Autochthonous Microbial Consortia Research Articles

Impact of soil amendment using indigenous inoculants on tomato growth and yield parameters

Tomato (Lycopersicon esculentum mill) is one of the most important vegetable crops in the world. It is widely acknowledged that using composts and microbial inoculants as soil amendments, rather than industrialized fertilizer and raw manure, could improve soil nutrients, promote soil health and consequently improve crop yields. Global population increase necessitates increasing crop yields. Improvement and maintenance of soil fertility is essential via bio-augmentation in this economic recovery era. In this work, an open field experiment was conducted in other to study the "Yield Effects of Indigenous Microbial Inoculants on Tomato using autochthonous microbial consortia”. The experiment was laid in Randomized complete Block Design (RCBD) with three replicate consisted of six inoculants samples; Indigenous cultures viz; (A) Control, (B)Bacillus mucilaginosus (C) Azospirillum sp., (D) Azotobacter sp. (E) Commercial strains of the inoculants (F) Consortium of B, C and D. The various morphological features/yields parameters measured at intervals includes; no. of leaves, plant height, root length, accumulated dry matter and average fruit weight. The result shows that indigenous inoculants (F) increased tomato overall yield. This research is also of great significance for the development of management strategies for soil maintenance, environmental protection, and resource conservation in Nigeria where soil fertility is on the decrease due to over-use of land in other to achieve food security. From the result of the research, it can be concluded that soil augmentation with indigenous inoculants improves tomato morphological features and yields, hence should be preferred above their exotic commercial strain counterparts because of cost of importation/indigenous product development and GDP growth.

Development of an Autochthonous Microbial Consortium for Enhanced Bioremediation of PAH-Contaminated Soil.

The main objectives of this study were to isolate bacteria from soil chronically contaminated with polycyclic aromatic hydrocarbons (PAHs), develop an autochthonous microbial consortium, and evaluate its ability to degrade PAHs in their native contaminated soil. Strains with the best bioremediation potential were selected during the multi-stage isolation process. Moreover, to choose bacteria with the highest bioremediation potential, the presence of PAH-degrading genes (pahE) was confirmed and the following tests were performed: tolerance to heavy metals, antagonistic behavior, phytotoxicity, and antimicrobial susceptibility. In vitro degradation of hydrocarbons led to the reduction of the total PAH content by 93.5% after the first day of incubation and by 99.22% after the eighth day. Bioremediation experiment conducted in situ in the contaminated area resulted in the average reduction of the total PAH concentration by 33.3% after 5 months and by over 72% after 13 months, compared to the concentration recorded before the intervention. Therefore, this study implicates that the development of an autochthonous microbial consortium isolated from long-term PAH-contaminated soil has the potential to enhance the bioremediation process.

New Insights into Controlling Homoacetogenesis in the Co-digestion of Coffee Waste: Effect of Operational Conditions and Characterization of Microbial Communities.

In this research batch reactors were operated with coffee processing waste and autochthonous microbial consortium, and a taxonomic and functional analysis was performed for phase I of stabilization of maximum H2 production and for phase II of maximum H2 consumption. During phase I, the reactor's operating conditions were pH 4.84 to 8.18, headspace 33.18% to 66.82%, and pulp and husk from 6.95 to 17.05g/L. These assays continued for phase II, with initial pH conditions of 5.8-8.1, headspace of 33.18-66.82%, and pulp and husk remaining from phase I. The highest homoacetogenesis was observed in assay 5 with pH 7.7, 40% headspace, and 15g/L of pulp and husk (initial concentrations of phase I). A relative abundance of Clostridium 41%, Lactobacillus 20% and Acetobacter 14% was observed in phase I. In phase II, there was a change in relative abundance of 21%, 63%, and 1%, respectively, and functional genes involved with autotrophic (formyltetrahydrofolate synthase) and heterotrophic (enolase) homoacetogenesis, butanol (3-hydroxybutyryl-CoA dehydrogenase), and propionic acid (propionate CoA-transferase) were identified. This study provides a new and amplified insight into the physicochemical and microbiological factors, which can be used to propose adequate operational conditions to maximize the bioenergy production and reduce homoacetogenesis in biological reactors.

