Screening and identification of a polyurethane-degrading bacterium G-11 and its plastic degradation characteristics / 生物工程学报

Polyurethane (PUR) plastics is widely used because of its unique physical and chemical properties. However, unreasonable disposal of the vast amount of used PUR plastics has caused serious environmental pollution. The efficient degradation and utilization of used PUR plastics by means of microorganisms has become one of the current research hotspots, and efficient PUR degrading microbes are the key to the biological treatment of PUR plastics. In this study, an Impranil DLN-degrading bacteria G-11 was isolated from used PUR plastic samples collected from landfill, and its PUR-degrading characteristics were studied. Strain G-11 was identified as Amycolatopsis sp. through 16S rRNA gene sequence alignment. PUR degradation experiment showed that the weight loss rate of the commercial PUR plastics upon treatment of strain G-11 was 4.67%. Scanning electron microscope (SEM) showed that the surface structure of G-11-treated PUR plastics was destroyed with an eroded morphology. Contact angle and thermogravimetry analysis (TGA) showed that the hydrophilicity of PUR plastics increased along with decreased thermal stability upon treatment by strain G-11, which were consistent with the weight loss and morphological observation. These results indicated that strain G-11 isolated from landfill has potential application in biodegradation of waste PUR plastics.

Research progress on content and detection methods of microplastics/nanoplastics in biological samples / 环境与职业医学

Plastic products are widely used in various fields, and the discarded plastics in the environment can be degraded into microplastics (MPs) or even nanoplastics (NPs), which significantly increases the risk of organism exposure. MPs/NPs have been found in aquatic organisms, birds of prey, and even humans. The detection of plastic particles in biological samples is more complicated than that in environmental samples. Biological samples are mainly composed of various organic substances such as proteins and lipids, which makes the pretreatment process particularly critical. Effective detection and accurate quantification of MPs/NPs are crucial to health risk assessment. In this paper, the exposure levels and composition of MPs/NPs in different tissues and organs of the human body, aquatic organisms, and birds of prey were reviewed. The digestion of biological samples (acids, bases, enzymes, and hydrogen peroxide digestion protocols) and MPs/NPs identification methods (spectroscopy and chromatography) were compared and their advantages and disadvantages were assessed, providing a methodological basis for plastic exposure risk assessment and pollution control.

Consumo incidental de plástico y otros materiales antropogénicos por parte de Coragyps atratus (Bechstein, 1793) en un vertedero de basura de Ecuador / Incidental consumption of plastic and other anthropogenic materials by Coragyps atratus (Bechstein, 1793) in a garbage dump in Ecuador

Resumen En este estudio se analiza y discute la ingesta de plástico y otros materiales antropogénicos por parte de Coragyps atratus en un vertedero de residuos suburbano de Calceta, Provincia de Manabí, Ecuador. De un total de 112 egagrópilas analizadas, el 100% contenía materiales antropogénicos siendo los más conspicuos, diferentes tipos de plásticos y microplásticos, además de metales, vidrio, suelo y otros. Se discute y contrasta con la bibliografía la importancia relativa de los materiales antropogénicos encontrados, así como su potencial impacto en la especie y para el ser humano.

Abstract This study analyzes and discusses the ingestion of plastic and other anthropogenic materials by Coragyps atratus in a suburban waste dump in Calceta, Manabí Province, Ecuador. Of a total of 112 pellets analyzed, 100% contained anthropogenic materials, the most conspicuous being different types of plastics and microplastics, as well as metals, glass, soil, and others. The relative importance of the anthropogenic materials found is discussed and analyzed, same as their potential impact on the species and humanity.

Impacto colateral del COVID-19 en la salud ambiental derivado de la disposición inadecuada de mascarillas / Collateral impact of COVID-19 on environmental health derived from improper disposition of masks

El uso de mascarillas por parte de la población general como elemento de protección personal frente al COVID-19 se mantuvo en ascenso durante la primera mitad del 2020, en medio de constantes actualizaciones de la OMS acerca del público objetivo, su correcto uso y posibles beneficios, pero donde no se definieron protocolos para el manejo del desecho resultante. Durante el segundo semestre del 2020 la población mundial usaba diariamente 4.300 millones de mascarillas, de las cuales el 78,5% se descartaban de forma incorrecta, llegando a generar un volumen de 2,61 (2,26-2,94; IC=95%) millones de toneladas de desecho diseminadas en el medio ambiente. Los componentes plásticos incorporados en la fabricación de mascarillas como PP, PE y PET pueden tardar 400 años en degradarse en condiciones ambientales, fragmentándose paulatinamente en microplásticos, que afectan a la flora, fauna, agua y suelos de su entorno. Adicionalmente, algunos aditivos sintéticos antioxidantes (AO) usados en la fabricación de plásticos pueden retardar aún más las reacciones de degradación de las mascarillas descartadas hacia el ambiente, aumentando su daño potencial. Se calculó que 216,9 (188,5-245,3; IC=95%) toneladas de AO168, 190 (165,2-214,9; IC=96%) toneladas de AO168O y 442,7 (384,8-500,6; IC=95%) toneladas de AO1010 fueron expuestas al medio ambiente debido a la disposición incorrecta de mascarillas en la segunda mitad de 2020. Aunque la masa conjunta de estos componentes sintéticos sólo representa el 0,017% de las mascarillas desechadas en el mismo lapso, su concentración resulta suficiente para acrecentar el riesgo de daño al ambiente(AU)

