From Rare to Dominant: a Fine-Tuned Soil Bacterial Bloom during Petroleum Hydrocarbon Bioremediation

Degradation of crude oil by mixed cultures of bacteria isolated from the Qinghai-Tibet plateau and comparative analysis of metabolic mechanisms

This study investigates the biodegradation of crude oil by a mixed culture of bacteria isolated from the Qinghai-Tibet plateau using gas chromatography-mass spectrometer (GC-MS) and the gravimetric method. The results showed that a mixed culture has a stronger ability to degrade hydrocarbon than pure cultures. Once both Nocardia soli Y48 and Rhodococcus erythropolis YF28-1 (8) were present in a culture, the culture demonstrated the highest crude oil removal efficiency of almost 100% after 10 days of incubation at 20 °C. Moreover, further analysis of the degradation mechanisms used by the above strains, which revealed utilization of different n-alkane substrates, indicated the diversity of evolution and variations in different strains, as well as the importance of multiple metabolic mechanisms for alkane degradation. Therefore, it is concluded that a mixed culture of Y48 and YF28-1 (8) strains can provide a more effective method for bioremediation of hydrocarbon-contaminated soil in permafrost regions.

Petroleum Hydrocarbon-Degrading Bacteria for the Remediation of Oil Pollution Under Aerobic Conditions: A Perspective Analysis

With the sharp increase in population and modernization of society, environmental pollution resulting from petroleum hydrocarbons has increased, resulting in an urgent need for remediation. Petroleum hydrocarbon-degrading bacteria are ubiquitous in nature and can utilize these compounds as sources of carbon and energy. Bacteria displaying such capabilities are often exploited for the bioremediation of petroleum oil-contaminated environments. Recently, microbial remediation technology has developed rapidly and achieved major gains. However, this technology is not omnipotent. It is affected by many environmental factors that hinder its practical application, limiting the large-scale application of the technology. This paper provides an overview of the recent literature referring to the usage of bacteria as biodegraders, discusses barriers regarding the implementation of this microbial technology, and provides suggestions for further developments.

Complete Genome Sequence of the Hydrocarbon-Degrading Strain Achromobacter sp. B7, Isolated during Petroleum Hydrocarbon Bioremediation in the Valparaiso Region, Chile

Achromobacter sp. strain B7 (= CCUG 72081) was isolated from a diesel-polluted soil from the Valparaiso Region, Chile, subjected to bioremediation with a hydrocarbon-degrading enrichment.

Achromobacter sp. strain B7 (= CCUG 72081) was isolated from a diesel-polluted soil from the Valparaiso Region, Chile, subjected to bioremediation with a hydrocarbon-degrading enrichment. The complete genome sequence of Achromobacter sp. B7 has been determined to have a size of 6.24 Mb, 5,578 coding sequences, 57 tRNAs, and a G+C content of 64.8%.

Living at the Frontiers of Life: Extremophiles in Chile and Their Potential for Bioremediation

Extremophiles are organisms capable of adjust, survive or thrive in hostile habitats that were previously thought to be adverse or lethal for life. Chile gathers a wide range of extreme environments: salars, geothermal springs, and geysers located at Altiplano and Atacama Desert, salars and cold mountains in Central Chile, and ice fields, cold lakes and fjords, and geothermal sites in Patagonia and Antarctica. The aims of this review are to describe extremophiles that inhabit main extreme biotopes in Chile, and their molecular and physiological capabilities that may be advantageous for bioremediation processes. After briefly describing the main ecological niches of extremophiles along Chilean territory, this review is focused on the microbial diversity and composition of these biotopes microbiomes. Extremophiles have been isolated in diverse zones in Chile that possess extreme conditions such as Altiplano, Atacama Desert, Central Chile, Patagonia, and Antarctica. Interesting extremophiles from Chile with potential biotechnological applications include thermophiles (e.g., Methanofollis tationis from Tatio Geyser), acidophiles (e.g., Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum from Atacama Desert and Central Chile copper ores), halophiles (e.g., Shewanella sp. Asc-3 from Altiplano, Streptomyces sp. HKF-8 from Patagonia), alkaliphiles (Exiguobacterium sp. SH31 from Altiplano), xerotolerant bacteria (S. atacamensis from Atacama Desert), UV- and Gamma-resistant bacteria (Deinococcus peraridilitoris from Atacama Desert) and psychrophiles (e.g., Pseudomonas putida ATH-43 from Antarctica). The molecular and physiological properties of diverse extremophiles from Chile and their application in bioremediation or waste treatments are further discussed. Interestingly, the remarkable adaptative capabilities of extremophiles convert them into an attractive source of catalysts for bioremediation and industrial processes.

