Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial Design
Microplastics (MP) are a global environmental problem because they persist in the environment for long periods of time and negatively impact aquatic organisms. Possible solutions for removing MP from the environment include biological processes such as bioremediation, which uses microorganisms to re...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-10-01
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| Series: | Polymers |
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| Online Access: | https://www.mdpi.com/2073-4360/14/20/4299 |
| _version_ | 1797470152408694784 |
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| author | Martina Miloloža Šime Ukić Matija Cvetnić Tomislav Bolanča Dajana Kučić Grgić |
| author_facet | Martina Miloloža Šime Ukić Matija Cvetnić Tomislav Bolanča Dajana Kučić Grgić |
| author_sort | Martina Miloloža |
| collection | DOAJ |
| description | Microplastics (MP) are a global environmental problem because they persist in the environment for long periods of time and negatively impact aquatic organisms. Possible solutions for removing MP from the environment include biological processes such as bioremediation, which uses microorganisms to remove contaminants. This study investigated the biodegradation of polystyrene (PS) by two bacteria, <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i>, isolated from environmental samples in which MPs particles were present. First, determining significant factors affecting the biodegradation of MP-PS was conducted using the Taguchi design. Then, according to preliminary experiments, the optimal conditions for biodegradation were determined by a full factorial design (main experiments). The RSM methodology was applied, and statistical analysis of the obtained models was performed to analyze the influence of the studied factors. The most important factors for MP-PS biodegradation by <i>Bacillus cereus</i> were agitation speed, concentration, and size of PS, while agitation speed, size of PS, and optical density influenced the process by <i>Pseudomonas alcaligenes</i>. However, the optimal conditions for biodegradation of MP-PS by <i>Bacillus cereus</i> were achieved at <i>γ</i><sub>MP</sub> = 66.20, MP size = 413.29, and agitation speed = 100.45. The best conditions for MP-PS biodegradation by <i>Pseudomonas alcaligenes</i> were 161.08, 334.73, and 0.35, as agitation speed, MP size, and OD, respectively. In order to get a better insight into the process, the following analyzes were carried out. Changes in CFU, TOC, and TIC concentrations were observed during the biodegradation process. The increase in TOC values was explained by the detection of released additives from PS particles by LC-MS analysis. At the end of the process, the toxicity of the filtrate was determined, and the surface area of the particles was characterized by FTIR-ATR spectroscopy. Ecotoxicity results showed that the filtrate was toxic, indicating the presence of decomposition by-products. In both FTIR spectra, a characteristic weak peak at 1715 cm<sup>−1</sup> was detected, indicating the formation of carbonyl groups (−C=O), confirming that a biodegradation process had taken place. |
| first_indexed | 2024-03-09T19:32:42Z |
| format | Article |
| id | doaj.art-70138b2313f749f29ce1749b7ff6caa2 |
| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-03-09T19:32:42Z |
| publishDate | 2022-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Polymers |
| spelling | doaj.art-70138b2313f749f29ce1749b7ff6caa22023-11-24T02:06:45ZengMDPI AGPolymers2073-43602022-10-011420429910.3390/polym14204299Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial DesignMartina Miloloža0Šime Ukić1Matija Cvetnić2Tomislav Bolanča3Dajana Kučić Grgić4Faculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, 10 000 Zagreb, CroatiaFaculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, 10 000 Zagreb, CroatiaFaculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, 10 000 Zagreb, CroatiaFaculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, 10 000 Zagreb, CroatiaFaculty of Chemical Engineering and Technology, University of Zagreb, Trg Marka Marulića 19, 10 000 Zagreb, CroatiaMicroplastics (MP) are a global environmental problem because they persist in the environment for long periods of time and negatively impact aquatic organisms. Possible solutions for removing MP from the environment include biological processes such as bioremediation, which uses microorganisms to remove contaminants. This study investigated the biodegradation of polystyrene (PS) by two bacteria, <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i>, isolated from environmental samples in which MPs particles were present. First, determining significant factors affecting the biodegradation of MP-PS was conducted using the Taguchi design. Then, according to preliminary experiments, the optimal conditions for biodegradation were determined by a full factorial design (main experiments). The RSM methodology was applied, and statistical analysis of the obtained models was performed to analyze the influence of the studied factors. The most important factors for MP-PS biodegradation by <i>Bacillus cereus</i> were agitation speed, concentration, and size of PS, while agitation speed, size of PS, and optical density influenced the process by <i>Pseudomonas alcaligenes</i>. However, the optimal conditions for biodegradation of MP-PS by <i>Bacillus cereus</i> were achieved at <i>γ</i><sub>MP</sub> = 66.20, MP size = 413.29, and agitation speed = 100.45. The best conditions for MP-PS biodegradation by <i>Pseudomonas alcaligenes</i> were 161.08, 334.73, and 0.35, as agitation speed, MP size, and OD, respectively. In order to get a better insight into the process, the following analyzes were carried out. Changes in CFU, TOC, and TIC concentrations were observed during the biodegradation process. The increase in TOC values was explained by the detection of released additives from PS particles by LC-MS analysis. At the end of the process, the toxicity of the filtrate was determined, and the surface area of the particles was characterized by FTIR-ATR spectroscopy. Ecotoxicity results showed that the filtrate was toxic, indicating the presence of decomposition by-products. In both FTIR spectra, a characteristic weak peak at 1715 cm<sup>−1</sup> was detected, indicating the formation of carbonyl groups (−C=O), confirming that a biodegradation process had taken place.https://www.mdpi.com/2073-4360/14/20/4299microplasticspolystyrene<i>Bacillus cereus</i><i>Pseudomonas alcaligenes</i>Taguchi designbiodegradation |
| spellingShingle | Martina Miloloža Šime Ukić Matija Cvetnić Tomislav Bolanča Dajana Kučić Grgić Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial Design Polymers microplastics polystyrene <i>Bacillus cereus</i> <i>Pseudomonas alcaligenes</i> Taguchi design biodegradation |
| title | Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial Design |
| title_full | Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial Design |
| title_fullStr | Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial Design |
| title_full_unstemmed | Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial Design |
| title_short | Optimization of Polystyrene Biodegradation by <i>Bacillus cereus</i> and <i>Pseudomonas alcaligenes</i> Using Full Factorial Design |
| title_sort | optimization of polystyrene biodegradation by i bacillus cereus i and i pseudomonas alcaligenes i using full factorial design |
| topic | microplastics polystyrene <i>Bacillus cereus</i> <i>Pseudomonas alcaligenes</i> Taguchi design biodegradation |
| url | https://www.mdpi.com/2073-4360/14/20/4299 |
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