Poster Presentation Australian Microbial Ecology 2017

Plastic Packaging Surfaces as Microbial Niche for Coagulase Negative Staphylococci (#153)

Keka Sarkar 1 , Deepshikha Ghosh 1 , Paramita Mondal 1 , Rajat Banerjee 1 , Sumana Chatterjee 2
  1. Dr. B. C. Guha Centre for Genetic Engineering and Biotechnology, University of Calcutta, Kolkata, West Bengal, India
  2. Department of Chemistry, Basanti Devi College, Kolkata, West Bengal, India

Indiscriminate and rampant use of polyethylene as packaging material makes it a formidable pollutant to tackle. Without proper means of disposal, accumulation of plastic waste threatens the terrestrial and marine ecosystems. Coagulase negative Staphylococci are known to have a strong affinity for polymeric surfaces where they grow as biofilm1. This propensity of Coagulase negative staphylococci has been exploited by culturing them with commercially available plastic sheets that are used as packaging material. A strain of Staphylococcus epidermidis2 designated as BP/SU1 and a strain of Staphylococcus haemolyticus3 designated as BP/SU2 are studied in terms of their capacity to adhere, colonize and grow as biofilm. Both strains are environmental isolates. Adherence of bacteria is quantitatively measured by crystal violet staining followed by de staining with 33% glacial acetic acid and spectrophotometrically recording the absorbance of the washed solution at 570 nm. The biofilm architecture and the fate of the substrate is visualised through scanning electron microscope. Hydrophobicity of polyethylene makes it inaccessible to most microorganisms but both BP/SU1 and BP/SU2 can overcome this barrier and associate intimately with the different polyethylene samples used in this study. We have observed that BP/SU2 is more hydrophobic than BP/SU1 and its affinity towards polyethylene is greater than that of BP/SU1. Also, BP/SU2 forms a much more extensive and robust biofilm on plastic samples than BP/SU1. Recycled and biodegradable samples are favoured by the bacteria over virgin samples. Numerous studies have reported that biofilm formation is a prerequisite to biodegradation4. This enables the microorganisms to utilize a non soluble substrate. Establishing a biofilm involves multiple stages where adhesion is the first step and hydrophobic interactions play an important role5. This study demonstrates that adherence is governed by surface properties of the bacterial cell wall and the polymer upon which it is adhering. Thus, simultaneously manipulating the microorganisms in terms of the various factors that favour biofilm formation as well as conditioning the surface properties of the polymer primes it for biodegradation.

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