Petroleum hydrocarbon rich oil refinery sludge of North-East India harbours anaerobic, fermentative, sulfate-reducing, syntrophic and methanogenic microbial populations

Background

Sustainable management of voluminous and hazardous oily sludge produced by petroleum refineries remains a challenging problem worldwide. Characterization of microbial communities of petroleum contaminated sites has been considered as the essential prerequisite for implementation of suitable bioremediation strategies. Three petroleum refinery sludge samples from North Eastern India were analyzed using next-generation sequencing technology to explore the diversity and functional potential of inhabitant microorganisms and scope for their on-site bioremediation.

Results

All sludge samples were hydrocarbon rich, anaerobic and reduced with sulfate as major anion and several heavy metals. High throughput sequencing of V3-16S rRNA genes from sludge metagenomes revealed dominance of strictly anaerobic, fermentative, thermophilic, sulfate-reducing bacteria affiliated to Coprothermobacter, Fervidobacterium, Treponema, Syntrophus, Thermodesulfovibrio, Anaerolinea, Syntrophobacter, Anaerostipes, Anaerobaculum, etc., which have been well known for hydrocarbon degradation. Relatively higher proportions of archaea were detected by qPCR. Archaeal 16S rRNA gene sequences showed presence of methanogenic Methanobacterium, Methanosaeta, Thermoplasmatales, etc. Detection of known hydrocarbon utilizing aerobic/facultative anaerobic (Mycobacterium, Pseudomonas, Longilinea, Geobacter, etc.), nitrate reducing (Gordonia, Novosphigobium, etc.) and nitrogen fixing (Azovibrio, Rhodobacter, etc.) bacteria suggested niche specific guilds with aerobic, facultative anaerobic and strict anaerobic populations. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) predicted putative genetic repertoire of sludge microbiomes and their potential for hydrocarbon degradation; lipid-, nitrogen-, sulfur- and methane- metabolism. Methyl coenzyme M reductase A (mcrA) and dissimilatory sulfite reductase beta-subunit (dsrB) genes phylogeny confirmed methanogenic and sulfate-reducing activities within sludge environment endowed by hydrogenotrophic methanogens and sulfate-reducing Deltaproteobacteria and Firmicutes members.

Conclusion

Refinery sludge microbiomes were comprised of hydrocarbon degrading, fermentative, sulfate-reducing, syntrophic, nitrogen fixing and methanogenic microorganisms, which were in accordance with the prevailing physicochemical nature of the samples. Analysis of functional biomarker genes ascertained the activities of methanogenic and sulfate-reducing organisms within sludge environment. Overall data provided better insights on microbial diversity and activity in oil contaminated environment, which could be exploited suitably for in situ bioremediation of refinery sludge.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1275-8) contains supplementary material, which is available to authorized users.

Diversity and Niche of Archaea in Bioremediation

Bioremediation is the use of microorganisms for the degradation or removal of contaminants. Most bioremediation research has focused on processes performed by the domain Bacteria; however, Archaea are known to play important roles in many situations. In extreme conditions, such as halophilic or acidophilic environments, Archaea are well suited for bioremediation. In other conditions, Archaea collaboratively work alongside Bacteria during biodegradation. In this review, the various roles that Archaea have in bioremediation is covered, including halophilic hydrocarbon degradation, acidophilic hydrocarbon degradation, hydrocarbon degradation in nonextreme environments such as soils and oceans, metal remediation, acid mine drainage, and dehalogenation. Research needs are addressed in these areas. Beyond bioremediation, these processes are important for wastewater treatment (particularly industrial wastewater treatment) and help in the understanding of the natural microbial ecology of several Archaea genera.

