Bioaugmentation Strategy Research Articles

Unveiling six novel bacterial strains for fipronil and thiobencarb biodegradation: efficacy, metabolic pathways, and bioaugmentation potential in paddy soil

IntroductionSoil bacteria offer a promising approach to bioremediate pesticide contamination in agricultural ecosystems. This study investigated the potential of bacteria isolated from rice paddy soil for bioremediating fipronil and thiobencarb, common agricultural pesticides.MethodsBacterial isolates capable of degrading fipronil and thiobencarb were enriched in a mineral salt medium. A response surface methodology with a Box-Behnken design was utilized to optimize pesticide degradation with the isolated bacteria. Bioaugmentation tests were performed in paddy soils with varying conditions.Results and discussionSix strains, including single isolates and their mixture, efficiently degraded these pesticides at high concentrations (up to 800 µg/mL). Enterobacter sp., Brucella sp. (alone and combined), and a mixture of Stenotrophomonas sp., Bordetella sp., and Citrobacter sp. effectively degraded fipronil and thiobencarb, respectively. Notably, a single Pseudomonas sp. strain degraded a mixture of both pesticides. Optimal degradation conditions were identified as a slightly acidic pH (6-7), moderate pesticide concentrations (20-50 µg/mL), and a specific inoculum size. Bioaugmentation assays in real-world paddy soils (sterile/non-sterile, varying moisture) demonstrated that these bacteria significantly increased degradation rates (up to 14.15-fold for fipronil and 5.13-fold for thiobencarb). The study identifies these novel bacterial strains as promising tools for bioremediation and bioaugmentation strategies to tackle fipronil and thiobencarb contamination in paddy ecosystems.

Bacterial bioaugmentation for paracetamol removal from water and sewage sludge. Genomic approaches to elucidate biodegradation pathway

Wastewater treatment plants (WWTPs) are recognized as significant contributors of paracetamol (APAP) into the environment due to their limited ability to degrade it. This study used a bioaugmentation strategy with Pseudomonas extremaustralis CSW01 and Stutzerimonas stutzeri CSW02 to achieve APAP biodegradation in solution in wide ranges of temperature (10-40oC) and pH (5-9), reaching DT50 values < 1.5hours to degrade 500mgL-1 APAP. Bacterial strains also mineralized APAP in solution (<30%), but when forming consortia with Mycolicibacterium aubagnense HPB1.1, mineralization significantly increased (up to 74% and 58% for CSW01+HPB1.1 and CSW02+HPB1.1, respectively), decreasing DT50 values to only 1 and 9 days. Despite the complete degradation of APAP and its high mineralization, residual toxicity throughout the process was observed. Three APAP metabolites were identified (4-aminophenol, hydroquinone and trans-2-hexenoic acid) that quickly disappeared, but residual toxicity remained, indicating the presence of other non-detected intermediates. CSW01 and CSW02 degraded also 100% APAP (50mgkg-1) adsorbed on sewage sludge, with DT50 values of only 0.7 and 0.3 days, respectively, but < 15% APAP was mineralized. A genome-based analysis of CSW01 and CSW02 revealed that amidases, deaminases, hydroxylases, and dioxygenases enzymes were involved APAP biodegradation, and a possible metabolic pathway was proposed. Environmental ImplicationThe wide use of paracetamol (APAP) involves ecological risks, being considered an emerging pollutant. APAP excreted by humans ends up in WWTPs, where its elimination is not complete, remaining in part in the effluent treated waters (discharged into surface waters used for soil irrigation) and in part adsorbed on sewage sludge (used as fertilizer in agricultural soils). APAP bioremediation in WWTPs is the unique opportunity to remove it from both matrices before its dispersion in the environment.The novelty of this study is the isolation of two bacterial strains from sewage sludge, P. extremaustralis CSW01 and S. stutzeri CSW02, that could degrade very high concentrations of APAP and their main formed metabolites, both in water and, for the first time, in sewage sludge, in very short periods of time, and even reach high percentages of APAP mineralization in water. Moreover, CSW01 and CSW02 were active under wide ranges of temperature and pH, and are therefore excellent candidates for the chance to achieve a reduction of APAP toxicity in the environment. In addition, by a genome-based analysis, enzymes possibly involved in APAP biodegradation have been identified and a possible degradation pathway has been proposed.

