Search

The wide distribution of p-hydroxybenzoic acid (PHBA) in the environments has attracted great concerns due to its potential risks to organisms. Bioremediation is considered a green way to remove PHBA from environment. Here, a new PHBA-degrading bacterium Herbaspirillum aquaticum KLS-1was isolated and its PHBA degradation mechanisms were fully evaluated. Results showed that strain KLS-1 could utilize PHBA as the sole carbon source and completely degrade 500 mg/L PHBA within 18 h. The optimal conditions for bacterial growth and PHBA degradation were pH values of 6.0-8.0, temperatures of 30 °C-35 °C, shaking speed of 180 rpm, Mg 2+ concentration of 2.0 mM and Fe 2+ concentration of 1.0 mM. Draft genome sequencing and functional gene annotations identified three operons (i.e., pobRA, pcaRHGBD and pcaRIJ) and several free genes possibly participating in PHBA degradation. The key genes pobA, ubiA, fadA, ligK and ubiG involved in the regulation of protocatechuate and ubiquinone (UQ) metabolisms were successfully amplified in strain KLS-1 at mRNA level. Our data suggested that PHBA could be degraded by strain KLS-1 via the protocatechuate ortho-/meta-cleavage pathway and UQ biosynthesis pathway. This study has provided a new PHBA-degrading bacterium for potential bioremediation of PHBA pollution., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Selenium (Se) is essential for the basic functions of life, but the low daily intake of Se urges us to find reliable ways to increase food Se content. Plant-growth-promoting bacteria (PGPB) have shown potential in enhancing plant growth and Se accumulation. In this study, the soils collected from a Se tailing were used to isolate Se-tolerant PGPB. The results showed that a total of three strains were identified. Strain LWS1, belonging to Priestia sp., grew well in M9 medium and exhibited typical PGP characteristics by an IAA-production ability of 24.3 ± 1.37 mg·L−1, siderophore-production ability of 0.23 ± 0.04 and phosphate-solubilizing ability of 87.5 ± 0.21 mg·L−1. Moreover, LWS1 strain tolerated selenite (SeIV) up to 90 mM by a LC50 of 270.4 mg·L–1. Further investigations demonstrated that the inoculation of strain LWS1 resulted in up to 19% higher biomass and 75% higher Se concentration in rice (Oryza sativa L.) than uninoculated treatments. Our study has provided evidence that microbial Se biofortification through inoculating with Priestia sp. strain LWS1 is an alternative way to improve Se uptake in crops and maintain human health. [ABSTRACT FROM AUTHOR]