Community dynamics and functional characteristics of naphthalene-degrading populations in contaminated surface sediments and hypoxic/anoxic groundwater

Earlier research on the biogeochemical factors affecting natural attenuation in coal-tar contaminated groundwater, at South Glens Falls, NY, revealed the importance of anaerobic metabolism and trophic interactions between degrader and bacterivore populations. Field-based characterizations of both phenomena have proven challenging, but advances in stable isotope probing (SIP), single-cell imaging and shotgun metagenomics now provide cultivation-independent tools for their study. We tracked carbon from ¹³ C-labelled naphthalene through microbial populations in contaminated surface sediments over 6 days using respiration assays, secondary ion mass spectrometry imaging and shotgun metagenomics to disentangle the contaminant-based trophic web. Contaminant-exposed communities in hypoxic/anoxic groundwater were contrasted with those from oxic surface sediments to identify putative features of anaerobic catabolism of naphthalene. In total, six bacteria were responsible for naphthalene degradation. Cupriavidus, Ralstonia and Sphingomonas predominated at the earliest stages of SIP incubations and were succeeded in later stages by Stenotrophomonas and Rhodococcus. Metagenome-assembled genomes provided evidence for the ecological and functional characteristics underlying these temporal shifts. Identical species of Stenotrophomonas and Rhodococcus were abundant in the most contaminated, anoxic groundwater. Apparent increases in bacterivorous protozoa were observed following exposure to naphthalene, though insignificant amounts of carbon were transferred between bacterial degraders and populations of secondary feeders.

Potential microbial consortium involved in the biodegradation of diesel, hexadecane and phenanthrene in mangrove sediment explored by metagenomics analysis

Hydrocarbon contamination is a serious problem that degrades the quality of mangrove ecosystems, and bioremediation using autochthonous bacteria is a promising technology to recover an impacted environment. This research investigates the biodegradation rates of diesel, hexadecane and phenanthrene, by conducting a microcosm study and survey of the autochthonous microbial community in contaminated mangrove sediment, using an Illumina MiSeq platform. The biodegradation rates of diesel, hexadecane and phenanthrene were 82, 86 and 8 mg kg^-1 sediment day^-1, respectively. The removal efficiencies of hexadecane and phenanthrene were >99%, whereas the removal efficiency of diesel was 88%. A 16S rRNA gene amplicon sequence analysis revealed that the major bacterial assemblages detected were Gammaproteobacteria, Deltaproteobacteria, Alphaproteobacteria. The bacterial compositions were relatively constant, while reductions of the supplemented hydrocarbons were observed. The results imply that the autochthonous microorganisms in the mangrove sediment were responsible for the degradation of the respective hydrocarbons. Diesel-, hexadecane- and phenanthrene-degrading bacteria, namely Bacillus sp., Pseudomonas sp., Acinetobacter sp. and Staphylococcus sp., were also isolated from the mangrove sediment. The mangrove sediment provides a potential resource of effective hydrocarbon-degrading bacteria that can be used as an inoculum or further developed as a ready-to-use microbial consortium for the purpose of bioremediation.

Aerobic bacteria degrading both n-alkanes and aromatic hydrocarbons: an undervalued strategy for metabolic diversity and flexibility

Environmental pollution with petroleum toxic products has afflicted various ecosystems, causing devastating damage to natural habitats with serious economic implications. Some crude oil components may serve as growth substrates for microorganisms. A number of bacterial strains reveal metabolic capacities to biotransform various organic compounds. Some of the hydrocarbon degraders are highly biochemically specialized, while the others display a versatile metabolism and can utilize both saturated aliphatic and aromatic hydrocarbons. The extended catabolic profiles of the latter group have been subjected to systematic and complex studies relatively rarely thus far. Growing evidence shows that numerous bacteria produce broad biochemical activities towards different hydrocarbon types and such an enhanced metabolic potential can be found in many more species than the already well-known oil-degraders. These strains may play an important role in the removal of heterogeneous contamination. They are thus considered to be a promising solution in bioremediation applications. The main purpose of this article is to provide an overview of the current knowledge on aerobic bacteria involved in the mineralization or transformation of both n-alkanes and aromatic hydrocarbons. Variant scientific approaches enabling to evaluate these features on biochemical as well as genetic levels are presented. The distribution of multidegradative capabilities between bacterial taxa is systematically shown and the possibility of simultaneous transformation of complex hydrocarbon mixtures is discussed. Bioinformatic analysis of the currently available genetic data is employed to enable generation of phylogenetic relationships between environmental strain isolates belonging to the phyla Actinobacteria, Proteobacteria, and Firmicutes. The study proves that the co-occurrence of genes responsible for concomitant metabolic bioconversion reactions of structurally-diverse hydrocarbons is not unique among various systematic groups.

