Perna canaliculus as an Ecological Material in the Removal of o-Cresol Pollutants from Soil

Soil contamination with cresol is a problem of the 21st century and poses a threat to soil microorganisms, humans, animals, and plants. The lack of precise data on the potential toxicity of o-cresol in soil microbiome and biochemical activity, as well as the search for effective remediation methods, inspired the aim of this study. Soil is subjected to four levels of contamination with o-cresol: 0, 0.1, 1, 10, and 50 mg o-cresol kg−1 dry matter (DM) of soil and the following are determined: the count of eight groups of microorganisms, colony development index (CD) and ecophysiological diversity index (EP) for organotrophic bacteria, actinobacteria and fungi, and the bacterial genetic diversity. Moreover, the responses of seven soil enzymes are investigated. Perna canaliculus is a recognized biosorbent of organic pollutants. Therefore, microbial biostimulation with Perna canaliculus shells is used to eliminate the negative effect of the phenolic compound on the soil microbiome. Fungi appears to be the microorganisms most sensitive to o-cresol, while Pseudomonas sp. is the least sensitive. In o-cresol-contaminated soils, the microbiome is represented mainly by the bacteria of the Proteobacteria and Firmicutes phyla. Acid phosphatase, alkaline phosphatase and urease can be regarded as sensitive indicators of soil disturbance. Perna canaliculus shells prove to be an effective biostimulator of soil under pressure with o-cresol.

Energetic Value of Elymus elongatus L. and Zea mays L. Grown on Soil Polluted with Ni2+, Co2+, Cd2+, and Sensitivity of Rhizospheric Bacteria to Heavy Metals

Plants, and microorganisms associated with them, offer an effective tool for removing pollutants, such as heavy metals, from the soil environment. The aim of this study was to determine changes caused by Ni2+, Co2+, and Cd2+ in the genetic diversity of soil-populating bacteria and the effect these heavy metals on the heating value of elongated coach grass (Elymus elongatus L.) and maize (Zea mays L.). Microorganisms support plants in removing heavy metals from soil. These plants can then be used for energetic purposes. The study aim was accomplished by determining counts of microorganisms and their resistance (RS) to Ni2+, Co2+, Cd2+, their colony development index (CD), ecophysiological diversity index (EP), and diversity established with the next generation sequencing (NGS) method. Further analyses aimed to establish test plants resistance to pollution with heavy metals and their heating value. Organotrophic bacteria turned out to be the most resistant to Co2+, whereas actinobacteria—to Cd2+ effects. At all taxonomic levels, the genetic diversity of bacteria was most adversely influenced by Cd2+ in the soil sown with Zea mays L. Bacteria belonging to Arthrobacter, Rhodoplanes, Kaistobacter, Devosia, Phycicoccus, and Thermomonas genera showed high tolerance to soil pollution with Ni2+, Co2+, and Cd2+, hence they should be perceived as potential sources of microorganisms useful for bioaugmentation of soils polluted with these heavy metals. Ni2+, Co2+, and Cd2+ had no effect on the heating value of Elymus elongatus L. and Zea mays L. The heating value of 1 kg of air-dry biomass of the tested plants was relatively high and ranged from 14.6 to 15.1 MJ. Elymus elongatus L. proved more useful in phytoremediation than Zea mays L.

Bioindication of soil of unauthorized landfills in the Carpathian region

The article presents the results of monitoring the area adjacent to the Carpathian Biosphere Reserve for the detection of unauthorized landfills and examines the ecological status of these soils. Four unauthorized landfills of solid waste in Pidhirna, Stanislav, Steryshora, and Feresok tracts with an area of 0.15 to 1.5 ha with a waste accumulation period of 12–22 years and different morphological composition which had a significant impact on the ecological status of the soil have been identified. Bioindication methods have shown changes in the soil microbial cenoses under the direct influence of unauthorized landfills of solid waste, namely increased the number of organotrophic bacteria and micromycetes and decreased number of nitrogen-fixing microorganisms. The highest number of bacteria using nitrogen of organic compounds (25.36–28.61 million CFU/g soil) and micromycetes (51.8–76.8 thousand CFU/g soil) was fixed in the soils in the tract PidhirnaandFeresok with advantage of 1.5–1.7 times and 2.5–3.8 times compared to the soil of the protected area. Increasing the number of pedotrophic and oligotrophic microorganisms and microorganisms that assimilate organic forms of nitrogen, on average, 2.70, 2.84 and 1.48 times has been affected the direction of the main soil-microbiological processes. The coefficient of oligotrophicity varied in the range of 0.21–0.30, mineralization-immobilization one — 1.22–1.38, pedotrophic one — 0.55–0.96 with a maximum in the soil of the landfill in the tracts of Feresok and Pidhirna, which indicates the strengthening of microbiological processes of mineralization and decomposition of soil organic matter, including humus compounds. A close relationship was established between the duration of solid waste storage in a certain area and the level of soil phytotoxicity (r = 0.92). In the soil of landfills in Pidhirna, Steryshora and Feresok tracts, the phytotoxicity index is significant (over 50%), which indicates a high level of soil ecosystem pollution and increased environmental risks in the area of unauthorized accumulation of solid waste.

