I have read 'due to continuous subculture, the proteus may lose the fimbriae and stop swarming and lose its ability to form biofilm'. But my proteus isolate is still showing swarming motility, but no biofilm formation(earlier it was a strong biofilm former). Can anyone suggest the reason and help to solve the problem
Before you start your experiments, make many lyophils or glycerol stocks of your strain. You should transfer culture for 4-5 times only then again sub culture from stocks. This would take care of the change in genotype of the culture. Also do not keep your plates for long time in refrigerator discard within 4-5 days and sub culture from stocks again. This might look little daunting but it will go a long way in keeping the genetic integrity of your strain and thus reproducibility of your results. All the best.
My first question to you would be, to which type of isolate you are referring? Is it the one from the soil (free living) or the patient? The one from the patient under laboratory experimentation conditions could develop a new behavior because it undergo mutation due to the influence of exogenous factors. For the free living one, biofilm formation is a cooperative group behaviour that involves bacterial populations living embedded in a self-produced extracellular matrix, which involve a cell to cell communication mechanism (quorum sensing) that synchronizes gene expression in response to reactions to chemicals/ to the environment. it would appear that QS might coordinate the switch to a biofilm lifestyle but, negatively in your case to your isolate in the system. That means, there are many factors to be studied, which influence the changing of behavior of your isolate in which ever case would be.
Thank you for your comments.
My isolate is from a patient and it was a strong biofilm former for the past eight months. I have also tried from agar stabs, it is also showing very weak biofilm formation.
In this case, have you checked its hydrolyzing activity. Because, Proteus spp are well known for their high haemolytic activity. So, it may have changed its behavior to be more virulent.
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