Conditionally Rare Taxa Contribute but Do Not Account for Changes in Soil Prokaryotic Community Structure

The rare biosphere is predicted to aid in maintaining functional redundancy as well as contributing to community turnover across many environments. Recent developments have partially confirmed these hypotheses, while also giving new insights into dormancy and activity among rare communities. However, less attention has been paid to the rare biosphere in soils. This study provides insight into the rare biosphere’s contribution to soil microbial diversity through the study of 781 soil samples representing 24 edaphically diverse sites. Results show that Bray–Curtis dissimilarity for time-sensitive conditionally rare taxa (CRT) does not correlate with whole community dissimilarity, while dissimilarity for space-sensitive CRT only weakly correlate with whole community dissimilarity. This adds to current understanding of spatiotemporal filtering of rare taxa, showing that CRT do not account for community variance across tested soils, but are under the same selective pressure as the whole community.

Biostimulation and bioaugmentation of native microbial community accelerated bioremediation of oil refinery sludge

Scope for developing an engineered bioremediation strategy for the treatment of hydrocarbon-rich petroleum refinery waste was investigated through biostimulation and bioaugmentation approaches. Enhanced (46-55%) total petroleum hydrocarbon (TPH) attenuation was achieved through phosphate, nitrate or nitrate+phosphate amendment in the sludge with increased (upto 12%) abundance of fermentative, hydrocarbon degrading, sulfate-reducing, CO₂-assimilating and methanogenic microorganisms (Bacillus, Coprothermobacter, Rhodobacter, Pseudomonas, Achromobacter, Desulfitobacter, Desulfosporosinus, T78, Methanobacterium, Methanosaeta, etc). Together with nutrients, bioaugmentation with biosurfactant producing and hydrocarbon utilizing indigenous Bacillus strains resulted in 57-75% TPH reduction. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis revealed enhanced gene allocation for transporters (0.45-3.07%), ABC transporters (0.38-2.07%), methane (0.16-1.06%), fatty acid (0.018-0.15%), nitrogen (0.07-0.17%), butanoate (0.06-0.35%), propanoate (0.004-0.26%) metabolism and some xenobiotics (0.007-0.13%) degradation. This study indicated that nutrient-induced community dynamics of native microorganisms and their metabolic interplay within oil refinery sludge could be a driving force behind accelerated bioremediation.

Decomposer food web in a deciduous forest shows high share of generalist microorganisms and importance of microbial biomass recycling

Forest soils represent important terrestrial carbon (C) pools where C is primarily fixed in the plant-derived biomass but it flows further through the biomass of fungi and bacteria before it is lost from the ecosystem as CO₂ or immobilized in recalcitrant organic matter. Microorganisms are the main drivers of C flow in forests and play critical roles in the C balance through the decomposition of dead biomass of different origins. Here, we track the path of C that enters forest soil by following respiration, microbial biomass production, and C accumulation by individual microbial taxa in soil microcosms upon the addition of ¹³C-labeled biomass of plant, fungal, and bacterial origin. We demonstrate that both fungi and bacteria are involved in the assimilation and mineralization of C from the major complex sources existing in soil. Decomposer fungi are, however, better suited to utilize plant biomass compounds, whereas the ability to utilize fungal and bacterial biomass is more frequent among bacteria. Due to the ability of microorganisms to recycle microbial biomass, we suggest that the decomposer food web in forest soil displays a network structure with loops between and within individual pools. These results question the present paradigms describing food webs as hierarchical structures with unidirectional flow of C and assumptions about the dominance of fungi in the decomposition of complex organic matter.

