Diversity of organotrophic bacteria, activity of dehydrogenases and urease as well as seed germination and root growth Lepidium sativum, Sorghum saccharatum and Sinapis alba under the influence of polycyclic aromatic hydrocarbons

Abstract

Polycyclic aromatic hydrocarbons are organic compounds with highly toxic, carcinogenic, and mutagenic properties, which adversely affect the basic biological parameters of the soil, including the count of microorganisms, and the enzymatic activity. In addition to disturbances to the biological activity of the soil, PAHs may also exhibit toxic effects on plants. In view of the above, the study involved testing aimed at the determination of the effects of polycyclic aromatic hydrocarbons in a form of naphthalene, phenanthrene, anthracene and pyrene on the count, colony development (CD) index, ecophysiological (EP) diversity index of organotrophic bacteria, and the activity of soil dehydrogenases and soil urease. Moreover, an attempt was made to determine the soil’s resistance based on the activity of the above-listed enzymes, and the effect of polycyclic aromatic hydrocarbons on seed germination and root growth was assessed by Lepidium sativum, Sorghum saccharatum, and Sinapis alba. In addition, the species of bacteria found in a soil subjected to strong pressure of polycyclic aromatic hydrocarbons were isolated. The experiment was performed in a laboratory on samples of loamy sand. Polycyclic aromatic hydrocarbons were introduced into the soil in an amount of 0, 1000, 2000, and 4000 mg kg−1 of soil dry matter. Germination and growth of cress (L. sativum), white mustard (S. alba), and sweet sorghum (S. saccharatum) were determined using Phytotoxkit tests. It was found that the tested PAHs increased the average colony counts of organotrophic soil bacteria; pyrene did so to the greatest extent (2.2-fold relative to non-contaminated soil), phenanthrene to the smallest extent (1.4-fold relative to non-contaminated soil). None of the PAHs changed the value of the bacterial colony development (CD) index, while anthracene and pyrene increased the value of the eco-physiological (EP) diversity indicator. PAHs lowered the activity of the tested enzymes. The activity of dehydrogenases was dependent on a greater extent by the type of hydrocarbon (54.56 %) rather than by the dose (10.64 %), while for the activity of urease, it was the opposite. The greater extent was dependent on dose (95.42 %) rather than by type (0.21 %). Dehydrogenases are characterised by greater resistance to the action of PAHs than urease. Based on seed germination and root growth, it has shown that S. alba is best suited, being the most vulnerable plant, while S. saccharatum is the least suited. Subjecting a soil to strong pressure of PAHs leads to disturbances to the biological parameters of the soil, seed germination, and root growth L. sativum, S. saccharatum, and S. alba.

Halo-tolerant plant growth promoting rhizobacteria for improving productivity and remediation of saline soils

“…Improvement of C cycling in saline soil is reported when inoculated with PGPR [147] . Another mechanism of action reported by Lipińska et al [148] highlights that bacterial inoculation increases the dehydrogenase activity which is suggested to be directly correlated with soil microbial biomass. Islam et al [149] described increase in microbial biomass carbon and dehydrogenase activity in saline soil upon inoculation with HT-PGPR B. cereus Pb25.…”

The role of artificial root exudate components in facilitating the degradation of pyrene in soil

“…The activities of three soil enzymes, i.e., urease, catalase and dehydrogenase, were determined. The activity of urease was measured using the method described in a previous study 54 . Briefly, a 10% aqueous solution of urea was added to soil as substrate for urease.…”

“…Then, the indicator reagent, which included a specific concentration of peroxidase, was added to the soil filtrate, which was left to stand for 5 min before measuring its absorbance at 505 nm. The dehydrogenase activity was assayed by measuring the absorbance at 485 nm following the addition of triphenyltetrazolium chloride (TTC) as the substrate, which was converted to triphenylformazan (TPF) 54 .…”

Microbiological and Biochemical Activity in Soil Contaminated with Pyrene Subjected to Bioaugmentation

“…7 Enzymatic activity in soil contaminated with pyrene presented by PCA method regardless of the type of consortium (a) and the dose of pyrene (b); Deh, dehydrogenases; Cat, catalase; Ure, urease; Pac, acid phosphatase; Pal, alkaline phosphatase; Aryl, arylsulphatase; Glu, β-glucosidase; P, pyrene; 0, 100, 1000-doses of pyrene (mg kg −1 DM soil); 2, 8-research terms (in weeks); C, P1, P2-C-control (with pyrene, without consortia); P1, bacterial consortium (pyrene + Bacillus frigoritolerans Z2B-19, Bacillus simplex 2-134, Bacillus thuringiensis ex4); P2, bacterial consortium (pyrene + Bacillus pumilus Bp-11, Bacillus safensis L22, Bacillus aerophilus KUDC1741); Fuchsia Greek capital letter delta; blue Latin small letter "O" end of vectors; cases and fungi in the 8th week of the study probably resulted from the degradation of organic substances by those microorganisms, which gradually released carbon from pyrene. The microorganisms can use xenobiotics as an additional source of carbon and energy by adapting to the new environmental conditions and boosting own metabolic processes (Zafra et al 2014;Lipińska et al 2015;.…”