Bioaugmentation by enriched hydrogenotrophic methanogens into trickle bed reactors for H2/CO2 conversion

Biomethanation represents a promising approach for biomethane production, with biofilm-based processes like trickle bed reactors (TBRs) being among the most efficient solutions. However, maintaining stable performance can be challenging, and both pure and mixed culture approaches have been applied to address this. In this study, inocula enriched with hydrogenotrophic methanogens were introduced to to TBRs as bioaugmentation strategy to assess their impacts on the process performance and microbial community dynamics. Metagenomic analysis revealed a metagenome-assembled genome belonging to the hydrogenotrophic genus Methanobacterium, which became dominant during enrichment and successfully colonized the TBR biofilm after bioaugmentation. The TBRs achieved a biogas production with > 96 % methane. The bioaugmented reactor consumed additional H2. This may be due to microbial species utilizing CO2 and H2 via various CO2 reduction pathways. Overall, implementing bioaugmentation in TBRs showed potential for establishing targeted species, although challenges remain in managing H2 consumption and optimizing microbial interactions.

The dual role of biochar in boosting phenol biodegradation and anti-inhibition performance against hazardous substrate

Enhancing the biodegradation of hazardous recalcitrant organic compounds from wastewater has garnered increasing attention. Herein, bamboo biochar was screened for subsequent investigation as it considerably enhanced hazardous phenol removal efficiency by 125.68 % over the biochar-free system at 700 mg/L. Besides, the influencing factors were optimized, including biochar dosage and phenol concentration. However, the phenol removal rate decreased by 75.91 % within 15 hours when utilizing biochar oxidized by H2O2, perhaps due to eliminating aromatic clusters on biochar. Combined with FTIR analysis, CO and -OH on aromatic clusters of biochar were recognized as the underlying contributors to facilitating electron transfer in phenol biodegradation. Furthermore, the ortho-disubstituted benzene ring was discovered on biochar, which may originate from catechol, an intermediate during phenol degradation, suggesting that biochar also serves as a site for phenol biodegradation. Moreover, the fabricated biochar-sodium alginate microspheres enhanced anti-inhibition to phenol over suspended bacteria by 192.15 %. The system also eliminated 99.93 % of phenol after the seven recycles at 1258.75 mg/L, exhibiting excellent reusability. This work provides valuable insights into bioaugmentation strategies for bio-degrading phenol using biochar.

Tracking atrazine degradation in soil combining 14C-mineralisation assays and compound-specific isotope analysis

The quantification of pesticide dissipation in agricultural soil is challenging. In this study, we investigated atrazine biodegradation in both liquid and soil experiments bioaugmented with distinct atrazine-degrading bacterial isolates. This was achieved by combining 14C-mineralisation assays and compound-specific isotope analysis of atrazine. In liquid experiments, the three bacterial isolates mineralised over 40% of atrazine, demonstrating their potential for extensive degradation. However, the kinetics of mineralisation and degradation varied among the isolates. Carbon stable isotope fractionation was similar for Pseudomonas isolates ADPT34 and ADP2T0, but slightly higher for Chelatobacter SR27. In soil experiments, atrazine primarily degraded into atrazine-desethyl, while atrazine-hydroxy was mainly observed in experiments with SR27. Atrazine mineralisation in soil by ADPT34 and SR27 exceeded 40%, whereas ADP2T0 exhibited a mineralisation rate of 10%. In experiments with ADPT34 and SR27, atrazine 14C-residues were predominantly found in the non-extractable fraction, whereas they accumulated in the extractable fraction in the experiment with ADP2T0. Compound-specific isotope analysis (CSIA) relies on changes of stable isotope ratios and holds potential to evaluate herbicide transformation in soil. CSIA of atrazine indicated atrazine biodegradation in water and solvent extractable soil fractions and varied between 29% and 52%, depending on the bacterial isolate. Despite atrazine degradation in both soil fractions, a significant portion of atrazine residues persisted, depending on the bacterial degrader, initial cell concentration, and mineralisation and degradation rates. Overall, our approach can aid in quantifying atrazine persistence and degradation in soil, and in optimizing bioaugmentation strategies for remediating soils contaminated with persistent herbicides.