Bioaugmentation of thiabendazole-contaminated soils from a wastewater disposal site: Factors driving the efficacy of this strategy and the diversity of the indigenous soil bacterial community

The application of the fungicide thiabendazole (TBZ) in fruit packaging plants (FPP) results in the production of effluents which are often disposed in adjacent field sites. These require remediation to prevent further environmental dispersal of TBZ. We assessed the bioaugmentation potential of a newly isolated TBZ-degrading bacterial consortium in a naturally contaminated soil (NCS) exhibiting a natural gradient of TBZ levels (12000, 400, 250 and 12 mg kg^-1). The effect of aging on bioaugmentation efficacy was comparatively tested in a soil with similar physicochemical properties and soil microbiota, which was artificially, contaminated with the same TBZ levels (ACS). The impact of bioaugmentation and TBZ on the bacterial diversity in the NCS was explored via amplicon sequencing. Bioaugmentation effectively removed TBZ from both soils at levels up to 400 mg kg^-1 but failed at the highest contamination level (12000 mg kg^-1). Dissipation of TBZ in bioaugmented samples showed a concentration-dependent pattern, while aging of TBZ had a slight effect on bioaugmentation efficiency. Bioaugmentation had no impact on the soil bacterial diversity, in contrast to TBZ contamination. Soils from the hotspots of TBZ contamination (12000 mg kg^-1) showed a drastically lower α-diversity driven by the dominance of β- and γ-proteobacteria at the expense of all other bacterial phyla, especially Actinobacteria. Overall, bioaugmentation with specialized microbial inocula could be an effective solution for the recovery of disposal sites contaminated with persistent chemicals like TBZ.

Diversity-Function Relationships in Natural, Applied, and Engineered Microbial Ecosystems

The connection between ecosystem function and taxonomic diversity has been of interest and relevance to macroecologists for decades. After many years of lagging behind due to the difficulty of assigning both taxonomy and function to poorly distinguishable microscopic cells, microbial ecology now has access to a suite of powerful molecular tools which allow its practitioners to generate data relating to diversity and function of a microbial community on an unprecedented scale. Instead, the problem facing today's microbial ecologists is coupling the ease of generation of these datasets with the formulation and testing of workable hypotheses relating the diversity and function of environmental, host-associated, and engineered microbial communities. Here, we review the current state of knowledge regarding the links between taxonomic alpha- and beta-diversity and ecosystem function, comparing our knowledge in this area to that obtained by macroecologists who use more traditional techniques. We consider the methodologies that can be applied to study these properties and how successful they are at linking function to diversity, using examples from the study of model microbial ecosystems, methanogenic bioreactors (anaerobic digesters), and host-associated microbiota. Finally, we assess ways in which our newly acquired understanding might be used to manipulate diversity in ecosystems of interest in order to improve function for the benefit of us or the environment in general through the provision of ecosystem services.

A confidence interval analysis of sampling effort, sequencing depth, and taxonomic resolution of fungal community ecology in the era of high-throughput sequencing

High-throughput sequencing technology has helped microbial community ecologists explore ecological and evolutionary patterns at unprecedented scales. The benefits of a large sample size still typically outweigh that of greater sequencing depths per sample for accurate estimations of ecological inferences. However, excluding or not sequencing rare taxa may mislead the answers to the questions ‘how and why are communities different?’ This study evaluates the confidence intervals of ecological inferences from high-throughput sequencing data of foliar fungal endophytes as case studies through a range of sampling efforts, sequencing depths, and taxonomic resolutions to understand how technical and analytical practices may affect our interpretations. Increasing sampling size reliably decreased confidence intervals across multiple community comparisons. However, the effects of sequencing depths on confidence intervals depended on how rare taxa influenced the dissimilarity estimates among communities and did not significantly decrease confidence intervals for all community comparisons. A comparison of simulated communities under random drift suggests that sequencing depths are important in estimating dissimilarities between microbial communities under neutral selective processes. Confidence interval analyses reveal important biases as well as biological trends in microbial community studies that otherwise may be ignored when communities are only compared for statistically significant differences.

