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Further exploitation of the residual oil underground in post-polymer flooded reservoirs is attractive and challenging. Microbial-enhanced oil recovery (MEOR) is a promising strategy to enhance the recovery of residual oil in post-polymer flooded reservoirs. Identifying and selectively activating indigenous microorganisms with oil displacement capabilities is an urgent requirement in the current design of efficient microbial-enhanced oil recovery technologies. This study combines high-throughput sequencing with functional network analysis to identify the core functional microbes within the reservoirs. Concurrently, it devises targeted activation strategies tailored to oligotrophic conditions through an analysis of environmental factor influences. The feasibility of these strategies is then validated through physical simulation experiments. With nutrient stimulation, the overall diversity of microorganisms decreases while the abundance of functional microorganisms increases. The core displacement results showed that the oil recovery factor increased by 3.82% on the basis of polymer flooding. In summary, this research has established a system for the efficient activation of functional microorganisms under oligotrophic conditions by utilizing bioinformatics, network analysis, and indoor simulation systems. This achievement will undoubtedly lay a solid foundation for the practical implementation of microbial enhancement techniques in the field. [ABSTRACT FROM AUTHOR]

Microorganisms can affect coal biodegradation by driving elemental biogeochemical cycling. A detailed description of the sulfur conversion process led by indigenous bacteria during coal degradation is important. This study obtained sulfur-containing compounds conversion bacteria through indoor enrichment and conducted anaerobic culture experiments using coal supplemented with enriched bacteria. The study showed that the addition of enriched bacteria changed the microbial composition, particularly the microbial groups within Pseudomonadota and Bacillota. In addition, the sulfur-containing compounds conversion bacteria increased the pore volume and specific surface area of micropores (<10 nm) and transition pores (10–100 nm), as well changed the content of sulfur-containing organic components including polypeptides, aromatic compounds, alkyl compounds, and thiazoles. The genera related to inorganic sulfur conversion were mainly belonging to Bacillota and Actinomycetota. Additionally, functional genera that can degrade sulfur-containing organic compounds of dibenzothiophenes through the ring-opening of benzene rings were found within Pseudomonadota, Bacillota and Actinomycetota. In summary, organic sulfur-related Pseudomonadota, Bacillota and Actinomycetota and inorganic sulfur-related Bacillota and Actinomycetota detected in this study could accelerate the sulfur-containing compounds conversion and ultimately increase micropores in coal, and this holds great significance for understanding the biogeochemical cycling process of coal. [ABSTRACT FROM AUTHOR]

Indigenous microbial stimulation is considered as a highly promising technology for enhanced oil recovery (EOR) of low-permeability reservoirs. In this paper, oil components and microbial communities of indigenous microorganisms before and after bio-stimulation in the largest low-permeability oil field of China were discussed. The results showed that Pseudomonas aeruginosa was dominant in the original samples, followed by some sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB), such as Desulfovibrio oxyclinae, and Methylopila capsulata, Deferribacter abyssi. After bio-stimulation, the species of microorganisms gradually decreased, the content of Pseudomonas aeruginosa reached 2∼3 times than that of the original samples. The harmful bacteria, such as SRB and IRB, gradually disappeared. The Pr/Ph of the oil decreased, whereas the Pr/nC 17, Ph/nC 18, and ∑nC 21−/∑nC 22+increased. The average molecular weight of oil decreased after the microorganisms were stimulated, in which the contents of N1-containing compounds increased, and that of O1-containing compounds decreased. The contents of biphenyls, naphthalene, and its derivatives decreased. Whereas those of aromatic compounds, such as phenanthrene, quaternary, fluorene, and their homologs increased. Pilot study was applied in LD field block, the average water cut of 27–47 well group decreased from 87.60% to 74.86%, the oil production increased from 12.18 t/d to 29.58 t/d.

The preservation of microbial diversity is an issue not properly addressed, considering their role in shaping Earth into a habitable planet and their contribution to human well-being. The disturbance of their natural habitats triggers responses, which are reflected in the modification of microecosystem composition and metabolic activities. This is also the case with food-related microecosystems; changes in the growing environment, recorded as agricultural practices and manufacturing or storage conditions, result in similar alterations in the residing microcommunity. In fact, the principle aim of food microbiology is to favor the growth of health-promoting microorganisms and restrict the development of the ones that may negatively affect the quality of food or even cause infection or intoxication. Therefore, the current perspective is one-sided, disregarding issues of general interest, such as the preservation of actual biodiversity. The aim of the present article is to present the current food microbiology perspective, which is based on the different roles of food-related microbiota and highlight the need to move from an anthropocentric to a microbe-centric perception.

Biofilm, as a form of the microbial community in nature, represents an evolutionary adaptation to the influence of various environmental conditions. In nature, the largest number of microorganisms occur in the form of multispecies biofilms. The ability of microorganisms to form a biofilm is one of the reasons for antibiotic resistance. The creation of biofilms resistant to various contaminants, on the other hand, improves the biological treatment process in wastewater treatment plants. Heavy metals cannot be degraded, but they can be transformed into non-reactive and less toxic forms. In this process, microorganisms are irreplaceable as they interact with the metals in a variety of ways. The environment polluted by heavy metals, such as wastewater, is also a source of undiscovered microbial diversity and specific microbial strains. Numerous studies show that biofilm is an irreplaceable strategy for heavy metal removal. In this review, we systematize recent findings regarding the bioremediation potential of biofilm-forming microbial species isolated from diverse wastewaters for heavy metal removal. In addition, we include some mechanisms of action, application possibilities, practical issues, and future prospects. [ABSTRACT FROM AUTHOR]

