Co-occurrence Interaction Networks of Extremophile Species Living in a Copper Mining Tailing

Copper mining tailings are characterized by high concentrations of heavy metals and an acidic pH, conditions that require an extreme adaptation for any organism. Currently, several bacterial species have been isolated and characterized from mining environments; however, very little is known about the structure of microbial communities and how their members interact with each other under the extreme conditions where they live. This work generates a co-occurrence network, representing the bacterial soil community from the Cauquenes copper tailing, which is the largest copper waste deposit worldwide. A representative sampling of six zones from the Cauquenes tailing was carried out to determine pH, heavy metal concentration, total DNA extraction, and subsequent assignment of Operational Taxonomic Units (OTUs). According to the elemental concentrations and pH, the six zones could be grouped into two sectors: (1) the “new tailing,” characterized by neutral pH and low concentration of elements, and (2) the “old tailing,” having extremely low pH (~3.5) and a high concentration of heavy metals (mainly copper). Even though the abundance and diversity of species were low in both sectors, the Pseudomonadaceae and Flavobacteriaceae families were over-represented. Additionally, the OTU identifications allowed us to identify a series of bacterial species with diverse biotechnological potentials, such as copper bioleaching and drought stress alleviation in plants. Using the OTU information as a template, we generated co-occurrence networks for the old and new tailings. The resulting models revealed a rearrangement between the interactions of members living in the old and new tailings, and highlighted conserved bacterial drivers as key nodes, with positive interactions in the network of the old tailings, compared to the new tailings. These results provide insights into the structure of the soil bacterial communities growing under extreme environmental conditions in mines.

Change of Ba concentration by species and organ in several fruits grown in city centers

Heavy metals are elements that are very harmful to human and environmental health. Heavy metal concentration in the fruits grown in city centers can reach very high levels and consuming these fruits as food causes a direct intake of heavy metals, which these fruits contain, into a human body and can pose a significant health risk. All the compounds of barium (Ba), which is one of the most dangerous heavy metals, are toxic. Thus, determining the Ba concentration in plants, which are grown in areas with high pollution and consumed as food, is very important. In the present study, it was aimed to determine the change of Ba concentration by species and organ in several fruits grown in areas with high traffic density. Within the scope of this study, Ba concentrations in leaf, branch, bark, seed, and fruits of Prunus ceresifera, Tilia tomentosa, Prunus avium, and Prunus cerasus were compared. As a result, it was determined that the change of Ba concentrations by species and the change by organ were statistically significant in all organs and in all species, respectively. In general, the lowest values were found in Prunus cerasus or Prunus avium, whereas the highest values were observed in Tilia tomentosa. Considering the organs, the lowest values were found in seed and the highest ones in bark and branch.

Heavy Metal Contamination of Natural Foods Is a Serious Health Issue: A Review

Heavy metals play an important role in the homeostasis of living cells. However, these elements induce several adverse environmental effects and toxicities, and therefore seriously affect living cells and organisms. In recent years, some heavy metal pollutants have been reported to cause harmful effects on crop quality, and thus affect both food security and human health. For example, chromium, cadmium, copper, lead, and mercury were detected in natural foods. Evidence suggests that these elements are environmental contaminants in natural foods. Consequently, this review highlights the risks of heavy metal contamination of the soil and food crops, and their impact on human health. The data were retrieved from different databases such as Science Direct, PubMed, Google scholar, and the Directory of Open Access Journals. Results show that vegetable and fruit crops grown in polluted soil accumulate higher levels of heavy metals than crops grown in unpolluted soil. Moreover, heavy metals in water, air, and soil can reduce the benefits of eating fruits and vegetables. A healthy diet requires a rational consumption of foods. Physical, chemical, and biological processes have been developed to reduce heavy metal concentration and bioavailability to reduce heavy metal aggregation in the ecosystem. However, mechanisms by which these heavy metals exhibit their action on human health are not well elucidated. In addition, the positive and negative effects of heavy metals are not very well established, suggesting the need for further investigation.

Increased sensitivity of heavy metal bioreporters in transporter deficient Synechocystis PCC6803 mutants

The detection and identification of heavy metal contaminants are becoming increasingly important as environmental pollution causes an ever-increasing health hazard in the last decades. Bacterial heavy metal reporters, which constitute an environmentally friendly and cheap approach, offer great help in this process. Although their application has great potential in the detection of heavy metal contamination, their sensitivity still needs to be improved. In this study, we describe a simple molecular biology approach to improve the sensitivity of bacterial heavy metal biosensors. The constructs are luxAB marker genes regulated by the promoters of heavy metal exporter genes. We constructed a mutant strain lacking the cluster of genes responsible for heavy metal transport and hence achieved increased intracellular heavy metal content of the Synechocystis PCC6803 cyanobacterium. Taking advantage of this increased intracellular heavy metal concentration the Ni2+; Co2+ and Zn2+ detection limits of the constructs were three to tenfold decreased compared to the sensitivity of the same constructs in the wild-type cyanobacterium.