Divergent extremes but convergent recovery of bacterial and archaeal soil communities to an ongoing subterranean coal mine fire

Press disturbances are stressors that are extended or ongoing relative to the generation times of community members, and, due to their longevity, have the potential to alter communities beyond the possibility of recovery. They also provide key opportunities to investigate ecological resilience and to probe biological limits in the face of prolonged stressors. The underground coal mine fire in Centralia, Pennsylvania has been burning since 1962 and severely alters the overlying surface soils by elevating temperatures and depositing coal combustion pollutants. As the fire burns along the coal seams to disturb new soils, previously disturbed soils return to ambient temperatures, resulting in a chronosequence of fire impact. We used 16S rRNA gene sequencing to examine bacterial and archaeal soil community responses along two active fire fronts in Centralia, and investigated the influences of assembly processes (selection, dispersal and drift) on community outcomes. The hottest soils harbored the most variable and divergent communities, despite their reduced diversity. Recovered soils converged toward similar community structures, demonstrating resilience within 10–20 years and exhibiting near-complete return to reference communities. Measured soil properties (selection), local dispersal, and neutral community assembly models could not explain the divergences of communities observed at temperature extremes, yet beta-null modeling suggested that communities at temperature extremes follow niche-based processes rather than null. We hypothesize that priority effects from responsive seed bank transitions may be key in explaining the multiple equilibria observed among communities at extreme temperatures. These results suggest that soils generally have an intrinsic capacity for robustness to varied disturbances, even to press disturbances considered to be ‘extreme', compounded, or incongruent with natural conditions.

Metagenomic insights into effects of spent engine oil perturbation on the microbial community composition and function in a tropical agricultural soil

Analyzing the microbial community structure and functions become imperative for ecological processes. To understand the impact of spent engine oil (SEO) contamination on microbial community structure of an agricultural soil, soil microcosms designated 1S (agricultural soil) and AB1 (agricultural soil polluted with SEO) were set up. Metagenomic DNA extracted from the soil microcosms and sequenced using Miseq Illumina sequencing were analyzed for their taxonomic and functional properties. Taxonomic profiling of the two microcosms by MG-RAST revealed the dominance of Actinobacteria (23.36%) and Proteobacteria (52.46%) phyla in 1S and AB1 with preponderance of Streptomyces (12.83%) and Gemmatimonas (10.20%) in 1S and Geodermatophilus (26.24%), Burkholderia (15.40%), and Pseudomonas (12.72%) in AB1, respectively. Our results showed that soil microbial diversity significantly decreased in AB1. Further assignment of the metagenomic reads to MG-RAST, Cluster of Orthologous Groups (COG) of proteins, Kyoto Encyclopedia of Genes and Genomes (KEGG), GhostKOALA, and NCBI's CDD hits revealed diverse metabolic potentials of the autochthonous microbial community. It also revealed the adaptation of the community to various environmental stressors such as hydrocarbon hydrophobicity, heavy metal toxicity, oxidative stress, nutrient starvation, and C/N/P imbalance. To the best of our knowledge, this is the first study that investigates the effect of SEO perturbation on soil microbial communities through Illumina sequencing. The results indicated that SEO contamination significantly affects soil microbial community structure and functions leading to massive loss of nonhydrocarbon degrading indigenous microbiota and enrichment of hydrocarbonoclastic organisms such as members of Proteobacteria and Actinobacteria.