Microbial inoculants are beneficial microorganisms applied to plants or the soil to promote plant growth and control pest disease and weeds. Microbial inoculants isolated from local surroundings are indigenous microorganisms (IMO) inoculants. The performance of the IMO inoculants is varied depending on the sources and the local environment. Therefore, it is important to identify the right sources to enhance the efficiency of the IMO inoculants. This research aims to study the performance of okra and soil by mixing potential yeast sources for indigenous microorganisms (IMO) inoculants. Longan and mango were chosen as the sources of yeasts. The IMO inoculants were fermented for a week, and the microorganisms group was identified. Then, the IMO inoculants were applied to the okra and tested for physical and mineral content analysis. IMO inoculants with mango and longan showed a higher yeast population than the control. However, IMO inoculants with mango showed the best plant growth and harvesting time performance. The soil treated with both IMO inoculants also showed higher potassium and calcium. To conclude, plants treated with both IMO inoculants performed better than the control. Thus, IMO inoculants with longan and mango may potentially enhance the yeast community in IMO inoculants, indirectly improving okra growth and benefiting the agriculture field in the future. [ABSTRACT FROM AUTHOR]

The preservation of microbial diversity is an issue not properly addressed, considering their role in shaping Earth into a habitable planet and their contribution to human well-being. The disturbance of their natural habitats triggers responses, which are reflected in the modification of microecosystem composition and metabolic activities. This is also the case with food-related microecosystems; changes in the growing environment, recorded as agricultural practices and manufacturing or storage conditions, result in similar alterations in the residing microcommunity. In fact, the principle aim of food microbiology is to favor the growth of health-promoting microorganisms and restrict the development of the ones that may negatively affect the quality of food or even cause infection or intoxication. Therefore, the current perspective is one-sided, disregarding issues of general interest, such as the preservation of actual biodiversity. The aim of the present article is to present the current food microbiology perspective, which is based on the different roles of food-related microbiota and highlight the need to move from an anthropocentric to a microbe-centric perception. [ABSTRACT FROM AUTHOR]

Stimulating indigenous microbes to reduce aqueous U(VI) to insoluble U(IV) by adding an electron donor has been applied as an applicable strategy to remediate uranium-contaminated groundwater in situ. However, biogenic U(IV) minerals are susceptible to oxidative remobilization after exposure to oxygen. To enhance the stability of the end product, glycerol phosphate (GP) was selected to treat artificial uranium-containing groundwater at different pH values (i.e., 7.0 and 5.0) with glycerol (GY) as the control group. The results revealed that removal ratios of uranium with GP were all higher than those with GY, and reduced crystalline U(IV)-phosphate and U(VI)-phosphate minerals (recalcitrant to oxidative remobilization) were generated in the GP groups. Although bioreduction efficiency was influenced at pH 5.0, the stability of the end product with GP was elevated significantly compared with that with GY. Mechanism analysis demonstrated that GP could activate bioreduction and biomineralization of the microbial community, and two stages were included in the GP groups. In the early stage, bioreduction and biomineralization were both involved in the immobilization process. Subsequently, part of the U(VI) precipitate was gradually reduced to U(IV) precipitate by microorganisms. This work implied that the formation of U-phosphate minerals via bioreduction coupled with biomineralization potentially offers a more effective strategy for remediating uranium-contaminated groundwater with long-term stability. [ABSTRACT FROM AUTHOR]

The goal of this study was to come up with an efficient method for treating cheese production wastewater. Because the effluent has a higher concentration of organic and inorganic materials, the indigenous microbial treatment process was used to effectively remove total dissolved solids (TDS), chemical oxygen demand (COD), and color without the addition of any nutrients. The indigenous microorganisms were tested for color, TDS, and COD elimination by growing them in "nutrient broth medium" loaded with different amounts of cheese effluent. The isolates were identified by 16S rRNA sequencing, and the results revealed that strain 1 was Enterobacter cloacae, strain 2 was Lactococcus garvieae, and strains 3 and 4 were Bacillus cereus and Bacillus mycoides, respectively. After 36 h of incubation, the data were evaluated. Among all the microbes, E. cloacae reduced TDS and COD from the effluent the most (80 ± 0.2% and 87 ± 0.4% COD, respectively). When compared to individual species, consortia were more efficient (86 ± 0.2% TDS and 90 ± 0.3% COD). On treatment, the correlation coefficient "r" for TDS and COD elimination was found to be 1, resulting in a positive linear connection. The current study suggests that microbial therapies are both effective and environmentally beneficial. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi that promote plant growth and nutrient acquisition are essential for nutrient-deficient karst areas, while they inevitably regulate host plants jointly with indigenous microorganisms in natural soil. However, how indigenous microorganisms regulate AM-induced benefits on plant growth and nutrient acquisition remains unclear. In this study, the Bidens tripartita as the common plant species in the karst region was cultivated into three soil substrates treated by AM fungi inoculation (AMF), AM fungi inoculation combining with indigenous microorganisms (AMI), and the control without AM fungi and indigenous microorganisms (CK). The plant biomass and concentration of nitrogen (N) and phosphorus (P) were measured, and the transcriptomic analysis was carried out using root tissues. The results showed that AM fungi significantly enhanced the plant biomass, N, and P accumulation with the reduction of plants' N/P ratio; however, the indigenous microorganisms offset the AM-induced benefits in biomass and N and P acquisition. In addition, there are 819 genes in differentially expressed genes (DEGs) of AMF vs. AMI ∩ AMF vs. CK , meaning that AM fungi induced these genes that were simultaneously regulated by indigenous microorganisms. Furthermore, the enrichment analysis suggested that these genes were significantly associated with the metabolic processes of organophosphate, P, sulfur, N, and arginine biosynthesis. Notably, 34 and 17 genes of DEGs were related to P and N metabolism, respectively. Moreover, the indigenous microorganisms significantly downregulated these DEGs, especially those encoding the PHO1 P transporters and the glnA, glutamate dehydrogenase 2 (GDH2), and urease as key enzymes in N assimilation; however, the indigenous microorganisms significantly upregulated genes encoding PHO84 inducing cellular response to phosphate (Pi) starvation. These regulations indicated that indigenous microorganisms restrained the N and P metabolism induced by AM fungi. In conclusion, we suggested that indigenous microorganisms offset nutrient benefits of AM fungi for host plants through regulating these genes related to P transport and N assimilation. [ABSTRACT FROM AUTHOR]