Bioaugmentation protocols involving Methanobrevibacter thaueri and Pecoramyces ruminantium for investigating lignocellulose degradation and methane production from alfalfa stalks

Two protocols involving batch cultures were used to investigate the bioaugmentation of methane production by Pecoramyces ruminantium, and Methanobrevibacter thaueri. Protocol I examined the effect of altering the proportion of the microbial constituents in inoculum on alfalfa stalk fermentations and showed a 25 % improvement in dry matter loss in cultures where the inoculum contained just 30 % of co-culture and 70 % of fungal monoculture. Protocol II involved consecutive cultures and alternating inoculations. This protocol resulted in 17–22 mL/g DM methane production with co-cultures a 30 % increase in methane relative to the fungal monoculture. Both protocols indicate that the co-culture rapidly dominated and was more resilient than the monoculture. Synergistic interaction between fungus and methanogen, promoted more efficient lignocellulose degradation and higher methane yield. This study highlighted the potential of microbial co-cultures for enhancing methane production from lignocellulosic biomass, offering a promising bioaugmentation strategy for improving biogas yields and waste valorization.

How bioaugmentation for pesticide removal influences the microbial community in biologically active sand filters

Removing pesticides from biological drinking water filters is challenging due to the difficulty in activating pesticide-degrading bacteria within the filters. Bioaugmented bacteria can alter the filter's microbiome, affecting its performance either positively or negatively, depending on the bacteria used and their interaction with native microbes. We demonstrate that adding specific bacteria strains can effectively remove recalcitrant pesticides, like metaldehyde, yielding compliance to regulatory standards for an extended period. Our experiments revealed that the Sphingobium CMET-H strain was particularly effective, consistently reducing metaldehyde concentrations to levels within regulatory compliance, significantly outperforming Acinetobacter calcoaceticus E1. This success is attributed to the superior acclimation and distribution of the Sphingobium strain within the filter bed, facilitating more efficient interactions with and degradation of the pesticide, even when present at lower population densities compared to Acinetobacter calcoaceticus E1. Furthermore, our study demonstrates that the addition of pesticide-degrading strains significantly impacts the filter's microbiome at various depths, despite these strains making up less than 1% of the total microbial community. The sequence in which these bacteria are introduced influences the system's ability to degrade pesticides effectively. This research shows the potential of carefully selected and dosed bioaugmented bacteria to improve the pesticide removal capabilities of water filtration systems, while also highlighting the dynamics between bioaugmented and native microbial communities. Further investigation into optimizing bioaugmentation strategies is suggested to enhance the resilience and efficiency of drinking water treatment systems against pesticide contamination.

Design and Implementation of a Biogas Pilot Plant for Bioaugmentation Strategies in a rural municipality

The transition towards renewable energy sources is imperative for achieving sustainability and mitigating climate change impacts. Among various renewable energies, biogas stands out for its dual role in waste management and energy production. This study introduces the design and implementation of a biogas pilot plant aimed at exploring bioaugmentation strategies to enhance biogas yield and quality. The pilot plant, located at Aras de los Olmos, features two independent 3.4m3 digesters, allowing for parallel comparison between standard anaerobic digestion and digestion with microbial enhancements. The plant is equipped with monitoring and control systems for precise regulation of environmental conditions, such as temperature, and for real-time measurement of biogas composition. Some initial experiments using a mix of agricultural wastes demonstrated the plant's capability to adapt to varied feedstock. Despite suboptimal temperature conditions, preliminary results indicated a high methane content, suggesting significant potential for bioaugmentation to improve biogas production efficiency. The study highlights the importance of controlled environmental conditions and introduces a novel bioaugmented digestion approach using selected microbial consortia. This research contributes to the broader goal of enhancing biogas technology's efficiency and sustainability, offering insights into the practical application of bioaugmentation in biogas production.

