Increase in advanced electronic technology leads to environmental issues related with its disposal. Electronic waste i.e., video card and random access memory were used for studying extraction of precious metals using Paenibacillus sp. Metal contaminated soil was used for the isolation of exopolysaccharide producing strains. The isolate was identified as Paenibacillus sp. based on morphological, biochemical tests and 16S rRNA sequencing. Metal content analysis of soil and e-waste was carried out using X-ray Fluorescence spectroscopy. The vanadium element was more in the soil sample which was 0.487 mg/g and in electronic waste sample copper content was more which was 250 mg/g. Paenibacillus sp. produced capsule which was observed under bright, dark field and phase contrast microscope. Scanning electron microscopy was done for the study of morphological changes of exopolysaccharide producing Paenibacillus sp. in chitin broth and on chitin agar medium with and without e-waste. The Fourier Transform Infrared Spectroscopy analysis of exopolysaccharide produced by Paenibacillus sp. grown on chitin agar and chitin agar with e-waste showed presence of different functional groups. The one step and two step bioleaching experiments were carried out for testing efficacy of biomass on metal leaching. Paenibacillus sp. showed its potential for the extraction of precious metals viz., gold, silver and copper from electronic waste. Paenibacillus sp. recovered gold (0.001%), cadmium (45%), copper (50%), iron (46%), manganese (88%), palladium (56.9%) and zinc (87.12%) by two step fermentation. The study is useful for the bioleaching of precious metals from electronic waste.

Depending on their concentrations, sizes, and types, particulate matters of biological origins (bioPM) significantly affect human health. However, for different air environments, they are not well characterized and can vary considerably. As an example, we investigated the bioPM differences at an urban (Beijing) site and a rural (Wangdu) site in the North China Plain (NCP) using an online monitoring instrument, an ultraviolet aerodynamic particle sizer (UV-APS), the limulus amebocyte lysate (LAL) assay, and a high-throughput sequencing method. Generally, lower concentrations of viable bioPM (hourly mean: 1.3 × 10³ ± 1.6 × 10³ m⁻³) and endotoxin (0.66 ± 0.16 EU/m³) in Beijing were observed compared to viable bioPM (0.79 × 10⁵ ± 1.4 × 10⁵ m⁻³) and endotoxin (15.1 ± 23.96 EU/m³) at the Wangdu site. The percentage of viable bioPM number concentration in the total PM was 3.1% in Beijing and 6.4% in Wangdu. Approximately 80% of viable bioPM was found to be in the range from 1 to 2.5 μm. Nevertheless, the size distribution patterns for viable bioPM at the Beijing and Wangdu sites differed and were affected by PM pollution, leading to distinct lung deposition profiles. Moreover, the distinct diurnal variations in viable bioPM on clean days were dimmed by the PM pollution at both sites. Distinct bacterial community structures were found in the air from the Beijing and Wangdu sites. The bacterial community in urban Beijing was dominated by genus Lactococcus (49.5%) and Pseudomonas (15.1%), while the rural Wangdu site was dominated by Enterococcus (65%) and Paenibacillus (10%). Human-derived genera, including Myroides, Streptococcus, Propionibacterium, Dietzia, Helcococcus, and Facklamia, were higher in Beijing, suggesting bacterial emission from humans in the urban air environment. Our results show that different air harbors different biological species, and people residing in different environments thus could have very different biological particle exposure.

The distribution pattern of root-associated bacteria in native plant growth in tailing dumps with extreme conditions remains poorly understood and largely unexplored. Herein we chose a native plant, Bidens bipinnata, growing on both an Sb tailing dump (WKA) and adjacent normal soils (WKC) to in-depth understand the distribution pattern of root-associated bacteria and their responses on environmental factors. We found that the rhizosphere microbial diversity indices in the tailing dump were significantly different from that in the adjacent soil, and that such variation was significantly related with soil nutrients (TC, TOC, TN) and metal(loid) concentrations (Sb and As). Some dominant genera were significant enriched in WKA, suggesting their adaption to harsh environments. Notably, these genera are proposed to be involved in nutrient and metal(liod) cycling, such as nitrogen fixing (Devosia, Cellvibrio, Lysobacter, and Cohnella), P solubilizing (Flavobacterium), and Sb and As oxidation (Paenibacillus, Bacillus, Pseudomonas, and Thiobacillus). Our results suggest that certain root-associated bacteria in tailing dump were governed by soil edaphic factors and play important ecological roles in nutrient amendments and metal cycling for the successful colonization of Bidens bipinnata in this tailing dump.

