Abstract
BackgroundThe excessive use of polystyrene as a packaging material has resulted in a rise in environmental pollution. Polystyrene waste has continually increased water pollution, soil pollution and the closing of landfill sites since it is durable and resistant to biodegradation. Therefore, the challenge in polystyrene disposal has caused researchers to look for urgent innovative and eco-friendly solutions for plastic degradation. The current study focuses on the isolation and identification of bacteria produced by the larvae of beetle Tenebrio molitor (yellow mealworms), that enable them to survive when fed with polystyrene foam as their sole carbon diet.Materials and methodsThe biodegradation of polystyrene by Tenebrio molitor was investigated by breeding and rearing the mealworms in the presence and absence of polystyrene. A comparison was made between those fed with a normal diet and those fed on polystyrene. The mealworms which were fed with polystyrene were then dissected and the guts were collected to isolate and identify the bacteria in their guts. The viability and metabolic activity of the isolates were investigated. The polymerase chain reaction (PCR) followed by sequencing was used for molecular identification of the isolates. The PCR products were directly sequenced using Sanger’s method and the phylogenetic tree and molecular evolutionary analyses were constructed using MEGAX software with the Neighbour Joining algorithm. The evolutionary distances were computed using the Maximum Composite Likelihood method.ResultsThe decrease in mass of the polystyrene as feedstock confirmed that the mealworms were depending on polystyrene as their sole carbon diet. The frass egested by mealworms also confirmed the biodegradation of polystyrene as it contained very tiny residues of polystyrene. Three isolates were obtained from the mealworms guts, and all were found to be gram-negative. The sequencing results showed that the isolates were Klebsiella oxytoca ATCC 13182, Klebsiella oxytoca NBRC 102593 and Klebsiella oxytoca JCM 1665.ConclusionKlebsiella oxytoca ATCC 13182, Klebsiella oxytoca NBRC 102593 and Klebsiella oxytoca JCM 1665 maybe some of the bacteria responsible for polystyrene biodegradation.
Highlights
The excessive use of polystyrene as a packaging material has resulted in a rise in environmental pollution
The decrease in mass of the polystyrene as feedstock confirmed that the mealworms were depending on polystyrene as their sole carbon diet
The sequencing results showed that the isolates were Klebsiella oxytoca ATCC 13182, Klebsiella oxytoca NBRC 102593 and Klebsiella oxytoca JCM 1665
Summary
The excessive use of polystyrene as a packaging material has resulted in a rise in environmental pollution. The current study focuses on the isolation and identification of bacteria produced by the larvae of beetle Tenebrio molitor (yellow mealworms), that enable them to survive when fed with polystyrene foam as their sole carbon diet. The excessive use of durable and degradation-resistant synthetic polymers such as polystyrene as a packaging material has resulted in a rise in environmental pollution [1]. Biodegradation of polystyrene by mealworms has been confirmed by academic researchers from different countries who concluded that yellow mealworms can survive when fed with polystyrene foam as their sole carbon diet [8]. The current study focuses on the isolation and identification of bacteria produced by the larvae of beetle Tenebrio molitor, which enable them to survive when fed with polystyrene foam. The gut of the larvae of Tenebrio molitor may contain microorganisms that degrade polystyrene, yellow mealworms are economically among the most important species that could be used for biodegradation of polystyrene [8, 9]
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