Understanding the behavior of arbuscular mycorrhizal fungi (AMF) associated with plants is essential for optimizing plant cultivation to the phytoremediation of degraded soils. The objective of the present study was to evaluate the differences in AMF root colonization between novel seed-based interspecific Miscanthus hybrids (M. sacchariflorus × M. sinensis) and the standard M. × giganteus when grown in soils contaminated with heavy metals (Pb, Cd, and Zn). During the third and fourth growing seasons, higher concentration of metals in the roots and a limited transfer of metals from the roots to the shoots were observed in all the plants studied. After the third growing season, the lowest values of AMF colonization rates were observed for the GNT34 hybrid. After the fourth growing season, AMF colonization decreased, which could be due to the drought that occurred during that season. GNT34 showed a lower tendency to develop mycorrhizal structures on heavy-metal (HM)-contaminated soils than GNT41 and M × g; however, this hybrid was insensitive to changes in colonization rates during the dry growing season. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi that promote plant growth and nutrient acquisition are essential for nutrient-deficient karst areas, while they inevitably regulate host plants jointly with indigenous microorganisms in natural soil. However, how indigenous microorganisms regulate AM-induced benefits on plant growth and nutrient acquisition remains unclear. In this study, the Bidens tripartita as the common plant species in the karst region was cultivated into three soil substrates treated by AM fungi inoculation (AMF), AM fungi inoculation combining with indigenous microorganisms (AMI), and the control without AM fungi and indigenous microorganisms (CK). The plant biomass and concentration of nitrogen (N) and phosphorus (P) were measured, and the transcriptomic analysis was carried out using root tissues. The results showed that AM fungi significantly enhanced the plant biomass, N, and P accumulation with the reduction of plants’ N/P ratio; however, the indigenous microorganisms offset the AM-induced benefits in biomass and N and P acquisition. In addition, there are 819 genes in differentially expressed genes (DEGs) of AMF vs. AMI ∩ AMF vs. CK, meaning that AM fungi induced these genes that were simultaneously regulated by indigenous microorganisms. Furthermore, the enrichment analysis suggested that these genes were significantly associated with the metabolic processes of organophosphate, P, sulfur, N, and arginine biosynthesis. Notably, 34 and 17 genes of DEGs were related to P and N metabolism, respectively. Moreover, the indigenous microorganisms significantly downregulated these DEGs, especially those encoding the PHO1 P transporters and the glnA, glutamate dehydrogenase 2 (GDH2), and urease as key enzymes in N assimilation; however, the indigenous microorganisms significantly upregulated genes encoding PHO84 inducing cellular response to phosphate (Pi) starvation. These regulations indicated that indigenous microorganisms restrained the N and P metabolism induced by AM fungi. In conclusion, we suggested that indigenous microorganisms offset nutrient benefits of AM fungi for host plants through regulating these genes related to P transport and N assimilation.

Naturally occurring attenuation process for restoration of crude oil impacted soil is dependent on the crude oil transformation capabilities of indigenous microorganisms that are ubiquitous in the soil. This potential of the microbes can be explored in the design of a emediation strategy to manage crude oil pollution in the soil. In this study, microbes including bacteria and fungi were isolated from an aged crude oil polluted soil and characterized using morphological and biochemical methods. The potential of the microbial isolates to utilize and degrade crude oil was evaluated in liquid medium using turbidity assay and estimation of total petroleum hydrocarbon (TPH). Microbial screening revealed the presence of microbial genera including bacteria and fungi in the aged crude oil polluted soil with ability to utilize and degrade crude oil in liquid medium. The probable identity of the indigenous microorganisms ranked in their increasing capacity to utilize and degrade crude oil was: Enterobacter ˂ E. coli ˂ Micrococcus ˂ Aeromonas ˂ Corynebacterium ˂ Bacillus ˂ Pseudomonas (bacteria) and Fusarium ˂ Penicillium ˂ Aspergillus (Fungi). These microbial isolates especially Pseudomonas, Bacillus, Aspergillus and Penicillium with high oleophilic abilities are effective candidates that can be used as microbial consortium in bioremediation plan for the restoration of the crude oil impacted soil.

The relevance of the study. The largest anthropogenic pressure associated with the exploitation of natural resources in the Tomsk region falls on the oil and gas industry. Geoecological analysis of the territory showed that the northern administrative regions are the most vulnerable areas, while the main factor in oil pollution of the soil is pipeline accidents. Bioremediation is a low-cost and environmentally friendly method of restoring contaminated areas. An effective approach to the bioremediation of oil-contaminated soils is isolation indigenous hydrocarbon-degrading microorganisms and creation biological products based on the strains. The main aim of the study is developing an industrial consortium based on indigenous hydrocarbon-oxidizing bacteria from soils of the North Tomsk Region and evaluating its effectiveness for bioremediation of oil-contaminated soils. Objects and methods. Cultures of indigenous hydrocarbon-oxidizing microorganisms were obtained under selective conditions from the crude oil contaminated soil sample, Soviet oil field, Tomsk Region. Isolated strains were identified using molecular genetic methods based on the analysis of 16S rRNA gene sequences. The physiological and biochemical properties of the isolates were studied by standard methods, and the morphology of the cells was studied microscopically. To assess the effectiveness of a biological product based on the selected strain, field tests were carried out in oil-contaminated areas. Quantitative chemical analysis for the total content of petroleum products in the soil was performed by fluorimetric method. Results. During the study, three novel strains of hydrocarbon-oxidizing bacteria belonging to the genera Acinetobacter and Oleomonas were isolated from oil-contaminated soils in the Tomsk Region and characterized. Indigenous microorganisms are characterized by reduced optimums of temperature and pH in comparison with type strains. Based on the identified microorganisms, a commercial biological product «Aborigen» was developed for bioremediation of oil-contaminated soils and wetlands. The experimental restoration of oil-contaminated soils with the help of a preparation of indigenous microorganisms-destructors has significantly reduced the time compared to self-restoration of soil cover during natural processes. Field tests showed high efficiency of oil destruction under the influence of a biological product – on average, in eight experimental sites, the total content of oil products in the soil was reduced 12,4 times in three months.