Microbiological and Biochemical Properties in Eutric/Dystric Brunic Arenosols, Eutric/Endocalcaric Cambisols, and Haplic/Albic Luvisols Soils

To understand the role of microorganisms in the functioning of forest ecosystems, the structure of bacterial communities and the enzymatic activity were determined in forest soils representing the following soil subtypes: Eutric/Dystric Brunic Arenosols (A), Eutric/Endocalcaric Cambisols (C), and Haplic/Albic Luvisols (L). Their microbiological and biochemical properties were compared based on bacterial counts and diversity, and activities of seven soil enzymes: dehydrogenases, catalase, urease, acid phosphatase, alkaline phosphatase, arylsulfatase, and β-glucosidase. Organotrophic bacteria and actinobacteria were the most abundant and featured the highest values of the EP (ecophysiological diversity index) in the Haplic/Albic Luvisol soil. In turn, the CD (colony development index) values of these bacterial groups were the highest in the Eutric/Endocalcaric Cambisols. The OTU number of bacteria allowed concluding that, at the class level, the Eutric/Dystric Brunic Arenosols and Haplic/Albic Luvisols were predominated by Alphaproteobacteria belonging to Proteobacteria, whereas the Eutric/Endocalcaric Cambisols by Actinobacteria. At the family rank, the Eutric/Dystric Brunic Arenosols were colonized in the highest numbers by Mycobacteriaceae, Rhodospirillaceae, Koribacteriaceae, and Acidobacteriaceae; the Eutric/Endocalcaric Cambisols by Nocardiaceae, Bradyrhizobiaceae, and Mycobacteriaceae, whereas Haplic/Albic Luvisols by Sinobacteriaceae and Rhodospirillaceae. Four bacterial genera, i.e., Rhodoplanes, Burkholderia belonging to Proteobacteria, Mycobacterium belonging to Actinobacteria, and Candidatus Solibacter belonging to Acidobacteria, were identified in all soils tested. The genetic diversity of bacteria was proved the highest in Eutric/Endocalcaric Cambisols. In turn, the highest enzymatic activity was found for Haplic/Albic Luvisols, while the lowest one for Eutric/Endocalcaric Cambisols. The present study results point out to significant differences between the soil types analyzed in terms of the diversity and structure of their bacterial communities and their enzymatic properties.

Effect of Bentonite and Barley Straw on the Restoration of the Biological Quality of Agriculture Soil Contaminated with the Herbicide Successor T 550 SE

Environmentally safe ways are sought to prevent the accumulation and to accelerate the degradation of herbicide active substances in agricultural soil. This study aimed to determine the effectiveness of finely-ground barley straw and bentonite in mitigating the effects of agricultural soil contamination with Successor T 550 SE. This herbicide was applied in the following doses: 0, 0.73, and 14.63 mg of the active substance per kg. The bentonite and spring barley straw were used at 10 g/kg. The action of these additives was compared to soil without the addition of straw and bentonite. The application of the experimental herbicide disturbed microbial systems, such as organotrophic bacteria, oligotrophic bacteria and their spores, actinobacteria, and fungi. A positive response to the herbicide dose of 14.63 mg a.s./kg was observed only for spores of oligotrophic bacteria. Further disturbances were observed in the agricultural soil biochemical properties, i.e., in the activity of dehydrogenases, urease, catalase, acid, and alkaline phosphatase, arylsulfatase, and β-glucosidase. A significant decrease in the activity of dehydrogenases, acid phosphatase, and arylsulfatase was observed following the application of 14.63 mg a.s./kg. The yield of maize decreased following the application of the analysed plant protection agent. Based on the soil quality index (BA), the addition of straw was more effective in restoring soil homeostasis than bentonite. Both bentonite and straw can be successfully used to improve agricultural soil biological activity. However, more effective mitigation of the negative effects of the herbicide in soil was observed in objects supplemented with barley straw. This improved the microbiological and biochemical properties of the soil. Barley straw was more effective than bentonite in restoring soil biological balance.

Insight into the hidden bacterial diversity of Lake Balaton, Hungary

In the present study, the prokaryotic community structure of the water of Lake Balaton was investigated at the littoral region of three different points (Tihany, Balatonmáriafürdő and Keszthely) by cultivation independent methods [next-generation sequencing (NGS), specific PCRs and microscopy cell counting] to check the hidden microbial diversity of the lake. The taxon-specific PCRs did not show pathogenic bacteria but at Keszthely and Máriafürdő sites extended spectrum beta-lactamase-producing microorganisms could be detected. The bacterial as well as archaeal diversity of the water was high even when many taxa are still uncultivable. Based on NGS, the bacterial communities were dominated by Proteobacteria, Bacteroidetes and Actinobacteria, while the most frequent Archaea belonged to Woesearchaeia (Nanoarchaeota). The ratio of the detected taxa differed among the samples. Three different types of phototrophic groups appeared: Cyanobacteria (oxygenic phototrophic organisms), Chloroflexi (anaerobic, organotrophic bacteria) and the aerobic, anoxic photoheterotrophic group (AAPs). Members of Firmicutes appeared only with low abundance, and Enterobacteriales (order within Proteobacteria) were present also only in low numbers in all samples.