Improving sustainable hydrogen production from green waste: [FeFe]-hydrogenases quantitative gene expression RT-qPCR analysis in presence of autochthonous consortia

BackgroundBio-hydrogen production via dark fermentation of low-value waste is a potent and simple mean of recovering energy, maximising the harvesting of reducing equivalents to produce the cleanest fuel amongst renewables. Following several position papers from companies and public bodies, the hydrogen economy is regaining interest, especially in combination with circular economy and the environmental benefits of short local supply chains, aiming at zero net emission of greenhouse gases (GHG). The biomasses attracting the largest interest are agricultural and urban green wastes (pruning of trees, collected leaves, grass clippings from public parks and boulevards), which are usually employed in compost production, with some concerns over the GHG emission during the process. Here, an alternative application of green wastes, low-value compost and intermediate products (partially composted but unsuitable for completing the process) is studied, pointing at the autochthonous microbial consortium as an already selected source of implementation for biomass degradation and hydrogen production. The biocatalysts investigated as mainly relevant for hydrogen production were the [FeFe]-hydrogenases expressed in Clostridia, given their very high turnover rates.ResultsBio-hydrogen accumulation was related to the modulation of gene expression of multiple [FeFe]-hydrogenases from two strains (Clostridium beijerinckii AM2 and Clostridium tyrobutyricum AM6) isolated from the same waste. Reverse Transcriptase quantitative PCR (RT-qPCR) was applied over a period of 288 h and the RT-qPCR results showed that C. beijerinckii AM2 prevailed over C. tyrobutyricum AM6 and a high expression modulation of the 6 different [FeFe]-hydrogenase genes of C. beijerinckii in the first 23 h was observed, sustaining cumulative hydrogen production of 0.6 to 1.2 ml H2/g VS (volatile solids). These results are promising in terms of hydrogen yields, given that no pre-treatment was applied, and suggested a complex cellular regulation, linking the performance of dark fermentation with key functional genes involved in bio-H2 production in presence of the autochthonous consortium, with different roles, time, and mode of expression of the involved hydrogenases.ConclusionsAn applicative outcome of the hydrogenases genes quantitative expression analysis can be foreseen in optimising (on the basis of the acquired functional data) hydrogen production from a nutrient-poor green waste and/or low added value compost, in a perspective of circular bioeconomy.

Microbial degradation of Cold Lake Blend and Western Canadian select dilbits by freshwater enrichments

Treatability experiments were conducted to determine the biodegradation of diluted bitumen (dilbit) at 5 and 25 °C for 72 and 60 days, respectively. Microbial consortia obtained from the Kalamazoo River Enbridge Energy spill site were enriched on dilbit at both 5 (cryo) and 25 (meso) ºC. On every sampling day, triplicates were sacrificed and residual hydrocarbon concentrations (alkanes and polycyclic aromatic hydrocarbons) were determined by GCMS/MS. The composition and relative abundance of different bacterial groups were identified by 16S rRNA gene sequencing analysis. While some physicochemical differences were observed between the two dilbits, their biodegradation profiles were similar. The rates and extent of degradation were greater at 25 °C. Both consortia metabolized 99.9% of alkanes; however, the meso consortium was more effective at removing aromatics than the cryo consortium (97.5 vs 70%). Known hydrocarbon-degrading bacteria were present in both consortia (Pseudomonas, Rhodococcus, Hydrogenophaga, Parvibaculum, Arthrobacter, Acidovorax), although their relative abundances depended on the temperatures at which they were enriched. Regardless of the dilbit type, the microbial community structure significantly changed as a response to the diminishing hydrocarbon load. Our results demonstrate that dilbit can be effectively degraded by autochthonous microbial consortia from sites with recent exposure to dilbit contamination.

