Simultaneous heterotrophic nitrification and aerobic denitrification potential of Paenibacillus sp. strain GLM-08 isolated from lignite mine waste and its role ammonia removal from mine waste water

Role of ammonia-oxidising bacteria in the removal of odorous gases by the use of plastic recycling waste as a biofilter

Ammonia gas has emerged as a major concern for many industrial facilities. With the same degree of hazard, plastic waste after mechanical processing is becoming a crucial challenge for many mechanical plastics recycling plants. In this respect, the present study explored the use of plastic waste obtained from mechanical recycling plants as an adsorbent to treat ammonia gas using a biofiltration device. The physical-chemical parameters of the adsorbent used, notably moisture, ash, organic matter, pH and elemental analysis were determined. Next-generation sequencing and scanning electron microscopy analyses were carried out to detect and identify the nature of bacterial communities in the biofilters used. The results of the chemical analysis showed that the adsorbent used is appropriate for the development of the microorganisms. X-ray fluorescence analysis showed that the adsorbent belongs to the silico-aluminous materials, proving its effectiveness as an adsorbent. The efficiency of ammonia removal was over 93% using the biofilter. Next-generation sequencing revealed that bacteria belonging to ammonia oxidizers such as Nitrosomonas and Nitrosospira are among the most abundant bacteria after the biofiltration process, which explains the efficiency of ammonia removal. Scanning electron microscopy confirmed the development of a biofilm on the surface of the biofilter after filtration. Ultimately, these results offer a promising novel approach for valorisation of the plastic waste.

MICP mediated by indigenous bacteria isolated from tailings for biocementation for reduction of wind erosion

In this study, native ureolytic bacteria were isolated from copper tailings soils to perform microbial-induced carbonate precipitation (MICP) tests and evaluate their potential for biocement formation and their contribution to reduce the dispersion of particulate matter into the environment from tailings containing potentially toxic elements. It was possible to isolate a total of 46 bacteria; among them only three showed ureolytic activity: Priestia megaterium T130-1, Paenibacillus sp. T130-13 and Staphylococcus sp. T130-14. Biocement cores were made by mixing tailings with the isolated bacteria in presence of urea, resulting similar to those obtained with Sporosarcina pasteurii and Bacillus subtilis used as positive control. Indeed, XRD analysis conducted on biocement showed the presence of microcline (B. subtilis 17%; P. megaterium 11. 9%), clinochlore (S. pasteurii, 6.9%) and magnesiumhornblende (Paenibacillus sp. 17.8%; P. megaterium 14.6%); all these compounds were not initially present in the tailings soils. Moreover the presence of calcite (control 0.828%; Paenibacillus sp. 5.4%) and hematite (control 0.989%; B. subtilis 6.4%) was also significant unlike the untreated control. The development of biofilms containing abundant amount of Ca, C, and O on microscopic soil particles was evidenced by means of FE-SEM-EDX and XRD. Wind tunnel tests were carried out to investigate the resistance of biocement samples, accounted for a mass loss five holds lower than the control, i.e., the rate of wind erosion in the control corresponded to 82 g/m2h while for the biocement treated with Paenibacillus sp. it corresponded to only 16.371 g/m2h. Finally, in compression tests, the biocement samples prepared with P. megaterium (28.578 psi) and Paenibacillus sp. (28.404 psi) showed values similar to those obtained with S. pasteurii (27.102 psi), but significantly higher if compared to the control (15.427 psi), thus improving the compression resistance capacity of the samples by 85.2% and 84.1% with respect to the control. According to the results obtained, the biocement samples generated with the native strains showed improvements in the mechanical properties of the soil supporting them as potential candidates in applications for the stabilization of mining liabilities in open environments using bioaugmentation strategies with native strains isolated from the same mine tailing.

Culturable heterotrophic bacterial diversity study from an Indian lignite mine habitat

Diversity lifts the productivity of any ecosystem as all the species have a vital role to play that is present within the ecosystem. The characterization is essential to delve into the ecological functions of microbial communities and discover the type of microorganisms present within the ecosystem. As microbial diversity in ecosystems responds to environmental disturbances, it functions as a marker to indicate the change in such ecosystems. Mine ecology differs significantly from other habitats due to the presence of acidic runoff. This paper provides insight into the diversity of cultivable bacteria isolated from lignite mines located in south Gujarat. A total of 67 heterotrophic isolates were successfully cultivated from the collected solid and water samples of the Rajpardi and Tadkeshwar Lignite mine sites. The isolates were characterized morphologically and biochemically, and intra- and extracellular enzyme synthesis were studied. Moreover, the relative density and frequency of cultivated isolates from the samples were calculated. The similarity and evenness of the heterotrophic isolated were studied by calculating diversity indices such as Shannon and Simpson. Alpha diversity was calculated in PAST software to analyse the similarity between the selected two mine sites. This research also explored the relationship between the variance in heterotrophic microbial diversity and substrate utilization richness of the studied lignite mines of Gujarat.