A sustainable, zero-waste approach for production of biohydrogen from chicken manure slurry by hybrid recycling of digestate

This study provides a sustainable approach to produce biohydrogen through the long-term hydrogenic fermentation of chicken manure (CM) in a semi-continuous stirred tank reactor (CSTR) under different organic loading rates (OLRs). To ensure the zero-waste route and sustainability, the total digestate was mechanically separated into liquid and solid fractions. The solid digestate fraction was thermally treated to produce biochar, while the liquid digestate fraction was biologically treated through bioaugmentation with a novel heterotrophic nitrification-aerobic denitrification (HD-AN (bacterial strain (Alcaligenes sp. ME-1). The results showed that the high concentration of free ammonia nitrogen (FAN) contents of CM could inhibit methanogenesis and induce hydrogen production. The ORLs of 2.5, 3.5, 4.5, and 5.5 gVS/L.d imposed to the CSTR resulted in volumetric hydrogen production (VHP) of 643.3 ± 37, 908.8 ± 64.5, 1077.8 ± 95.17, and 1383.3 ± 156.8 mL/L.d, respectively. The microbial community structures indicated the long-term adaptation of hydrogen-producing bacteria and methanogenesis inhibition. The bioaugmentation process removed 83.3 % of total ammonia and 66.2 % of the chemical oxygen demand (COD) from the liquid digestate fraction. The characteristics of the biochar derived solid digestate is suitable for land applications as fertilizer. The hybrid approach combining biohydrogenation, pyrolysis, and bioaugmentation, maximizes the utilization of chicken manure slurry while conforming to the sustainable development goals.

Simulation of microbial transport and petroleum hydrocarbon compound biodegradation in a fracture–matrix coupled system

In-situ bioremediation technology is considered an ideal and environment-friendly approach for the largescale treatment of petroleum-contaminated soil. Most earlier studies on bioremediation have focused on the biostimulation techniques, which can enhance the biodegradation capabilities of indigenous bacteria, rather than on bioaugmentation involving the introduction of exogenous microorganisms. Additionally, contaminated soil sites typically contain both natural and artificial fractures. These fractures serve as preferential transport pathways, complicating the transport of bacteria and related solutes. This study proposes a mathematical model to simulate the transport of exogenous bacteria and electron acceptors during the degradation of petroleum hydrocarbon pollutants in a fractured aquifer system. The model incorporates the processes such as microbial convection, diffusion, adsorption, chemotaxis, growth, death, and microbial metabolic reactions. Simulation results demonstrate that considering microbial transport significantly affects the prediction of contaminant degradation, particularly with regard to the transport of electron acceptors. The growth rate of bacteria has an evident effect on the efficiency of contaminant remediation, and microbial chemotaxis can significantly enhance the degradation efficiency. The proposed mathematical model serves as a valuable tool for assessing the effectiveness of bioaugmentation strategies and can aid in the design and optimization of remediation efforts for contaminated and fractured aquifers.

Autochthonous bioaugmentation strategies for the successful bioremediation of high-salt petrochemical wastewater using a biosurfactant-producing Enterobacter cloacae Z11