Methyl tert-butyl ether (MTBE) degradation technologies based on two-phase partitioning systems such as extractive membrane biofilm reactors (EMBFR) permit separation of biological and contaminant compartments, thus allowing optimization of the biological section. In this study, we set-up an EMBFR with three MTBE-degrading and cooperating strains (termed social biofilm: Agrobacterium sp. MS2, Paenibacillus etheri SH7ᵀ and Rhodococcus ruber EE6). The removal efficiency of the social-biofilm EMBFR was 80%, and functional stability was observed in the reactor, i.e. more efficient than previous studies (single-strain inoculated EMBFR, <50% removal efficiency and unstable function). Metabolite tert-butyl alcohol was not observed, and the EC₅₀ values were higher than those observed in single-strain EMBFRs. Comparative analysis of the MTBE enzymatic pathway and the social-biofilm was performed, where the mechanism of cooperation observed within the social-biofilm is likely due to enzymatic redundancy. Functional outcomes were equal to previous batch tests, hence 100% scalability was obtained. Overall, higher functional and stability outcomes are obtained with the use of the social-biofilm in an MTBE-EMBFR.

Recent studies have indicated that Galleria mellonella larvae ingest polyethylene films and the degradation mechanism could inspire biotechnological exploitation for degrading plastic to eliminate global pollution from plastic waste. In this study, we tested the chemical compositions of masticated and ingested different plastic types by G. mellonella. High throughput sequencing of 16S rRNA gene was used to characterize the alteration of the microbial communities derived from salivary glands, gut contents and whole G. mellonella larvae. Our results indicated that G. mellonella is able to masticate polyethylene (PE), expanded polystyrene (EPS) and polypropylene (PP) and convert it to small particles with very large and chemically modified surfaces. The characteristics of the polymer affect the rate of damage. Formation of functional carbonyl groups on the appearance of oxidized metabolic intermediates of polyolefins in the frass samples observed. We found that the mastication of EPS, PP or PE could significantly alter the microbial composition in the gut content while it did not appear to influence the salivary glands microbial community. Representatives of Desulfovibrio vulgaris and Enterobacter grew with the PE diet while mastication of polystyrene and polypropylene increased the abundance of Enterococcus. The evaluation of bacterial communities in whole larvae confirmed the obtained result and additionally showed that the abundance of Paenibacillus, Corynebacterium and Commamonadaceae increased by Styrofoam (EPS) consumption.

Heavy metals (HM) are the major proximate drivers of pollution in the mangrove ecosystem. Therefore, ecological risk (ER) due to HM distribution/concentration in core-sediment of Puzi mangrove region (Taiwan) was examined with tidal influence (TI) along with indigenous rhizospheric bacteria (IRB). The HM concentration was observed higher at active-tidal-sediment compared to partially-active-sediment. Geo-accumulation index (Igₑₒ) and contamination factor (CF) indicated the tidal-sediment was highly contaminated with arsenic (As) and moderately contaminated with Lead (Pb) and Zinc (Zn). However, the pollution loading index (PLI) and degree of contamination (Cd) exhibited ‘no pollution’ and ‘low-moderate degree of contamination’, in the studied region respectively. The isolated IRB (Priestia megaterium, Bacillus safenis, Bacillus aerius, Bacillus subtilis, Bacillus velenzenesis, Bacillus lichenoformis, Kocuria palustris, Enterobacter hormaechei, Pseudomonus fulva, and Paenibacillus favisporus; accession number OM979069-OM979078) exhibited the arsenic resistant behavior with plant-growth-promoting characters (IAA, NH₃, and P-solubilization), which can be used in mangrove reforestation and bioremediation of HM.

Soil microbial communities play an important role in the biodegradation of different petroleum derivates, including hydrocarbons. Also other biological factors such as enzyme and respiration activities and microbial abundance are sensitive to contamination with petroleum derivates. The aim of this study was to evaluate the response of autochthonic microbial community and biological parameters (respiration, dehydrogenase and catalase activities, total microorganisms count) on contamination with car fuels and engine oils. The surface layer (0–20 cm) of Mollic Gleysol was used for the experiment. In laboratory conditions, soil was contaminated with the following petroleum substances: car fuels (petrol, diesel) and car engine oils (new and waste—after 10,000 km). The results demonstrated that, among the investigated hydrocarbon substances, petrol addition seemed to be the most toxic for the microbial activity of the investigated soil. The toxicity of the used hydrocarbon substances to microorganisms might be summarized as follows: diesel > new oil > waste oil > petrol. Species belonging to the genera Micrococcus and Rhodococcus were noted as the major autochthonic bacteria being present in soil contaminated with new automobile oil, whereas species of the genera Bacillus sp. and Paenibacillus sp. were identified in the combination treated with waste oil.