Consorcio microbiano autóctono para el tratamiento de aguas contaminadas con gasoil del puerto de Isla de Toas (Venezuela)

El tratamiento biológico de aguas contaminadas mediante consorcios microbianos autóctonos, aprovecha las potencialidades metabólicas de grupos distintos de microorganismos para degradar y/o remover una amplia variedad de compuestos. Adicionalmente, las técnicas de bioestimulación y bioaumentación contribuyen a potenciar las capacidades de estos procesos de biodegradación. El objetivo de este trabajo consistió en evaluar la utilización de un consorcio microbiano autóctono (Chlorella spp.-bacterias) para el tratamiento de aguas del puerto de Isla de Toas (Lago de Maracaibo, Venezuela), contaminadas con 1% v/v de gasoil. Para ello, se usaron dos tratamientos (T1: bioestimulado y T2: bioaumentado) y un control por 70 días, a escala de 20 L y condiciones ambientales controladas. Durante los ensayos se monitorearon: temperatura, pH, demanda química de oxígeno (DQO), nitrito, nitrato, nitrógeno total Kjeldahl, nitrógeno total (N-total), ortofosfato, fósforo total (P-total), hidrocarburos totales del petróleo (HTP), fracciones de hidrocarburos (SARA), densidad microalgal y bacteriana, y pigmentos fotosintéticos, de acuerdo con los métodos estandarizados. Los valores medios para la remoción de materia orgánica (DQO), N-total y P-total, fueron: 23,3±2,3; 35,2±4,5 y 64,6±4,8%, de 27,6±1,64; 79,8±2,05 y 87,7±1,95%, y de <0,1; 16,1±0,38 y 44,7±1,18%, para el control, T1 y T2, respectivamente. Las concentraciones finales de HTP estuvieron por encima del límite permisible de la normativa venezolana para descarga a cuerpos de aguas naturales, no obstante, se obtuvieron altas tasas de remoción de hidrocarburos saturados y aromáticos (>70%), particularmente en el tratamiento bioaumentado (T2). Los consorcios microbianos autóctonos poseen gran potencial para la biorrecuperación del agua del puerto de Isla de Toas, contaminada con hidrocarburos del petróleo, por lo cual se recomienda continuar investigando sobre esta tecnología de tratamiento.

Bacterial community dynamic associated with autochthonous bioaugmentation for enhanced Cu phytoremediation of salt-marsh sediments

Autochthonous bioaugmentation for metal phytoremediation is still little explored, particularly its application to estuarine salt marshes, but results obtained so far are promising. Nevertheless, understanding the behaviour of the microbial communities in the process of bioaugmentation and their role in improving metal phytoremediation is very important to fully validate the application of this biological technology. This study aimed to characterize the bacterial community dynamic associated with the application of autochthonous bioaugmentation in an experimentation which showed that Phragmites australis rhizosphere microorganisms could increase this salt marsh plant potential to phytoremediate Cu contaminated sediments. Bacterial communities present in the autochthonous microbial consortium resistant to Cu added to the medium and in the sediment at the beginning and at the end of the experiment were characterized by ARISA. Complementarily, the consortium and the sediment used for its production were characterized by next generation sequencing using the pyrosequencing platform 454. The microbial consortium resistant to Cu obtained from non-vegetated sediment was dominated by the genus Lactococcus (46%), Raoultella (25%), Bacillus (12%) and Acinetobacter (11%), whereas the one obtained form rhizosediment was dominated by the genus Gluconacetobacter (77%), Bacillus (17%) and Dyella (3%). Results clearly showed that, after two months of experiment, Cu caused a shift in the bacterial community structure of sediments, an effect that was observed either with or without addition of the metal resistant microbial consortium. Therefore, bioaugmentation application improved the process of phytoremediation (metal translocation by the plant was increased) without inducing long term changes in the bacterial community structure of the sediments. So, phytoremediation combined with autochthonous bioaugmentation can be a suitable technology for the recovery of estuarine areas, contributing for an efficient risk management strategy of these coastal zones.