The health risk assessment of heavy metal concentration in drinking water samples from selected location of Kauru Local Government Area Kaduna State Nigeria

No Abstract.

The genetic diversity of Asplenium viride (Aspleniaceae) fern colonizing heavy metal-polluted sites

Heavy metals can affect the morphology, physiology and evolution of plants. Asplenium viride is a diploid species, belonging to the largest genus of the cosmopolitan fern family Aspleniaceae, and occurring on various types of alkaline rocks. It is known to colonize sites with high concentrations of heavy metals, exhibiting changes in frond morphology. Microevolutionary processes, manifesting as changes in genome size and new genotype formation, can ultimately lead to the formation of new subspecies and speciation. This study aimed to evaluate the morphological and genetic diversity of A. viride, and to test for a potential correlation between variability and heavy metal concentration. Analysis of A. viride specimens, from one metalliferous site and five non-metalliferous localities, showed no apparent variation in genome size between plants from affected and non-affected sites. There was no significant correlation between genetic variability and heavy metal concentration. This was possibly due to intragametophytic selfing, caused by patchy habitats and subsequent founder effects, resulting from long-distance colonization by single spores.

The Heavy Metal Characteristics (Pb and Cu) in Wideng Crab Tissue from the Gonjol River, Demak

Objective and Background: The Gonjol river serves as a lifeline for the communities surrounding Demak's brackish water ponds. Currently, factory waste is poisoning rivers. The purpose of this research was to investigate the levels of heavy metals Pb and Cu in Wideng crab tissue, water, and sediment in the Gonjol river's upper course and estuary. Methods: This study was place from January to March 2020. Heavy metal concentration was determined using atomic absorption spectroscopy. The linear regression method was used to analyze the data. Results: Except for Cu in upstream and estuary sediments, the concentration of Pb and Cu in the waters, sediments, and Wideng crab tissue remained below the acceptable limits. Heavy metals Pb and Cu in both sediment and tissue did not reveal a significant association in the upstream and estuary, although there was a correlation between water and tissue. There is no association between silt and water in the upstream and estuary. The river's quality is based on the Decree of the Minister of the Environment of the Republic of Indonesia No.115 of 2003, which places it in category C, which means it has moderate levels of Pb and Cu pollution. While tissue and sediment levels are below the tolerance limit. Conclusion: The state of the Gonjol River is a source of concern, particularly the circumstances of Cu and Pb, which allow bioaccumulation in the future, posing a threat to the ecosystem and the communities surrounding it.

Determination of Heavy Metal Concentration in Two Bony Fish (Catfish and Tilapia) from Orashi River in Rivers State, Nigeria

The research was intended to study the influence of human and industrial activities on the Orashi River and two bony fish (Clarias gariepinus and Tilapia nilotica). Three groups are observed to have impacted the environment – Oil/gas industries, tyre burning from abattoir, untreated human and animal waste from settlers and the abattoir. The study was carried out from September 2019 to August 2020. The mean concentrations of the parameters studied in some samples were close to or exceeded World Health Organization (WHO) and Federal Ministry of Environment (FMEnv) recommended limits for drinking water and seafood. The results from this study have provided information on the heavy metals profile on the fish of the river. The level of heavy metals in the muscle of Catfish and Tilapia showed a range of Cadmium in Catfish (1-3.9mg/kg and Tilapia (0.1-4.2mg/kg) with the highest level occurring in station 2 (3.47mg/kg for Catfish and 3.39mg/kg for Tilapia) which is high with regard to FAO 19835, FAO/WHO 10896, EEC 20054 permissible limit of 0.01mg/l and USEPA SQG (1mg/kg) level in seafood. The levels of essential heavy metals in fish muscle were Copper (Catfish-10.9-33mg/kg, Tilapia -17.3-40.6mg/kg), Iron (Catfish-1.0-2.5mg/kg, Tilapia -0.1-5.6mg/kg) were within the FAO 1983 permissible limit while Zinc (Catfish-22-213.2mg/kg) and Tilapia (30.1-196mg/kg) exceeds the limit in some stations. Catfish muscles recorded higher mean value (127.12mg/kg) for all heavy metals than tilapia (44.03mg/kg) and the sequence is Copper > Zinc > Iron > Cadmium. The concentration of heavy metals in Orashi River is in the sequence: Sediment > Catfish > Tilapia >Water. The Total Heavy metal concentration in muscle of Catfish (0.5-1.8mg/kg) and Tilapia (0.1-3.8mg/kg) were within permissible limit.