The current study aimed to devise eco-friendly, safe, and cost-effective strategies for enhanced degradation of low- and high-density polyethylene (LDPE and HDPE) using newly formulated thermophilic microbial consortia from cow dung and to assess the biodegradation end products. The plastic-degrading bacteria from cow dung samples gathered from highly plastic-acclimated environments were enriched by standard protocols. The degradation ability was comprehended by zone of clearance method, and the percentage of degradation was monitored by weight reduction process. The best isolates were characterized by standard microbiological and molecular biology protocols. The best isolates were employed to form several combinations of microbial consortia, and the degradation end products were analyzed. The stability of 16S ribosomal DNA (rDNA) was predicted by bioinformatics approach. This study identified 75 ± 2, 55 ± 2, 60 ± 3, and 43 ± 3% degradation for LDPE strips, pellets, HDPE strips, and pellets, respectively, for a period of 120 days (p < 0.05) at 55 °C by the formulated consortia of IS1-IS4, and the degradation efficiency was found to be better in comparison with other formulations. The end product analysis by Fourier transform infrared, scanning electron microscopy, energy-dispersive spectroscopy, and nuclear magnetic resonance showed major structural changes and formation of bacterial biofilm on plastic surfaces. These novel isolates were designated as Bacillus vallismortis bt-dsce01, Psuedomonas protegens bt-dsce02, Stenotrophomonas sp. bt-dsce03, and Paenibacillus sp.bt-dsce04 by 16S rDNA sequencing and suggested good gene stability with minimum Gibb’s free energy. Therefore, this study imparts substantial information regarding the utilization of these thermophilic microbial consortia from cow dung for rapid polyethylene removal.

The Janghang smelter in Chungnam, South Korea started in 1936 was subsequently shutdown in 1989 due to heavy metal (loid) pollution concerns in the vicinity. Thus, there is a need for the soil in the area to be remediated to make it usable again especially for agricultural purposes. The present study was conducted to exploit the potential of arsenic (As)-tolerant bacteria thriving in the vicinity of the smelter-polluted soils to enhance phytoremediation of hazardous As. We studied the genetic and taxonomic diversity of 21 As-tolerant bacteria isolated from soils nearer to and away from the smelter. These isolates belonging to the genera Brevibacterium, Pseudomonas, Microbacterium, Rhodococcus, Rahnella, and Paenibacillus, could tolerate high concentrations of arsenite (As(III)) and arsenate (As(V)) with the minimum inhibitory concentration ranging from 3 to >20 mM for NaAsO₂and 140 to 310 mM NaH₂AsO₄ · 7H₂O, respectively. All isolates exhibited As(V) reduction except Pseudomonas koreensis JS123, which exhibited both oxidation and reduction of As. Moreover, all the 21 isolates produced indole acetic acid (IAA), 13 isolates exhibited 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, 12 produced siderophore, 17 solubilized phosphate, and 13 were putative nitrogen fixers under in vitro conditions. Particularly, Rhodococcus aetherivorans JS2210, P. koreensis JS2214, and Pseudomonas sp. JS238 consistently increased root length of maize in the presence of 100 and 200 μM As(V). Possible utilization of these As-tolerant plant-growth-promoting bacteria can be a potential strategy in increasing the efficiency of phytoremediation in As-polluted soils.

Chromate-resistant bacterial strain isolated from the soil of tannery was studied for Cr(VI) bioaccumulation in free and immobilised cells to evaluate its applicability in chromium removal from aqueous solution. Based on the comparative analysis of the 16S rRNA gene, and phenotypic and biochemical characterization, this strain was identified as Paenibacillus xylanilyticus MR12. Mechanism of Cr adsorption was also ascertained by chemical modifications of the bacterial biomass followed by Fourier transform infrared spectroscopy analysis of the cell wall constituents. The equilibrium biosorption analysed using isotherms (Langmuir, Freundlich and Dubinin–Redushkevich) and kinetics models (pseudo-first-order, second-order and Weber–Morris) revealed that the Langmuir model best correlated to experimental data, and Weber–Morris equation well described Cr(VI) biosorption kinetics. Polyvinyl alcohol alginate immobilised cells had the highest Cr(VI) removal efficiency than that of free cells and could also be reused four times for Cr(VI) removal. Complete reduction of chromate in simulated effluent containing Cu²⁺, Mg²⁺, Mn²⁺ and Zn²⁺ by immobilised cells, demonstrated potential applications of a novel immobilised bacterial strain MR12, as a vital bioresource in Cr(VI) bioremediation technology.