Microbial Production of Schwertmannite: Development from Microbial Fundamentals to Marketable Products

Pumped groundwater in the lignite open-cast mines in Lusatia, Germany, contains a high level of ferrous iron (up to 1000 mg/L) at an initial pH of about 5. In recent R&D projects G.E.O.S. developed an innovative water treatment process for ferrous iron oxidation using the autochthonous microbial consortium in the mine water. The pilot plant is operated in the Nochten open-pit mine in cooperation with the LEAG and produces 5 – 10 t of schwertmannite per year. Extensive research work was carried out in parallel to utilize the produced schwertmannite. Pigment production proved to be technically feasible but difficult due to economic and market constraints. However, the high affinity of schwertmannite to oxy-anions provides the suitability for utilization as adsorbent to remove arsenate, antimonate, chromate, molybdate, vanadate or phosphate from mine water or industrial effluents. In the R&D project SURFTRAPII two kinds of filter-stable sorption materials were developed 1) by compacting schwertmannite or 2) by adhesive curing using an organic polymer, respectively. The produced filter-stable adsorbents were tested under technical conditions in cooperation with potential end users to remove arsenate, molybdate and phosphate from mine and industrial water and to concentrate valuable metals. The results showed a better performance of the material compared to other commercially available iron hydroxide adsorbents.

Copper effect in petroleum hydrocarbons biodegradation by microorganisms associated to Juncus maritimus: role of autochthonous bioaugmentation

The bioremediation potential of microorganisms from a saltmarsh plant rhizosphere and application of bioaugmentation in estuarine sediment co-contaminated were investigated. Rhizosediment (sediment in contact with plant roots) of Juncus maritimus was contaminated with copper and/or petroleum, inoculated with different autochthonous microbial consortia (resistant to copper and/or with petroleum degraders) and put in vessels to which plants were transplanted. Vessels were irrigated through a system that simulated estuarine tides. After 5 months, vessels were dismantled and copper and petroleum content in rhizosediments were determined. Copper’s presence reduced the potential of the microorganisms associated to J. maritimus rhizosphere for bioremediation of petroleum hydrocarbons in co-contaminated sediment. Indeed, hydrocarbons removal decreased from 39 to 25% when copper was present. In addition, bioaugmentation was not effective to overcome metal negative effects on petroleum hydrocarbons degradation, and the same removal rate was being observed (ca. 25%). Different methodologies for the formulation of consortia must be tested in this situation of co-contamination. Obtained results should be taken in consideration when planning the recovery of moderately impacted estuaries, aiming an effective protection and management of these areas, in the case of co-contamination.

Effect of petroleum hydrocarbons in copper phytoremediation by a salt marsh plant (Juncus maritimus) and the role of autochthonous bioaugmentation

This work aimed to investigate, under controlled but environmental relevant conditions, the effects of the presence of both inorganic and organic contaminants (copper and petroleum hydrocarbons) on phytoremediation potential of the salt marsh plant Juncus maritimus. Moreover, bioaugmentation, with an autochthonous microbial consortium (AMC) resistant to Cu, was tested, aiming an increase in the remediation potential of this plant in the presence of a co-contamination. Salt marsh plants with sediment attached to their roots were collected, placed in vessels, and kept in greenhouses, under tidal simulation. Sediments were contaminated with Cu and petroleum, and the AMC was added to half of the vessels. After 5months, plants accumulated significant amounts of Cu but only in belowground structures. The amount of Cu was even higher in the presence of petroleum. AMC addition increased Cu accumulation in belowground tissues, despite decreasing Cu bioavailability, promoting J. maritimus phytostabilization potential. Therefore, J. maritimus has potential to phytoremediate co-contaminated sediments, and autochthonous bioaugmentation can be a valuable strategy for the recovery and management of moderately impacted estuaries. This approach can contribute for a sustainable use of the environmental resources. Graphical abstract ᅟ.