In the extreme environment of the cold and arid salt desert in northwest China, finding and discovering indigenous high-yielding urease microorganisms is the key to the research on the solidification and fixation of the surface salt desert soil or desert soil microenvironment. This paper takes the screening of salt-tolerant and high-producing urease microorganisms in the salt desert environment of the Qaidam Basin as the research objective. For the soil samples, water samples and salt-tolerant plants in the environment, techniques such as purification and separation, strain urease activity determination, and Berthelot reaction are used, to screen, isolate and identify an indigenous salt-tolerant high-producing urease microorganism, and further conduct the experimental study on the indigenous microbial flora, urease activity, mineralization ability and safety. The results showed that the indigenous salt-tolerant and high-producing urease microorganisms that were screened this time belonged to a kind of Staphylococcus xylosus, and its urease activity showed a peak change with the life cycle of the microorganisms, with the highest value of 2.24 U/mL, which belonged to the high-yielding microorganisms. The microorganism produces 8.6% of new calcium carbonate in a 10 mL induction solution with a soluble salt content of 7%, and possesses the ability of microbial mineralization. The indigenous salt-tolerant and high-yielding urease microorganisms screened out in the salt desert environment can be used for theoretical and technological innovation research on the prevention and control of microbial mineralization in the cold and dry salt desert in northwest China. [ABSTRACT FROM AUTHOR]

[Display omitted] • DICP ability of IM after optimization was stronger than the existing literature. • Degradation of EPS (especially carboxyl in EPS) ensures the formation of CaCO 3. • Bio-minerals formed through DICP significantly reduced the pore development of coal. • IM can resist the negative effects of CO 2 and induce minerals formation. • A conceptual application model of DICP in coal seam CO 2 storage was proposed. Carbon capture, utilization and storage (CCUS) is an effective means to achieve dual carbon goals. However, the leakage of CO 2 is a considerable risk. In this work, a new method was proposed to reduce the leakage of CO 2 in coal seam by denitrification induced carbonate precipitation (DICP) using indigenous microorganisms (IM). After enrichment and optimization, the mineralization efficiency of IM reached 90.47% and Pseudomonas was dominated. The degradation of negatively charged groups in extracellular polymeric substances (EPS), especially carboxyl, was essential to the formation of CaCO 3. The mineralization efficiency even increased under the presence of coal while the pore development was significantly reduced by the formed bio-minerals. The microflora was proven to resist the negative effects of CO 2 on bacterial growth and metabolism. Then, a conceptual model of industrial application was proposed. Our results demonstrated the good application potential of DICP technology in coal seam CO 2 geological storage. [ABSTRACT FROM AUTHOR]

The present experiment was conducted at Swine Production Farm, IVRI, Izatnagar, Bareilly (Uttar Pradesh) during month of December and March for the cultivation of Indigenous Microorganisms (IMOs) and its application in the composting of piggery excreta as a model for inoculated deep litter system of pig sty respectively in India. The IMOs were cultivated in four steps by using half-cooked rice, rice bran, soil and different energy sources, viz. brown sugar, jaggery, molasses in treatments C (Control), T1 and T2 groups, respectively. As a model of deep litter sty, aerobic composting of pig faeces, with different IMOs was conducted as treatments CC (brown Sugar), CT1 (jaggery), CT2 (molasses) and C0 (control) without any IMOs. During the experiment morning, evening, peak, mesophilic and thermophilic temperature distribution were recorded. The chemical composition and C: N ratio of pig faeces and compost were analysed at the end of experiment. The final compost temperature in all the treatment groups was in between 55 to 65°C but in control, it was higher than 65°C. The temperature range in treatment groups suggests that IMOs layers might have helped in decomposition process at faster rate which resultantly lowered the temperature. The carbon: nitrogen ratio (C: N) was significantly lower in CT1 and CT2 (19:1) than control indicative of good quality compost in treatment groups. It was concluded that IMOs from jaggary and molasses might be used as farmer friendly inocula/ inoculums to compost pig excreta under inoculated deep litter pig production system.

The present experiment was conducted on standardisation and categorization of Indigenous Microorganisms (IMOs) in India for its future application as inoculum in inoculated deep litter housing of pigs. The cultivation of IMOs was accomplished in four steps, which involved use of half cooked rice, sugar sources, rice bran and soil at 1st, 2nd, 3rd and 4th steps, respectively. The cultivated IMOs at the end of each step from 1st to 4th were named accordingly as IMO-1, IMO-2, IMO-3 and IMO-4. The cultivation of IMOs was done in three groups based on the major sources of energy at 2nd step as control (brown sugar), treatment 1 (Jaggery) and treatment 2 (Molasses). The IMO-1 was obtained after 7 days which was confirmed based on the appearance of white coloured fungal mycelium in all the groups. The IMO-4 was considered as the final product of cultivation process which was confirmed by the presence of fungal mycelium interwoven in the soil. IMO-4 stage was further categorised in different microbial groups based on laboratory examination and only two categories of microbes were witnessed namely bacteria and fungi, none of yeast were found in those inoculums. Out of four types of bacterial colonies, IMB-3 confirmed the presence of Paenibacillus amylolyticus and IMB-4 as Enterococcus casseliflavus. The standardisation of IMOs as inoculum for deep litter housing was performed first time in India.

