Freshwater alga Raphidocelis subcapitata undergoes metabolomic changes in response to electrostatic adhesion by micrometer-sized nylon 6 particles

Satomi Mizukami-Murata,Kensuke Sakurai,Yuji Suzuki,Hiromasa Yamashita

doi:10.1007/s11356-021-15300-8

Satomi Mizukami-Murata, Kensuke Sakurai + Show 2 more

Open Access

https://doi.org/10.1007/s11356-021-15300-8

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Abstract

Nylon powders are a type of microplastic (MP) used in personal care products such as cosmetics and sunscreens. To determine the effects of nylon polymers on freshwater microalgae, we investigated the effects of two types of micrometer-sized nylon polymers, i.e., powdered nylon 6 (Ny6-P) and nylon 12 (Ny12), and four other micrometer-sized MPs, i.e., low-density polyethylene, polyethylene terephthalate, polystyrene, and ultra-high-molecular-weight polyethylene, on the microalga Raphidocelis subcapitata. The results showed that Ny6-P inhibited R. subcapitata growth more than the other MPs; R. subcapitata growth was inhibited by 54.2% with 6.25 mg/L Ny6-P compared with the control. Ny6-P in the culture media adhered to R. subcapitata cells electrostatically, which may have disrupted growth and photosynthetic activity. Metabolomic analysis revealed that many metabolites related to the amino acid catabolic pathway and γ-glutamyl cycle were induced, which might trigger responses to avoid starvation and oxidative stress. Our study provides important information on the effects of Ny6-P on algae in freshwater environments.

Highlights

Since the 1950s, the production and use of plastics has increased globally, which has affected the environment, especially in terms of increased amounts of microplastics (MPs) released into aquatic environments (Monteleone et al 2019)
Our results suggest that oxidative stress, not observed directly, was produced in R. subcapitata cells adsorbed by nylon 6 (Ny6)-P, and that the cells responded via the activation of antioxidant systems such as the γ-glutamyl cycle
The effects of micrometer-sized nylon polyamides (Ny6 and nylon 12 (Ny12)) on R. subcapitata were investigated through comparison with other micrometer-sized MPs (i.e., low-density PE (LDPE), PE terephthalate (PET), PS, and UHPE)

Summary

Introduction

Since the 1950s, the production and use of plastics has increased globally, which has affected the environment, especially in terms of increased amounts of microplastics (MPs) released into aquatic environments (Monteleone et al 2019). Innovative Materials and Resources Research Center, Public Works Research Institute, Minamihara, 1-6, Tsukuba, Ibaraki 305-8516, Japan aquatic environments mainly via domestic wastewater (Thompson et al 2004; Mintenig et al 2017). The use of plastics has resulted in MP contamination in aquatic environments and is drawing attention worldwide. In addition to their presence in marine environments, MPs have been detected at concentrations ranging from 0.00297 to 2.58 g/L in freshwater environments, including rivers, lakes, and wastewater treatment plants, in North America, Asia, Europe, and Australia (Eerkes-Medrano et al 2015; Rezania et al 2018; Li et al 2019). Various types of MP polymers, such as polyamide (PA), polyethylene (PE), PE terephthalate (PET), polypropylene (PP), and polystyrene (PS), have been detected in these regions (Li et al 2019; Rezania et al 2018)

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