The use of masks by the general population as an element of personal protection against COVID-19 continued to rise during the first half of 2020, amid constant updates from the WHO about the target audience, their correct use and possible benefits, but where no protocols were defined for the management of the resulting waste. During the second half of 2020, the world population used 4.3 billion masks daily, of which 78.5% were discarded incorrectly, generating a volume of 2.61 (2.26-2.94; IC = 95%) million tons of waste disseminated in the environment. The plastic components incorporated in the manufacture of masks such as PP, PE and PET can take 400 years to degrade under environmental conditions, gradually fragmenting into microplastics, which affect the flora, fauna, water and soils of their environment. Additionally, some synthetic antioxidant additives (OA) used in the manufacture of plastics can further delay the degradation reactions of discarded masks into the environment, increasing their potential damage. It was calculated that 216.9 (188.5-245.3; IC = 95%) tons of AO168, 190 (165.2-214.9; IC = 96%) tons of AO168O and 442.7 (384.8 -500.6; IC = 95%) tons of AO1010 were exposed to the environment due to the incorrect disposal of masks in the second half of 2020. Although the combined mass of these synthetic components only represents 0.017% of the masks discarded in the same period, its concentration is sufficient to increase the risk of damage to the environment(AU)

Isolation and characterization of a polyurethane-degrading bacterium / 生物工程学报

Biodegradation of polyurethane (PUR) pollutants by microorganisms has received widespread attention currently. Identification of microorganisms capable of efficiently degrading PUR plastics is a key point. In this study, a strain P10 capable of degrading PUR was isolated from the plastic wastes, and identified as a bacterium belonging to the genus of Brevibacillus based on colony morphology and 16S rDNA phylogenetic analysis. Brevibacillus sp. P10 was capable of degrading 71.4% of waterborne polyurethane (Impranil DLN) after 6 days growth in MSM medium with DLN as a sole carbon source. In addition, strain P10 can use commercial PUR foam as the sole carbon source for growth. Brevibacillus sp. P10 can degrade 50 mg PUR foam after 6 days growth in MSM medium supplemented with 5% (V/V) LB after optimization of degradation conditions. This indicates that Brevibacillus sp. P10 has potential to be used in biodegradation of PUR waste.

Microbial degradation of polyurethane plastics / 生物工程学报

Plastic pollution has become a global environmental issue, making it necessary to explore the environmental disposal technology for plastic waste. Recently, we and other researchers have individually found microorganisms or enzymes from nature that can degrade synthetic plastic. These findings indicated that the capability of these microorganisms or enzymes to degrade plastic could be used for the disposal of plastic waste. Polyurethane (PUR) was one of the most used general plastic and its plastic waste occupied 30% of the total volume of different plastic waste. This review tried to provide a comprehensive summary of the researches on microbial degradation of PUR plastic in the past 70 years since its invention, and focused on the PUR-degrading fungi, bacteria, genes or enzymes, degradation products and the corresponding biological disposal technologies. We finally proposed the key scientific challenges on the development of high efficient biological disposal for PUR waste in the perspective researches.

Diversity and effectiveness of tropical mangrove soil microflora on the degradation of polythene carry bags

The diversity and load of heterotrophic bacteria and fungi associated with the mangrove soil from Suva, Fiji Islands, was determined by using the plate count method. The ability of the bacterial isolates to produce various hydrolytic enzymes such as amylase, gelatinase and lipase were determined using the plate assay. The heterotrophic bacterial load was considerably higher than the fungal load. There was a predominance of the gram positive genus, Bacillus. Other genera encountered included Staphylococcus, Micrococcus, Listeria and Vibrio. Their effectiveness on the degradation of commercial polythene carry bags made of high density polyethylene (HDPE) and low density polyethylene (LDPE) was studied over a period of eight weeks in the laboratory. Biodegradation was measured in terms of mean weight loss, which was nearly 5 % after a period of eight weeks. There was a significant increase in the bacterial load of the soil attached to class 2 (HDPE) polythene. After eight weeks of submergence in mangrove soil, soil attached to class 1 and class 3 polythene mostly had Bacillus (Staphylococcus predominated in class 2 polythene). While most of the isolates were capable of producing hydrolytic enzymes such as amylase and gelatinase, lipolytic activity was low. Class 2 HDPE suffered the greatest biodegradation. Rev. Biol. Trop. 55 (3-4): 777-786. Epub 2007 December, 28.

Se determinó la diversidad y la carga de bacterias heterotróficas, así como los hongos asociados al suelo del manglar de Suva, Islas Fiji, utilizando el método de conteo de placas, usado también para medir la capacidad de bacterias aisladas para producir enzimas hidrolíticas como amilasa, gelatinasa y lipasa. La carga bacteriana heterotrófica resultó ser considerablemente más alta que la carga funguicida. Hubo predominancia de bacterias "Gram-positivas" del género de Bacillus. Otros géneros encontrados fueron Staphylococcus, Micrococcus, Listeria y Vibrio. La eficacia de esta microflora en la degradación del polietileno comercial de bolsas hechas de polietileno de alta densidad (HDPE) y de baja densidad (LDPE) fue estudiada en el laboratorio por un periodo de ocho semanas. La biodegradación fue medida en términos de pérdida de peso, la cual indicó una disminución del 5 %. Después de ocho semanas en el suelo de un manglar, el polietileno clase 1 y clase 3 contenía fundamentalmente Bacillus, pero en el polietileno clase 2 predominó el género Staphylococcus. Mientras que la mayoría de bacterias aisladas fueron capaces de producir enzimas hidrolíticas como la amilasa y la gelatinasa, la actividad lipolítica fue muy baja. La clase 2 (HDPE) experimentó la mayor biodegradación.