Petrochemical wastewater contains a high concentration of refractory aliphatic and aromatic hydrocarbons. Bioremediation of these hazardous materials using autochthonous bioaugmentation (ABA) strategy is attracting increasing interest. Herein, an indigenous biosurfactant-producing bacteria Z11 was isolated and identified as Enterobacter sp. The reintroduction of Z11 into petrochemical wastewater led to a substantial reduction (P < 0.01) in TPHs, decreasing from 8099 to 1723 mg/L, as well as a significant decrease in COD, decreasing from 8064.2 to 1689.2 mg/L. At a critical micelle concentration of 200 mg/L, the biosurfactant synthesized by Z11 exhibited an extraordinary decrease in surface tension from 67.5 to 29 mN/m. The biosurfactant demonstrated favorable surface activity over a wide pH, temperature, and salinity range. Based on a series of chemical analyses, the biosurfactant was classified as phospholipid. The autochthonous bioaugmentation technique developed by Z11 indicated a significant increase (P < 0.05) in the degradation of n-alkanes of varying chain lengths and polycyclic aromatic hydrocarbons. The analysis of the microbial composition demonstrated that the addition of Z11 caused a rise in bacterial populations capable of hydrocarbon decomposition, such as Pseudomonas sp. and Stenotrophomonas sp. The activities of two enzymes involved in degradation, alkane hydroxylase and alcohol dehydrogenase, increased dramatically and showed a significant (P < 0.05) correlation with Enterobacter sp. Z11. The proposed mechanism could be elucidated that functional genes regulate the secretion of biodegradation enzymes and biosurfactants to promote the deep degradation of petroleum hydrocarbons. This study provides technical support for the reintroduction of autochthonous microorganisms capable of producing biosurfactants in implementing in situ ABA strategies.

Safety attributes of Pseudomonas sp. P26, an environmental microorganism with potential application in contaminated environments

Currently, the selection of non-pathogenic microorganisms that lack clinically relevant antimicrobial resistance is crucial to bioaugmentation strategies. Pseudomonas sp. P26 (P26) is an environmental bacterium of interest due to its ability to remove aromatic compounds from petroleum, but its safety characteristics are still unknown. The study aimed to: a) determine P26 sensitivity to antimicrobials, b) investigate the presence of quinolone and β-lactam resistance genes, c) determine the presence of virulence factors, and d) evaluate the effect of P26 on the viability of Galleria mellonella (an invertebrate animal model). P26 antimicrobial sensitivity was determined in vitro using the Kirby-Bauer agar diffusion method and the VITEK 2 automated system (BioMerieux®). Polymerase Chain Reaction was employed for the investigation of genes associated with quinolone resistance, extended-spectrum β-lactamases, and carbapenemases. Hemolysin and protease production was determined in human blood agar and skimmed-milk agar, respectively. In the in vivo assay, different doses of P26 were injected into Galleria mellonella larvae and their survival was monitored daily. Control larvae injected with Pseudomonas putida KT2440 (a strain considered as safe) and Pseudomonas aeruginosa PA14 (a pathogenic strain) were included. Pseudomonas sp. P26 was susceptible to most evaluated antimicrobials, except for trimethoprim-sulfamethoxazole. No epidemiologically relevant genes associated with quinolone and β-lactam resistance were identified. Hemolysin and protease production was only evidenced in the virulent strain (PA14). Furthermore, the results obtained in the in vivo experiment demonstrated that inocula less than 108 CFU/mL of P26 and P. putida KT2440 did not significantly affect larval survival, whereas larvae injected with the lowest dose of the pathogenic strain P. aeruginosa PA14 experienced instant mortality. The results suggest that Pseudomonas sp. P26 is a safe strain for its application in environmental bioremediation processes. Additional studies will be conducted to ensure the safety of this bacterium against other organisms.

Metagenome reveals the possible mechanism that microbial strains promote methanogenesis during anaerobic digestion of food waste

For better understanding the mechanism of microbial strains promoting methane production, four strains Hungatella xylanolytica A5, Bacillus licheniformis B1, Paraclostridium benzoelyticum C2 and Advenella faeciporci E1 were inoculated into anaerobic digestion systems. After bioaugmentation, the cumulative methane production of A5, B1, C2 and E1 groups elevated by 11.68%, 8.20%, 18.21% and 15.67% compared to CK group, respectively. The metagenomic analysis revealed that the species diversity and uniformity of the experimental groups was improved, and hydrolytic acidifying bacteria, represented by Clostridiaceae, Anaerolineaceae and Oscillospiraceae, and methanogens, such as Methanotrichaceae and Methanobacteriaceae, were enriched. Meanwhile, the abundance of key genes in carbohydrate, pyruvate and methane metabolism was increased in the inoculated groups, providing reasonable reasons for more methane production. The strengthening mechanism of microbial strains in this study offered a theoretical foundation for selecting a suitable bioaugmentation strategy to solve the problems of slow start-up and low methane production in anaerobic digestion.