Understanding the behavior of arbuscular mycorrhizal fungi (AMF) associated with plants is essential for optimizing plant cultivation to the phytoremediation of degraded soils. The objective of the present study was to evaluate the differences in AMF root colonization between novel seed-based interspecific Miscanthus hybrids (M. sacchariflorus × M. sinensis) and the standard M. × giganteus when grown in soils contaminated with heavy metals (Pb, Cd, and Zn). During the third and fourth growing seasons, higher concentration of metals in the roots and a limited transfer of metals from the roots to the shoots were observed in all the plants studied. After the third growing season, the lowest values of AMF colonization rates were observed for the GNT34 hybrid. After the fourth growing season, AMF colonization decreased, which could be due to the drought that occurred during that season. GNT34 showed a lower tendency to develop mycorrhizal structures on heavy-metal (HM)-contaminated soils than GNT41 and M × g; however, this hybrid was insensitive to changes in colonization rates during the dry growing season.

BACKGROUND: Diesel oil broad utilization has led to its dispersion in the environment. In this work, biostimulation and biostimulation coupled with autochthonous bioaugmentation were investigated for the bioremediation of soil artificially contaminated with diesel oil. RESULTS: Soil microcosms were prepared and monitored. The most effective strategy and the influence of glucose addition, both in soil or during the biomass 'enrichment' phase, were evaluated by means of respirometric analyses, microbial counts and residual contaminant concentration measurements. The respirometric activity was always higher in all microcosms contaminated with diesel oil than in the biotic controls. The presence of the contaminant did not inhibit the microbial activity. The microbial counts performed on diesel oil medium showed that the contaminant was prevalently biodegraded by the indigenous bacterial species. In terms of diesel oil degradation, similar results were obtained in biostimulated and bioaugmented microcosms; a degradation percentage in the range 65–70% after 34 days was achieved. The addition of glucose in soil, though favoring the growth of microorganisms, did not improve the degradation of contaminant. CONCLUSION: In this work, biostimulation, with no addition of a primary substrate, was the simplest and most cost‐effective strategy for the biodegradation of diesel oil. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study aims to evaluate the role of indigenous microorganisms in the mobilization of potentially toxic elements (PTE) and rare-earth elements (REE), the influence of the bioavailability of carbon sources that might boost microbial leaching, and the generation of neutral/alkaline mine drainage from alkaline tailings. These tailings, with significant concentrations of total organic carbon (TOC), were mainly colonized by bacteria belonging to the genera Sphingomonas, Novosphingobium and Solirubrobacter , and fungi of the genera Alternaria, Sarocladium and Aspergillus. Functionality analysis suggests the capability of these microorganisms to leach PTE and REE. Bio-/leaching tests confirmed the generation of neutral mine drainage, the influence of organic substrate, and the leaching of higher concentrations of PTE and REE due to the production of organic acids and siderophores by indigenous microorganisms. In addition, this study offers some insights into a sustainable alternative for reprocessing PMC alkaline tailings to recover REE. [Display omitted] • Indigenous microorganisms mobilise PTE and REE in alkaline mine wastes. • Organic carbon bioavailability accelerates microbial activity in alkaline tailings. • The concentration of TOC correlates with the mobilization of PTE and REE. • Indigenous microorganisms could be a sustainable alternative to recovering REE. • Bioleaching and TOC analysis should be included in environmental regulations. [ABSTRACT FROM AUTHOR]

Wastewater often contains an increased amount of mercury and, at the same time, resistant microorganisms. During wastewater treatment, a biofilm of indigenous microorganisms is often unavoidable. Therefore, the objective of this research is to isolate and identify microorganisms from wastewater and investigate their ability to form biofilms for possible application in mercury removal processes. The resistance of planktonic cells and their biofilms to the effects of mercury was investigated using Minimum Biofilm Eradication Concentration-High Throughput Plates. The formation of biofilms and the degree of resistance to mercury were confirmed in polystyrene microtiter plates with 96 wells. Biofilm on AMB Media carriers (Assisting Moving Bad Media) was quantified using the Bradford protein assay. The removal of mercury ions by biofilms formed on AMB Media carriers of selected isolates and their consortia was determined by a removal test in Erlenmeyer flasks simulating MBBR. All isolates in planktonic form showed some degree of resistance to mercury. The most resistant microorganisms (Enterobacter cloacae , Klebsiella oxytoca, Serratia odorifera , and Saccharomyces cerevisiae) were tested for their ability to form biofilms in the presence and absence of mercury, both in polystyrene plates and on ABM carriers. The results showed that among planktonic forms, K. oxytoca was the most resistant. A biofilm of the same microorganisms was more than 10-fold resistant. Most consortia biofilms had MBEC values > 100,000 μg/mL. Among individual biofilms, E. cloacae showed the highest mercury removal efficiency (97.81% for 10 days). Biofilm consortia composed of three species showed the best ability to remove mercury (96.64%–99.03% for 10 days). This study points to the importance of consortia of different types of wastewater microorganisms in the form of biofilms and suggests that they can be used to remove mercury in wastewater treatment bioreactors. [ABSTRACT FROM AUTHOR]

This study seeks to examine “in situ” remediation effectiveness of NPK fertilizer treatment as a viable biostimulation-based bioremediation technology for soil remediation by evaluating data obtained from soil physicochemical properties before and after initiation of bioremediation. Bioremediation was initiated by stimulating indigenous microorganisms in soil by NPK application while remediation was determined by soil physicochemical condition after nutrient amendment and changes observed in plant height after 60, 90, 120, 150, 180 and 210 days of planting. Rhizomes of turmeric were planted in soil treated with NPK fertilizer and control in a randomized complete block design (RCBD) with three replications. Data generated from soil physicochemical parameters in laboratory and field was analyzed before and after treatment. Study showed increase in available potassium, available phosphorus, total nitrogen, pH, cation exchange capacity (CEC) and organic carbon. However, there was decrease in aluminium, soil organic matter and acidity. Sand, silt and clay also decreased slightly. Study revealed significant increase in plant height from plants that benefitted from nutrient amendment.

