Earthworms and rice straw enhanced soil bacterial diversity and promoted the degradation of phenanthrene

Abstract

Background Since the industrial revolution, the contamination of agricultural soils by polycyclic aromatic hydrocarbons (PAHs) has increasingly become of serious global environmental concern and poses a huge threat to human beings and natural ecosystems. Microbial degradation is a proved technology mostly used to depollute polycyclic aromatic hydrocarbon (PAH) in the environment. However, very limited information is available regarding the interaction of earthworms with rice straw on the soil microbial community and the degradation of phenanthrene. This study was performed to enlighten the rice straw and earthworms’ interaction on soil bacterial abundance and structure and phenanthrene removal. Results Result about functional gene information revealed that both rice straw and earthworm enhanced phenanthrene degradation. Subsequently, both Shannon diversity index (r2 = − 0.8807, p < 0.001) and bacterial 16S rRNA genes (r2 = − 0.7795, p < 0.001) negatively correlated with the remaining phenanthrene concentration in soil. The application of both rice straw and earthworms in soil had the lowest ratio of soil remaining phenanthrene concentration (0.16 ± 0.02), the highest Shannon diversity index (6.45 ± 0.2) and the highest bacterial 16S rRNA genes. This implied that both earthworms and rice straw might improve the phenanthrene metabolism by increasing soil bacteria diversity. The abundance of genera Pseudomonas, Luteimonas, Rhodanobacter, Sphingomonas, Gemmatimonas, Flavobacterium, and Leifsonia was significantly increased in the presence of both earthworms and rice straw and was found to negatively correlate with the remaining phenanthrene concentration in soil. Conclusion Based on these results, this study offers clear and strong evidences that the positive interaction between earthworms and rice straw could promote phenanthrene degradation in soil. These finding will improve our understanding on the importance of the natural resources forsaken and how they can interact with the soil macro- and microorganisms to change soil structure and enhance PAH degradation in soil.

Effects of straw returning combined with earthworm addition on nitrification and ammonia oxidizers in paddy soil

“…In the present study, SRW treatment increased the AOA community diversity, while W and SR did not, since earthworms can promote straw decomposition (Elyamine and Hu, 2020). A great quantity of organic N was increased in the soil through straw returning, while available N was released by the feeding and casting activities of earthworms (Edwards and Arancon, 2022).…”

Evaluating earthworms as candidates for remediating pesticide contaminated agricultural soil: A review

“…Earthworms prevented the creation of the bound fraction while also promoting the release and mineralisation of bound residues (Hickman & Reid, 2008). Elyamine and Hu (2020) demonstrated the favourable interaction between earthworms, Eisenia fetida and Aporrectodea caliginosa and rice straw in soil. Their interaction with soil microbes helped to promote phenanthrene breakdown in the soil.…”

Analysis of Factors Influencing Plant–Microbe Combined Remediation of Soil Contaminated by Polycyclic Aromatic Hydrocarbons

“…Microbial activity has become one of the most important mechanisms for the remediation of PAHs-contaminated soil because microorganisms are ubiquitous in the environment. When studying the mechanism of PAHs biodegradation, scientists mostly focus on naphthalene and phenanthrene with fewer than four rings [135][136][137]. Although PAHs can be mineralized under both aerobic and anaerobic conditions, aerobic degradation is significantly superior to anaerobic degradation in terms of degradation rate [138].…”