I am working on fungal degradation of polyethylene. I have placed polyethylene powder in mineral salt medium and subsequently placed my fungal isolates. My question is do I really have to put them in a shaker or can I just leave them static with regular shaking, let us say daily, for aeration? Will continuous shaking, in a shaker, disrupts degradation processes?
I think it would have been better to put the sample in a shaker at low speed (between 65 and 90) for better growth and faster degradation.
Dear Den,
Generally fungi have two phases. One is prostrate, which is secretory and more metabolically active. Second is the erect (aerial), which forms reproductive structures. If the culture remain left for some times, fungi start growing on surface. However, more metabolites are secreted only by submerged mycelia, which, then mixed to medium and participate in reactions. Hence, continuous agitation is required to check the aerial growth and for maximum activity.
For that, you may use low rpm as suggested by Prof Tarafdar.
Kind regards.
Hi: Yes, shaking continuously will constantly break the mycelia of the fungus and that induce the fungal to grow.
Thanks everyone for your answers. But don't you think continuous shaking will disrupt contact between fungi and plastic powder that will subsequently reduce the biodegradation rate? I am thinking of only shaking it every once in a while, let's say every 5 hours, since one of the limitation is the availability of shaker since I am screening lots of fungal isolates.
Hi Jo,
On the contrary, shaking will increase mass transfer by improving contacts between polyethylene particles and biocatalyzer thus biodegradation will be higher. If the substrate were a soluble one still cultivation could be work (though rates and yields are low). The shaking velocity depends on: 1) the type of shaker (reciprocating or orbital); 2) fungal strain (does it grow as mycelial mats or pellets?). According to the description of your experiment polyethylene is the only carbon source then you have to consider that this substance is not water soluble and very reduced, thus you need: 1) high mass transfer rates; 2) high oxygen input to the system. I would use either baffled flasks in an orbital shaker or normal flasks in a reciprocating shaker at no less than 150 rpm.
I hope this will help you.
Best wishes
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