A strategy to potentiate Cd phytoremediation by saltmarsh plants – Autochthonous bioaugmentation

The recovery of estuarine environments is in need. Phytoremediation could be a valid option to reduce pollution while preserving natural biodiversity. In this work, estuarine sediments colonized by Juncus maritimus or Phragmites australis were spiked with cadmium in the absence and in the presence of an autochthonous microbial consortium resistant to the metal. The aim of this study was to increase the potential for cadmium phytoremediation that these two halophyte plants have shown. Experiments were carried out in greenhouses with an automatic irrigation system that simulated estuarine tidal cycles. After 2 months, Cd concentration in P. australis stems increased up to 7 times when the rhizosphere was inoculated with the microbial consortium. So, P. australis phytoextraction potential was increased through autochthonous bioaugmentation. As for J. maritimus, up to 48% more Cd (total amount) was observed in its belowground tissues after being subjected to autochthonous bioaugmentation. Therefore, the phytostabilization potential of this plant was promoted. For both plants this increase in cadmium uptake did not cause significant signs of toxicity. Therefore, the addition of autochthonous microorganisms resistant to cadmium seems to be a valuable strategy to potentiate phytoremediation of this metal in saltmarshes, being useful for the recovery of moderately impacted estuaries. This will contribute for an effective management of these areas. Research on this topic regarding estuarine ecosystems, especially saltmarshes, is, to our knowledge, inexistent.

Characterization of the bottom sediments contaminated with polychlorinated biphenyls: Evaluation of ecotoxicity and biodegradability

At the locality of the former producer of PCBs Chemko Strážske in East Slovakia, a large amount of PCBs (the commercial mixture DELOR 103, an equivalent of AROCLOR 1242) is still persisting in sediments and negatively influences health of the population. The objective of this work was to provide a study of ecotoxicity and genotoxicity of PCBs in contaminated sediments. Toxicity of the PCB-contaminated sediments sampled from Zemplínska šírava and Strážsky canal (surroundings of the former producer of PCBs) was determined applying a standard aquatic plant toxicity test using Lemna minor. The endpoints for the test were frond numbers and frond areas. The sediment sampled from Zemplínska šírava was more toxic to L. minor than the one sampled from Strážsky canal. The results on genotoxicity showed that both sediments were not mutagenic toward the standard strains of the Ames test, Salmonella typhimurium TA98 and TA100. This work deals also with biodegradation of PCBs in two samples of the above mentioned contaminated sediments: a) in the natural sediments by autochthonous microbial consortium and b) in the bioaugmented sediments inoculated by allochthonous bacterial strains, two bacterial isolates from long-term PCB-contaminated soil Pseudomonas stutzeri and Alcaligenes xylosoxidans. Both approaches were applied under the biostimulation conditions, with addition of glucose or biphenyl as co-substrates, as well. The highest PCB degradation was observed in the bioaugmented sediment inoculated with bacterial strain P. stutzeri. Addition of biphenyl, as the co-substrate and the inducer, positively affected degradation of PCBs. The bphA1 gene, encoding enzyme biphenyldioxygenase, responsible for the start of PCB degradation, was identified in genome of P. stutzeri, a potential PCB-degrader isolated from long-term PCB-contaminated soil, but not in genome of A. xylosoxidans.

Transformation of a petroleum pollutant during soil bioremediation experiments

The experiment of ex situ soil bioremediation was performed at the locality of the Oil Refinery in Pancevo (alluvial formation of the Danube River, Serbia) polluted with an oil type pollutant. The experiments of biostimulation, bioventilation and reinoculation of an autochthonous microbial consortium were performed during the six-month period (May-November 2006). The changes in the quantity and composition of the pollutant, or the bioremediation effect, were monitored by analysis of the samples of the polluted soil taken in time spans of two weeks. In this way, from the beginning until the end of the experiment, 12 samples were collected and marked as P1-P12 (Pancevo 1-Pancevo 12). The results obtained showed that more significant changes in the composition of the oil pollutant occurred only during the last phases of the experiment (P8-P12). The activity of microorganisms was reflected in the increase of the quantity of polar oil fractions, mainly fatty acid fractions. In this way, the quantity of total eluate increased, and the quantity of the insoluble residue was reduced to a minimum, whereby the oil pollutant was transformed to a form that could be removed more efficiently and more completely from the soil, as a segment of the environment.