to select the fastest and best producing latic acid strains...so this proof of concept will serve just to see if everything's okay with the medium and the protocol overall...

yes. after selecting some grown LAB, our lab draw a growth curve for that specific strain. in timely manner 1 2 4 8 12 24 48h. thou it seems lactobacilli groes faster in MRS than other genus LAB like Lactococcus. Enterococci.

We have never faced this situation. I suggest that you might look for the literature about L-cysteine supplement. It has positive effects on growth of lactic acid bacteria in MRS (solid or liquid media)

thanks for kind answers, I have tried inoculating 2%~5% sub culture and adjusted temperature to 25'C~30'C instead of usual 37'C and it worked perfectly!