Soil microorganisms play important roles in nutrient mobilization and uptake of mineral nutrition in plants. Agricultural management, such as soil sterilization, can have adverse effects on plant growth because of the elimination of indigenous microorganisms. Arbuscular mycorrhizal (AM) fungi are one of the most important beneficial soil microorganisms for plant growth. However, whether AM fungi can compensate for the loss of indigenous microbial communities to support plant growth and metabolism is largely unknown. In this study, a pot experiment was conducted to investigate the effects of AM fungi on plant growth and secondary metabolism in sterilized and unsterilized soil. We used liquorice (Glycyrrhiza uralensis Fisch.), an important medicinal plant as the host, which was inoculated with the AM fungus Rhizophagus irregularis or not and grown in unsterilized or sterilized soil. Plant photosynthesis traits, plant growth and nutrition level, concentrations of the secondary metabolites, and expression levels of biosynthesis genes were determined. The results showed that soil sterilization decreased plant growth, photosynthesis, and glycyrrhizin and liquiritin accumulation, and moreover, downregulated the expression of related biosynthesis genes. Inoculation with R. irregularis in sterilized soil offset the loss of indigenous microbial communities, resulting in plant growth and glycyrrhizin and liquiritin concentrations similar to those of plants grown in unsterilized soil. Thus, AM fungi could compensate for the loss of indigenous microbial communities by soil sterilization to support plant growth and secondary metabolism. [ABSTRACT FROM AUTHOR]

Bioremediation is an emerging and sustainable technique that can either occur naturally or be enhanced by introducing nutrients or bacteria able to degrade specific contaminants. In this study, the efficiencies of natural attenuation with nutrients, and bioaugmentation with nutrients and a consortium of five exogenous bacteria, were evaluated for total petroleum hydrocarbon (TPH) degradation in five highly contaminated soils from China, and Kuwait. The bioaugmentation treatment exhibited better efficiencies than the natural attenuation, and reached 48.10% of TPH degradation with a half-life of 41.76 d. The addition of exogenous bacteria also increased the removal of TPH in the highest contaminated soil sample. The concentration of TPH in that soil was reduced from 236, 500 mg kg−1 of dry soil to 176, 566 mg kg−1 of dry soil in 40 d, which was equivalent to 25.4% degradation of TPH. The degradation rate (1501.8 mg kg−1d−1 of TPH) was higher than those reported in previous studies with a lower concentration of TPH. The bioaugmented strains could withstand high concentrations of TPH and thrive in five different types of soils. Consequently, these strains can be used to remediate soils that are heavily contaminated with petroleum hydrocarbons. • Bioaugmentation with exogenous bacteria enhanced the degradation of TPH. • A higher degradation rate of TPH was observed in the highest contaminated sample. • The average half-life of TPH among all samples was reduced to 84.6 days. • Strains used are suitable for in situ bioremediation of highly contaminated sites. [ABSTRACT FROM AUTHOR]

The aim of work was to check and make comparison of efficacy for five approaches for petroleum crude contaminated agricultural soil remediation by making use of soil microcosms. Concerning the published literature in our information, this is the first report comparing five approaches i.e. abiotic losses, native microbial flora, nutrient amendments and pre-adapted native microbial culture and concurrent amendments of nutrients + pre-adapted native microbial culture for agricultural soil bioremediation using Pseudomonas aeruginosa NCIM 5514 by performing soil microcosm experiments. 96.00 ± 0.18% degradation of petroleum hydrocarbon fractions in 60 days of the experiment was observed when nutrients and P. aeruginosa NCIM 5514 were applied concomitantly. In nutrients- and P. aeruginosa NCIM 5514-added microcosm reduction in nitrogen, organic carbon, and phosphorus was noted. P. aeruginosa NCIM 5514, can be applied as a prospective bioremediation agent to remediate petroleum crude contaminated soil. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of autochthonous microorganisms present in soil collected from heavy metal (HM) uncontaminated (Pb ≈ 59 mg kg−1, Cd ≈ 0.4 mg kg−1, Zn ≈ 191 mg kg−1), moderately (Pb ≈ 343 mg kg−1, Cd ≈ 12 mg kg−1, Zn ≈ 1876 mg kg−1), and highly (Pb ≈ 1586 mg kg−1, Cd ≈ 57 mg kg−1, Zn ≈ 3280 mg kg−1) contaminated sites on Zea mays elemental composition, physiological status, and growth parameters. For this purpose, half of the collected soil was sterilized and soil characterization was performed. After 45 days of cultivation, the presence of HM in the soil negatively affected photosynthesis and transpiration rates, relative chlorophyll content, anthocyanins index, chlorophyll fluorescence parameters, and content of oxidative stress products (H2O2 and Malondialdehyde) of Zea mays, while soil sterilization had a positive effect on those parameters. Average percentage of colonization of root segments by arbuscular mycorrhiza fungi decreased with an increase of HM contamination in the soil. The increase in shoot concentration of HMs, particularly Cd and Zn, was a result of contaminated soils sterilization. Aboveground biomass of maize cultivated on sterilized soil was 3-fold, 1.5-fold, and 1.5-fold higher for uncontaminated, moderately contaminated and highly contaminated soils respectively when compared to nonsterilized soils. Contrary to our expectation, autochthonous microflora did not improve plant growth and photosynthetic performance; in fact, they had a negative effect on those processes although they did reduce concentration of HMs in the shoots grown on contaminated soils. [ABSTRACT FROM AUTHOR]