A bioaugmentation strategy to recover methane production under sulfate-stressed conditions: Highlights on targeted sulfate-reducing bacteria and DIET-related species

Bioaugmentation has been recognized as a key strategy to improve the anaerobic digestion efficiency in organic waste treatment. Methanosarcina barkeri possesses direct interspecies electron transfer capability, a characteristic that allows it to outcompete other unwanted species such as sulfate-reducing bacteria. This study investigated the effects of bioaugmentation with Methanosarcina barkeri DSM800 on two continuous-stirred tank reactors fed with a sulfate-rich feedstock. One of the two reactors was supplemented with magnetite to facilitate direct interspecies electron transfer. Time series quantitative polymerase chain reactions were performed to evaluate the absolute abundance of crucial species, including the augmented Methanosarcina. Results showed increased and stabilized methane production of 22% and 21% in the reactor amended with magnetite and in the control reactor, respectively. Moreover, volatile fatty acids were almost completely consumed in the magnetite-supplemented reactor. The quantitative polymerase chain reaction was used to analyze the abundance of targeted species in response to bioaugmentation. Specifically, Methanosarcina barkeri was not retained in either reactor after one hydraulic retention time. Direct interspecies electron transfer-associated microorganisms showed opposite trends in the two reactors, highlighting the different interactions with Methanosarcina barkeri in the presence and absence of magnetite. Sulfate-reducing bacteria following the dissimilatory sulfate reduction pathway exhibited an opposite behavior in the reactor amended with magnetite, in contrast to those employing the assimilatory sulfate reduction pathway. Overall, the study demonstrated that bioaugmentation with exogenous archaea can considerably alter the microbial community, but the introduced species is not able to establish itself in a stable microbiome. In addition, the strategy could be further tested to control H2S production in real-world waste treatment scenarios. Quantitative polymerase chain reaction proved to be a useful tool for monitoring changes in the absolute abundance of microorganisms in bioreactors, implementing effective monitoring and control strategies to improve overall system performance.

Efficient caproic acid production from lignocellulosic biomass by bio-augmented mixed microorganisms

Producing caproic acid via carboxylate platform is an environmentally-friendly approach for treating lignocellulosic agricultural waste. However, its implementation is still challenged by low product yields and selectivity. A microbiome named cellulolytic acid-producing microbiome (DCB), proficient in producing cellulolytic acid, was successfully acquired and shows promise for producing high-level caproic acid. In this study, a bioaugmentation method utilizing Clostridium kluyveri is proposed to enhance caproic acid yield of DCB using rice straw. With exogenous ethanol, bioaugmentation with Clostridium kluyveri significantly improved the caproic acid concentration and selectivity by 7 times and 4.5 times, achieving 12.9 g/L and 55.1 %, respectively. The addition of Clostridium kluyveri introduced reverse β-oxidation pathway, a more efficient caproic acid production pathway. Meanwhile, bioaugmentation enriched the bacteria proficient in degrading straw and producing short-chain fatty acids, providing more substrates for caproic acid production. This study provides potential bioaugmentation strategies for optimizing caproic acid yield from lignocellulosic biomass.

