Determination of the biodegradability of chitosan utilizing the most probable number technique

Wender Cardoso Silva,Vivian Machado Benassi,Juan Pedro Bretas Roa,Ilva De Fátima Souza,David Lee Nelson,Arlete Barbosa Dos Reis,Paulo Henrique Graziotti

doi:10.4025/actascibiolsci.v42i1.52965

Wender Cardoso Silva, Vivian Machado Benassi + Show 5 more

Open Access

https://doi.org/10.4025/actascibiolsci.v42i1.52965

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Abstract

The present work aimed to evaluate the degradability of the chitosan polymer by soil microorganisms. This evaluation was accomplished using the Most Probable Number (MPN) method by plating in drops so that soil microorganisms capable of degrading the polymeric material could be quantified. Soil samples diluted in three specific culture media for each type of microorganism were plated – bacteria, fungi and actinobacteria – and they were maintained at 28°C for seven days to determine the growth rate of fungi and actinobacteria, and for 48 hours for the development of bacteria. Significant differences in the MPN of actinobacteria relative to the other groups analyzed were observed. Thus, the method used was effective for determining the degradability of the chitosan biopolymer when observing the development of microorganisms subjected to the replacement of the carbon source by the addition of 2% w v-1 of the chitosan biopolymer to the culture medium. The formation of clear regions around the microbial colonies was a strong indicator of biodegradation.

Highlights

Many studies focus on the analysis of biodegradation of polymers, that is, analysis of the degradation of polymeric materials through the action of living organisms (Fechine, 2013)
The present study presents an alternative method for evaluating the biodegradability of chitosan biopolymer via the determination of the most probable number of soil microorganisms through analyses of the soil moisture content, experiments of quantification of microorganisms using specific culture media for bacteria, fungi and actinobacteria and replacement of the carbon source by a 2% (w v-1) chitosan solution
Biodegradability tests were carried out on soil using the Most Probable Number (MPN) technique to understand the degradability of the chitosan polymer in relation to the availability of the carbon source

Summary

Introduction

Many studies focus on the analysis of biodegradation of polymers, that is, analysis of the degradation of polymeric materials through the action of living organisms (Fechine, 2013). The determination of methods that allow the assessment of the biodegradability of a polymer and the class of microorganisms capable of degrading them can contribute to studies that guide the disposal of plastic materials. The rhizosphere, a thin area of soil around the roots that receives carbon exudation from plants, represents a region of intense competition for available carbon and nutrients between surface reactive particles and soil microorganisms (Merino, Nannipieri, & Matus, 2015). The rhizosphere region can be directly affected by the availability of nutrients and the quality of the substrate (Murphy, Writer, McCleskey, & Martin, 2015)

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