Screening, Identification and Degradation Characteristic of Polystyrene Degrading Bacteria

doi:10.12422/j.issn.1672-6952.2024.01.003

Abstract

Abstract:

Pollution caused by petroleum?based plastic products has become a problem that is difficult for human beings to solve, and the existing treatment methods are both energy?consuming and easy to cause secondary pollution. The study found that the bacteria that degrade plastic in the intestines of Galleria mellonella (Lepidoptera: Pyralidae) larvae can effectively accelerate the degradation of plastics. This experiment uses polystyrene (PS) packaging boxes, which are common in life, as the only food source to feed the larvae of the large wax borer, enriching the PS?degrading bacteria in the intestines of the G. mellonella larvae. After dissection, culture, and isolation, four strains were obtained: PD?1, PD?2, PD?3 and PD?4. The degradation capacity of MSM culture medium with PS film as the only carbon source was inoculated with each strain, and the degradation rate of PD?1 on PS film was the highest, which was 1.8%. PD?1 was observed by strain morphology, physiological biochemical determination and phylogenetic tree construction, and it was identified as Enterobacter colebella (Klebsiella). Meanwhile, the method of UV and nitric acid pretreatment of PS film were used to improve the degradation rate of the strain, and the results showed that the weight loss rate of PD?1 degradation of nitric acid?treated PS film was improved, which was 2.5%, while the UV group was 0.8%, indicating that PS film was more easily degraded by PD?1 after nitric acid treatment.

Key words: Galleria mellonella, Polystyrene degrading bacteria, Identification, Degradation rate

摘要：

石油基废弃塑料造成的环境污染已成为人类难以解决的问题，而现有的处理方式既耗能又容易造成二次污染。研究发现，大蜡螟幼虫肠道内存在降解塑料的细菌，可有效加快塑料的降解，分离纯化其肠道内菌株具有极高的研究价值。因此，使用生活中常见的聚苯乙烯（PS)包装盒作为唯一食物来源喂食大蜡螟幼虫，富集大蜡螟幼虫肠道内的PS降解菌；经解剖、培养、分离，最终获得4株菌株（PD?1、PD?2、PD?3和PD?4）。将各菌株接种至以PS薄膜为唯一碳源的基础盐培养基（MSM培养基）并测定了其降解率。结果表明，PD?1对PS薄膜降解率最高，为1.8%。对PD?1进行菌株形态观察、生理生化测定及系统发育树构建，鉴定PD?1为肠杆菌科克雷伯氏菌属（Klebsiella）。同时，采用紫外或硝酸对PS薄膜进行了预处理，以期提高菌株降解率。结果表明，PD?1降解硝酸预处理的PS薄膜的降解率为2.5%，而对紫外预处理的PS薄膜的降解率为0.8%，PS薄膜经硝酸预处理后更易被PD?1降解。

关键词: 大蜡螟, 聚苯乙烯降解菌, 鉴定, 降解率

CLC Number:

TQ319

Zheyu PANG, Jingjing ZHAO, Tianli WAN, Jiajun LI, Lingsen YANG, Siyu ZHOU, Tingting SU. Screening, Identification and Degradation Characteristic of Polystyrene Degrading Bacteria[J]. Journal of Liaoning Petrochemical University, 2024, 44(1): 15-20.

庞哲宇, 赵晶晶, 万天丽, 李佳俊, 杨凌森, 周思宇, 苏婷婷. 聚苯乙烯降解菌的筛选鉴定及降解特性研究[J]. 辽宁石油化工大学学报, 2024, 44(1): 15-20.

Figures/Tables 8

Fig.1 Degradation rate of PS film of four strains

Table 1 Characteristics of physiological and biochemical reactions

反应物	结果	反应物	结果
葡萄糖	+	棉子糖	+
蔗糖	+	丙酸盐	-
鼠李糖	+	甲基红	-
纤维二糖	+	接触酶	+
乳糖	+	酪氨酸	-
木糖	+	V⁃P	+
淀粉	+	明胶	-
麦芽糖	+

Fig.2 Colony morphology and electron microscopy of strain PD?1

Fig.3 Neighbor?joining phylogenetic tree of strain PD?1 based on the 16S rRNA gene

Fig.4 Electron microscope observations of PS film and bacteria

Fig.5 Water contact angle analysis results and cap film test results

Fig.6 Changes in atomic composition of the PS film surface after treatment with PD?1

Table 2 Degradation rate of PS films after pretreatment with ultraviolet light and nitric acid

类别	m_降解前/mg		m_降解后/mg		降解率/%
类别	紫外光预处理	硝酸预处理	紫外光预处理	硝酸预处理	紫外光预处理	硝酸预处理
对照组	112.2	74.7	111.5	74.3	0.6	0.5
PD⁃1单菌株组	112.3	74.1	111.4	72.2	0.8	2.5
混合菌组	112.2	73.1	110.1	71.9	1.9	1.6

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