Bioaugmentation strategies based on bacterial and methanogenic cultures to relieve stress in anaerobic digestion of protein-rich substrates

Anaerobic co-digestion of protein-rich substrates is a prominent strategy for converting valuable feedstocks into methane, but it releases ammonia, which can inhibit the overall process. This study developed a cutting-edge combined culturomic and metagenomic approach to investigate the microbial composition of an ammonia-tolerant biogas plant. Newly-isolated microorganisms were used for bioaugmentation of stressed batch reactors fed with casein, maize silage and their combination. A co-culture enriched with proteolytic bacteria was isolated, selected and compared with the proteolytic collection strain Pseudomonas lundensis DSM6252. The co-culture and P. lundensis were combined with the ammonia-resistant archaeon Methanoculleus bourgensis MS2 to boost process stability. A microbial population pre-adapted to casein was also tested for evaluating the digestion of protein-rich feedstock. The promising results suggest combining proteolytic bacteria and M. bourgensis could exploit microbial co-cultures to improve anaerobic digestion stability and ensure stable productivity even under the harshest of ammonia conditions.

The Stool Microbiome in African Ruminants: A Comparative Metataxonomic Study Suggests Potential for Biogas Production

Lignocellulosic biomass is a promising substrate for anaerobic digestion (AD) in renewable energy generation but presents a significant challenge during the hydrolysis stage of conventional AD due to the recalcitrant nature of this biomass substrate. Rumen fluid is often employed as a bioaugmentation seed to enhance hydrolysis in the AD of lignocellulosic substrates due to its richness in hydrolytic bacteria. However, using rumen fluid to enhance AD processes presents substantial hurdles, including the procurement difficulties associated with rumen fluid and ethical concerns. In this study, the fecal microbiota of 10 African ruminant species from a large zoological park (Bioparc) in Valencia, Spain, were studied using 16S rRNA gene amplicon sequencing. In this study, the fecal microbiota of 10 African ruminant species from a large zoological park (Bioparc) in Valencia, Spain, were studied using 16S rRNA gene amplicon sequencing. The investigation revealed potential similarities between the fecal microbiota from the African ruminants’ and cows’ rumen fluids, as suggested by theoretical considerations. Although direct comparative analysis with cow rumen fluid was not performed in this study, the theoretical framework and existing literature hint at potential similarities. According to our results, the Impala, Blesbok, Dikdik and Bongo ruminant species stood out as having the greatest potential to be used in bioaugmentation strategies. Key genera such as Fibrobacter, Methanobrevibacter, and Methanosphaera in Impala samples suggested Impala rumen fluid’s involvement in cellulose breakdown and methane production. Blesbok and Dikdik exhibited a high abundance of Bacillus and Atopostipes, potentially contributing to lignin degradation. The richness of Prevotellaceae and Rikenellaceae in the Bongo fecal samples is probably associated with structural carbohydrate degradation. Taken together, our results shed light on the microbial ecology of the gut contents of a whole set of Bovidae ruminants and contribute to the potential application of gut microbiota in AD.

Remediation of spent engine oil-contaminated soil through biostimulation and bioaugmentation with sodium dodecyl sulphate (SDS) and indigenous hydrocarbonoclastic bacterial isolates.

Pollution caused by spent engine oil has become a major global ecological concern as it constitutes a big threat to plants, animals, microorganisms and the soil ecosystem. This study was undertaken to examine the remediation of spent engine oil-contaminated soil through biostimulation and bioaugmentation with sodium dodecyl sulphate and indigenous hydrocarbonoclastic bacterial isolates. Twelve mesocosms were organized into four groups designated G1, G2, G3 and G4 and each filled with 2.5kg of soil samples. Each group was composed of three mesocosms to produce a triplicate setup. G1 contained pristine soil which served as a positive control. G2 contained a total petroleum hydrocarbon (TPH) of 913.333mg/kg in the untreated oil-polluted soil which served as a negative control. G3 contained a TPH of 913.333mg/kg in the polluted soil inoculated with indigenous hydrocarbonoclastic bacterial isolates. G4 contained a TPH of 913.333mg/kg in the polluted soil mixed with bacterial consortium and sodium dodecyl sulphate. The level of pollution was 36.5% in the triplicate setup G2, G3 and G4. Fourier Transform Infrared spectroscopy was used to determine the degree of hydrocarbon degradation. The initial TPH value of 913.33mg/kg was reduced by 84.44% (142mg/kg) in soil inoculated with indigenous hydrocarbonoclastic bacterial isolates and by 88.28% (106.66mg/kg) in biostimulated soil. Result of this study show that soil stimulation involving bacterial consortium and sodium dodecyl sulphate was more efficient than bioaugmentation strategy alone used in the remediation of spent engine oil-polluted soil.