The impact of indigenous microorganisms on the mineral corrosion and mineral trapping in the SO2 co-injected CO2-saline-sandstone interaction was investigated in this study by lab experiments under 55 °C, 15 M pa. The results verified that co-injection of SO2 resulted in a decrease in biomass and shifts in microbial communities within 90 days, but some microorganisms still could adapt to acidic, high-temperature, high-pressure, and high-salinity environments. Firmicutes and Proteobacteria remained dominant phylum, but phylum Proteobacteria showed better tolerance to the co-injection of SO2 in the initial period. In the SO2 co-injected CO2-saline-sandstone interaction under microbial mediation, acid-producing bacteria further promoted the corrosion of K-feldspar, albite, and clay minerals, meanwhile mobilizing more K+, Na+, Ca2+, Mg2+ into solution. The acidogenic effect may be linked to the dominant genus of Bacillus, Paenibacillus, Acinetobacter, Pseudomonas and Exiguobacterium. Co-injection of SO2 inhibited the carbonates capture, while microbial acid production further reduced the pH, further inhibiting carbonates capture. As a result, no secondary carbonate (e.g., calcite) was observed on a short time scale within 90 days. So, microbial acidogenic effect was not conducive to carbonates capture in short term. [ABSTRACT FROM AUTHOR]

To get a better knowledge on how archaeal communities differ between the oil and aqueous phases and whether environmental factors promote substantial differences on microbial distributions among production wells, we analyzed archaeal communities in oil and aqueous phases from four high-temperature petroleum reservoirs (55–65°C) by using 16S rRNA gene based 454 pyrosequencing. Obvious dissimilarity of the archaeal composition between aqueous and oil phases in each independent production wells was observed, especially in production wells with higher water cut, and diversity in the oil phase was much higher than that in the corresponding aqueous phase. Statistical analysis further showed that archaeal communities in oil phases from different petroleum reservoirs tended to be more similar, but those in aqueous phases were the opposite. In the high-temperature ecosystems, temperature as an environmental factor could have significantly affected archaeal distribution, and archaeal diversity raised with the increase of temperature (p < 0.05). Our results suggest that to get a comprehensive understanding of petroleum reservoirs microbial information both in aqueous and oil phases should be taken into consideration. The microscopic habitats of oil phase, technically the dispersed minuscule water droplets in the oil could be a better habitat that containing the indigenous microorganisms.

Abstract The unique physiochemical properties exhibited by rare earth elements (REEs) and their increasing application in high-tech industries has created a demand for secure supply lines with established recovery procedures that create minimal environmental damage. Bioleaching experiments conducted on a non-sterile monazite concentrate with a known phosphate solubilising microorganism (PSM) resulted in greater mobilisation of REEs into solution in comparison to experiments conducted on sterile monazite. By combining the native consortia with an introduced PSM, a syntrophic effect between the populations effectively leached a greater amount of REEs than either a single PSM or the indigenous population alone. With sterile monazite, Penicillium sp.CF1 inoculated experiments released a total REE concentration of 12.32 mg L−1 after incubation for 8 days, whereas on non-sterile ore, double the soluble REE concentration was recorded (23.7 mg L−1). Comparable effects were recorded with Enterobacter aerogenes , Pantoea agglomerans and Pseudomonas putida. Alterations in the microbial populations during bioleaching of the monazite ore were determined by diversity profiling and demonstrated noticeable changes in community inhabitants over 14 days. The presence of native Firmicutes on the monazite appears to greatly contribute to the increased leaching recorded when using non-sterile monazite for REE recovery. [ABSTRACT FROM AUTHOR]

Algae can use excessive nutrients from wastewater effluent to generate beneficial products such as biofuels. However, fluctuation of wastewater characteristics could hinder the implementation of tertiary algal treatment. This study aims to identify the impact of nutrient availability on Chlorella vulgaris's ability to remove nitrogen and phosphorus from wastewater, and its potential as a biofuel feedstock. Experiments using synthetic wastewater with varying concentrations of nitrate and phosphate showed C. vulgaris continued to remove either nutrient when the other was exhausted. Nitrogen starvation led the algae to accumulate the highest amount of neutral lipid; however, the exhaustion of phosphorus did not produce such impact. Synergistic effect was also observed between C. vulgaris and indigenous microorganisms in nutrient removal from real wastewater effluent. The results showed C. vulgaris can survive in a range of nutrient-limiting conditions, making tertiary algal treatment applicable following various secondary treatment regimes. [ABSTRACT FROM AUTHOR]

In regard to highly poisonous effects of cyanide ion, concerns have been focused recently on treatment of such compounds in different ways. Four bacterial strains (C1-C4) capable of using cyanide as nitrogen source were isolated from contaminated gold mine soil samples under alkaline conditions at 30 °C, pH 9.5-10.5, and agitation speed 150 rpm. The gram-negative bacterium C3 (identified as Pseudomonas parafulva NBRC 16636(T) by 16S rRNA gene sequencing) was able to tolerate cyanide up to 500 ppm besides removing 93.5% of 200 ppm cyanide in 13 days which was confirmed by microorganisms growth. The addition of basal salts enhanced the removal efficiency of C3 by 16%. Cyanide removal efficiency of co-culture was 30% less than C3. Optimization of three significant parameters including temperature, pH, and glucose concentration for cyanide biodegradation was studied using response surface methodology (RSM). The optimum conditions for maximizing cyanide biodegradation were temperature (32.23 °C), pH (9.95), and glucose concentration (0.73 g/l). [ABSTRACT FROM AUTHOR]