Microbial changes linked to the accelerated degradation of the herbicide atrazine in a range of temperate soils

Accelerated degradation is the increased breakdown of a pesticide upon its repeated application, which has consequences for the environmental fate of pesticides. The herbicide atrazine was repeatedly applied to soils previously untreated with s-triazines for >5 years. A single application of atrazine, at an agriculturally relevant concentration, was sufficient to induce its rapid dissipation. Soils, with a range of physico-chemical properties and agricultural histories, showed similar degradation kinetics, with the half-life of atrazine decreasing from an average of 25 days after the first application to <2 days after the second. A mathematical model was developed to fit the atrazine-degrading kinetics, which incorporated the exponential growth of atrazine-degrading organisms. Despite the similar rates of degradation, the repertoire of atrazine-degrading genes varied between soils. Only a small portion of the bacterial community had the capacity for atrazine degradation. Overall, the microbial community was not significantly affected by atrazine treatment. One soil, characterised by low pH, did not exhibit accelerated degradation, and atrazine-degrading genes were not detected. Neutralisation of this soil restored accelerated degradation and the atrazine-degrading genes became detectable. This illustrates the potential for accelerated degradation to manifest when conditions become favourable. Additionally, the occurrence of accelerated degradation under agriculturally relevant concentrations supports the consideration of the phenomena in environmental risk assessments.

Technological Approach of Bioremediation Using Microbial Tools

Bioremediation is applied to eliminate various contaminants, such as organic, inorganic or other pollutants from the environment. Environment worldwide is under great stress due to industrialization and human interfering on the limited natural resources. The release of chemicals pollution needs several techniques to treat some of these chemicals, but due to their cost, new technologies should be developing in order to create cost-effective and eco-friendly bioremediation technologies for environmental conversions. Bioremediation is an increasingly popular using microbial and algae strains for degrading waste contaminants. It is using of microorganisms and its enzymes to protect the environment from severe pollution. Bioremediation may be employed in order to eliminate specific contaminants, such as chlorinated pesticides or other pollutants from the environment. Microorganisms degrade the different pollutants in a natural environment but some modifications can be done to enhance its degradation efficiency at a faster rate in a limited time frame by using the genetically engineered microorganisms and microalgae. In this chapter, the role of the bacteria, fungi and algae in bioremediation of different environmental pollutants was highlighted.

Microbial Communities in Sediments of Lagos Lagoon, Nigeria: Elucidation of Community Structure and Potential Impacts of Contamination by Municipal and Industrial Wastes

Estuarine sediments are significant repositories of anthropogenic contaminants, and thus knowledge of the impacts of pollution upon microbial communities in these environments is important to understand potential effects on estuaries as a whole. The Lagos lagoon (Nigeria) is one of Africa’s largest estuarine ecosystems, and is impacted by hydrocarbon pollutants and other industrial and municipal wastes. The goal of this study was to elucidate microbial community structure in Lagos lagoon sediments to identify groups that may be adversely affected by pollution, and those that may serve as degraders of environmental contaminants, especially polycyclic aromatic hydrocarbons (PAHs). Sediment samples were collected from sites that ranged in types and levels of anthropogenic impacts. The sediments were characterized for a range of physicochemical properties, and microbial community structure was determined by Illumina sequencing of the 16S rRNA genes. Microbial diversity (species richness and evenness) in the Apapa and Eledu sediments was reduced compared to that of the Ofin site, and communities of both of the former two were dominated by a single operational taxonomic unit (OTU) assigned to the family Helicobacteraceae (Epsilonproteobacteria). In the Ofin community, Epsilonproteobacteria were minor constituents, while the major groups were Cyanobacteria, Bacteroidetes, and Firmicutes, which were all minor in the Apapa and Eledu sediments. Sediment oxygen demand (SOD), a broad indicator of contamination, was identified by multivariate analyses as strongly correlated with variation in alpha diversity. Environmental variables that explained beta diversity patterns included SOD, as well as levels of naphthalene, acenaphthylene, cobalt, cadmium, total organic matter, or nitrate. Of 582 OTU identified, abundance of 167 was significantly correlated (false discovery rate q≤ 0.05) to environmental variables. The largest group of OTU correlated with PAH levels were PAH/hydrocarbon-degrading genera of the Oceanospirillales order (Gammaproteobacteria), which were most abundant in the hydrocarbon-contaminated Apapa sediment. Similar Oceanospirillales taxa are responsive to marine oil spills and thus may present a unifying theme in marine microbiology as bacteria adapted for degradation of high hydrocarbon loads, and may represent a potential means for intrinsic remediation in the case of the Lagos lagoon sediments.