Synergistic bioaugmentation with Clostridium thermopalmarium and Caldibacillus thermoamylovorans improved methane production from thermophilic anaerobic digestion of food waste

Microbial bioaugmentation is a promising strategy to increase methane production in thermophilic anaerobic digestion (TAD). In this study, Clostridium thermopalmarium HK1 and Caldibacillus thermoamylovorans QK5 were combined to form a combined microbial inoculant, and the influence of this synergistic bioaugmentation strategy on the TAD of food waste was explored in batch and semi-continuous experiments. The cumulative methane production reached 512.74 ± 8.12 NmL g−1 VS with the addition of the combined microbial inoculant, which was increased by 24.77 % ± 1.98 % compared to the control group, and the bioaugmentation effect was significantly better than that of the group inoculated with C. thermopalmarium HK1 (458.44 ± 4.80 NmL g−1 VS, 11.56 % ± 1.17 %) or C. thermoamylovorans QK5 (478.74 ± 5.73 NmL g−1 VS, 16.50 % ± 1.39 %) individually. The addition of the combined microbial inoculant particularly enriched carbohydrate-degrading bacteria and protein-degrading bacteria. In terms of metabolic functions, bioaugmentation with the combined microbial inoculant enhanced carbohydrate metabolism, amino acid metabolism, and methane metabolism, promoting the complete oxidation of organic matter into CO2 via the tricarboxylic acid cycle (TCA cycle) and driving the conversion of CO2 to methane. In particular, the synergistic effect of C. thermopalmarium HK1 and C. thermoamylovorans QK5 in the combined microbial inoculant resulted in notably increases in the bioaugmentation of carbohydrate and protein degradation, the TCA cycle, and hydrogenotrophic methanogenesis.

Marvels of Bacilli in soil amendment for plant-growth promotion toward sustainable development having futuristic socio-economic implications.

Microorganisms are integral components of ecosystems, exerting profound impacts on various facets of human life. The recent United Nations General Assembly (UNGA) Science Summit emphasized the critical importance of comprehending the microbial world to address global challenges, aligning with the United Nations Sustainable Development Goals (SDGs). In agriculture, microbes are pivotal contributors to food production, sustainable energy, and environmental bioremediation. However, decades of agricultural intensification have boosted crop yields at the expense of soil health and microbial diversity, jeopardizing global food security. To address this issue, a study in West Bengal, India, explored the potential of a novel multi-strain consortium of plant growth promoting (PGP) Bacillus spp. for soil bioaugmentation. These strains were sourced from the soil's native microbial flora, offering a sustainable approach. In this work, a composite inoculum of Bacillus zhangzhouensis MMAM, Bacillus cereus MMAM3), and Bacillus subtilis MMAM2 were introduced into an over-exploited agricultural soil and implications on the improvement of vegetative growth and yield related traits of Gylcine max (L) Meril. plants were evaluated, growing them as model plant, in pot trial condition. The study's findings demonstrated significant improvements in plant growth and soil microbial diversity when using the bacterial consortium in conjunction with vermicompost. Metagenomic analyses revealed increased abundance of many functional genera and metabolic pathways in consortium-inoculated soil, indicating enhanced soil biological health. This innovative bioaugmentation strategy to upgrade the over-used agricultural soil through introduction of residual PGP bacterial members as consortia, presents a promising path forward for sustainable agriculture. The rejuvenated patches of over-used land can be used by the small and marginal farmers for cultivation of resilient crops like soybean. Recognizing the significance of multi-strain PGP bacterial consortia as potential bioinoculants, such technology can bolster food security, enhance agricultural productivity, and mitigate the adverse effects of past agricultural activities.