College of Resources and Environment, Henan Agricultural University, Zhengzhou 450002, China.
School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China.
Sci Total Environ. 2024 Jun 1;927:171966. doi: 10.1016/j.scitotenv.2024.171966. Epub 2024 Mar 25.
Benzo(a)pyrene (BaP) is posing serious threats to soil ecosystems and its bioremediation usually limited by environmental factors and microbial activity. Humic acid (HA), a ubiquitous heterogeneous organic matter, which could affect the fate of environmental pollutants. However, the impact of HA on bioremediation of organic contamination remains controversial. In the present study, the biodegradation of BaP by Paracoccus aminovorans HPD-2 with and without HA was explored. Approximately 87.4 % of BaP was biodegraded in the HPD-2 treatment after 5 days of incubation, whereas the addition of HA dramatically reduced BaP biodegradation to 56.0 %. The limited BaP biodegradation in the HA + HPD-2 treatment was probably due to the decrease of BaP bioavailability which induced by the adsorption of HA with unspecific interactions. The excitation-emission matrix (EEM) of fluorescence characteristics showed that strain HPD-2 was responsible for the presence of protein-like substances and the microbial original humic substances in the HPD-2 treatment. Addition of HA would result in the increase of soluble microbial humic-like material, which should ascribe to the biodegradation of BaP and probably utilization of HA. Furthermore, both the growth and survival of strain HPD-2 were inhibited in the HA + HPD-2 treatment, because of the limited available carbon source (i.e. BaP) at the presence of HA. The expression of gene1789 and gene2589 dramatically decreased in the HA + HPD-2 treatment, and this should be responsible for the decrease of BaP biodegradation as well. This study reveals the mechanism that HA affect the BaP biodegradation, and the decrease of biodegradation should ascribe to the interaction of HA and bacterial strain. Thus, the bioremediation strategies of PAHs need to consider the effects of organic matter in environment.
苯并(a)芘（BaP）对土壤生态系统构成严重威胁，其生物修复通常受到环境因素和微生物活性的限制。腐殖酸（HA）是一种普遍存在的异质有机物质，它会影响环境污染物的归宿。然而，HA 对有机污染生物修复的影响仍存在争议。本研究探讨了腐殖酸存在与否时，假单胞菌 HPD-2 对 BaP 的生物降解作用。在 5 天的孵育后，HPD-2 处理中约有 87.4%的 BaP 被生物降解，而添加 HA 则将 BaP 的生物降解率显著降低至 56.0%。在 HA+HPD-2 处理中，BaP 生物降解有限可能是由于 HA 通过非特异性相互作用吸附导致 BaP 生物可利用性降低所致。荧光特性激发-发射矩阵（EEM）表明，HPD-2 菌株负责存在于 HPD-2 处理中的蛋白质样物质和微生物原始腐殖质。添加 HA 会导致可溶微生物腐殖质样物质的增加，这归因于 BaP 的生物降解，可能还与 HA 的利用有关。此外，由于 HA 的存在限制了可利用的碳源（即 BaP），HA+HPD-2 处理中的菌株 HPD-2 的生长和存活均受到抑制。HA+HPD-2 处理中基因 1789 和基因 2589 的表达明显下降，这也应该是 BaP 生物降解下降的原因。本研究揭示了 HA 影响 BaP 生物降解的机制，生物降解的降低归因于 HA 和细菌菌株的相互作用。因此，多环芳烃的生物修复策略需要考虑环境中有机物的影响。