In situ bioremediation (ISB) using reductive dechlorination is a widely accepted but relatively slow approach compared to other technologies for the treatment of groundwater contaminated by chlorinated ethenes (CVOCs). Due to the known positive kinetic effect on microbial metabolism, thermal enhancement may be a viable means of accelerating ISB. We tested thermally enhanced ISB in aquifers situated in sandy saprolite and underlying fractured granite. The system comprised pumping, heating and subsequent injection of contaminated groundwater aiming at an aquifer temperature of 20–30 °C. A fermentable substrate (whey) was injected in separate batches. The test was monitored using hydrochemical and molecular tools (qPCR and NGS). The addition of the substrate and increase in temperature resulted in a rapid increase in the abundance of reductive dechlorinators (e.g., Dehalococcoides mccartyi , Dehalobacter sp. and functional genes vcrA and bvcA ) and a strong increase in CVOC degradation. On day 34, the CVOC concentrations decreased by 87% to 96% in groundwater from the wells most affected by the heating and substrate. On day 103, the CVOC concentrations were below the LOQ resulting in degradation half-lives of 5 to 6 days. Neither an increase in biomarkers nor a distinct decrease in the CVOC concentrations was observed in a deep well affected by the heating but not by the substrate. NGS analysis detected Chloroflexi dechlorinating genera ( Dehalogenimonas and GIF9 and MSBL5 clades) and other genera capable of anaerobic metabolic degradation of CVOCs. Of these, bacteria of the genera Acetobacterium , Desulfomonile , Geobacter , Sulfurospirillum , Methanosarcina and Methanobacterium were stimulated by the substrate and heating. In contrast, groundwater from the deep well (affected by heating only) hosted representatives of aerobic metabolic and aerobic cometabolic CVOC degraders. The test results document that heating of the treated aquifer significantly accelerated the treatment process but only in the case of an abundant substrate. [ABSTRACT FROM AUTHOR]

Microalgal biofilm cultivation is a promising method for efficient microalgae production. However, expensive, difficult-to-obtain and non-durable carriers hinder its up-scaling. This study adopted both sterilized and unsterilized rice straw (RS) as a carrier for the development of microalgal biofilm, with polymethyl methacrylate as control. The biomass production and chemical composition of Chlorella sorokiniana , as well as the microbial community composition during cultivation were examined. The physicochemical properties of RS before and after utilized as carrier were investigated. The biomass productivity of unsterilized RS biofilm exceeded that of suspended culture by 4.85 g m−2·d−1. The indigenous microorganisms, mainly fungus, could effectively fixed microalgae to the bio-carrier and enhance its biomass production. They could also degrade RS into dissolved matters for microalgal utilization, leading to the physicochemical properties change of RS in the direction which favored its energy conversion. This study showed that RS can be used effectively as a microalgal biofilm carrier, thus presenting a new possibility for the recycling of rice straw. [Display omitted] • Algal biomass from raw rice straw exceeded suspended culture by 4.85 g m−2·d−1. • Indigenous microorganisms effectively fixed Chlorella sorokiniana on rice straw. • Indigenous microorganisms could degrade rice straw for microalgae growth. • Rice straw was pretreated during biofilm culture which avails energy conversion. [ABSTRACT FROM AUTHOR]

The increase of anthropogenic activities and growth of technology in Antarctica is fuelled by the high demand for petroleum hydrocarbons needed for daily activities. Oil and fuel spills that occur during explorations have caused hydrocarbon pollution in this region, prompting concern for the environment by polar communities and the larger world community. Crude oil and petroleum hydrocarbon products contain a wide variety of lethal components with high toxicity and low biodegradability. Hydrocarbon persistence in the Antarctic environment only worsens the issues stemming from environmental pollution as they can be long-term. Numerous efforts to lower the contamination level caused by these pollutants have been conducted mainly in bioremediation, an economical and degrading-wise method. Bioremediation mainly functions on conversion of complex toxic compounds to simpler organic compounds due to the consumption of hydrocarbons by microorganisms as their energy source. This review presents a summary of the collective understanding on bioremediation of petroleum hydrocarbons by microorganisms indigenous to the Antarctic region from past decades to current knowledge. [ABSTRACT FROM AUTHOR]

The indigenous microorganisms responsible for degrading phenanthrene (PHE) in activated biosludge were identified using DNA-based stable isotope probing. Besides the well-known PHE degraders Burkholderia, Ralstonia, Sinobacteraceae and Arthrobacter, we for the first time linked the taxa Paraburkholderia and Kaistobacter with in situ PHE biodegradation. Analysis of PAH-RHD gene detected in the heavy DNA fraction of C-PHE treatment suggested the mechanisms of horizontal gene transfer or inter-species hybridisation in PAH-RHD gene spread within the microbial community. Additionally, three cultivable PHE degraders, Microbacterium sp. PHE-1, Rhodanobacter sp. PHE-2 and Rhodococcus sp. PHE-3, were isolated from the same activated biosludge. Among them, Rhodanobacter sp. PHE-2 is the first identified strain in its genus with PHE-degrading ability. However, the involvement of these strains in PHE degradation in situ was questionable, due to their limited enrichment in the heavy DNA fraction of C-PHE treatment and lack of PAH-RHD gene found in these isolates. Collectively, our findings provide a deeper understanding of the diversity and functions of indigenous microbes in PHE degradation. [ABSTRACT FROM AUTHOR]

Biomolecular and hydrochemical tools were used to evaluate natural attenuation of chlorinated ethenes in a Quaternary alluvial aquifer located close to a historical source of large-scale tetrachloroethylene (PCE) contamination. Distinct stratification of redox zones was observed, despite the aquifer's small thickness (2.8 m). The uppermost zone of the target aquifer was characterised by oxygen- and nitrate-reducing conditions, with mixed iron- to sulphate-reducing conditions dominant in the lower zone, along with indications of methanogenesis. Natural attenuation of PCE was strongly influenced by redox heterogeneity, while higher levels of PCE degradation coincided with iron- to sulphate reducing conditions. Next generation sequencing of the middle and/or lower zones identified anaerobic bacteria (Firmicutes, Chloroflexi, Actinobacteria and Bacteroidetes) associated with reductive dechlorination. The relative abundance of dechlorinators ( Dehalococcoides mccartyi , Dehalobacter sp.) identified by real-time PCR in soil from the lower levels supports the hypothesis that there is a significant potential for reductive dechlorination of PCE. Local conditions were insufficiently reducing for rapid complete dechlorination of PCE to harmless ethene. For reliable assessment of natural attenuation, or when designing monitoring or remedial systems, vertical stratification of key biological and hydrochemical markers should be analysed as standard, even in shallow aquifers. [ABSTRACT FROM AUTHOR]