Application of an immobilized microbial consortium for the treatment of pharmaceutical wastewater: Batch-wise and continuous studies

In the present investigation,a microbial consortium consisting of four bacterial strains was selected for the treatment of pharmaceutical industry wa stewater.The consortium was immobilized on a natural support matrixLuffa and used for the treatment of real-time pharmaceutical wastewater in batch and continuous processes.The batch process was carried out to optimize the culture conditions and monitor the enzymatic activity.An array of enzymes such as alcohol dehydrogenase,aldehyde dehydrogenase,monooxygenase,catechol 2,3-dioxygenase and hydroquinol 1,2-dioxygenase were produced by the consortium.The kinetics of the degradation in the batch process was analyzed and it was noted to be a first-order reaction.For the continuous study,an aerobic fixed-film bioreactor(AFFBR) was utilized for a period of 61 days with variable hydraulic retention time(HRT) and organic loading rate(OLR).The immobilized microbes treated the wastewater by reducing the COD,phenolic contaminants and suspended solids.The OLR ranged between(0.56±0.05) kg COD·m^(-3) d^(-1) to 3.35 kg COD·m^(-3)·d^(-1) and the system achieved an average reduction of 96.8% of COD,92.6% of phenolic compounds and 95.2% of suspended solids.Kinetics of the continuous process was interpreted by three different models,where the modified Stover Kincannon model and the Grau second-order model proved to be best fit for the degradation reaction with the constant for saturation value,k_(L) being 95.12 g·L^(-1)·d^(-1).the constant for maximum utilization of the substrate U_(max) being 90.01 g·L^(-1) d^(-1) and substrate removal constant KY was1.074 d^(-1) for both the models.GC-MS analysis confirmed that most of the organic contaminants were degraded into innocuous metabolite s.

Kinetics and characteristics of phenanthrene degradation by a microbial consortium

The kinetics and characteristics of phenanthrene degradation by a microbial consortium W4 isolated from Henan Oilfield were investigated. The degradation percentage of solid phenanthrene at 200 mg/L in liquid medium after 6 days of incubation was higher than 95% under the condition of 37 ℃ and 120 r/min by this microbial consortium. The degradation of phenanthrene could be fitted to a first-order kinetic model with the half-life of 1.25 days. The optimum conditions for degradation ofphenanthrene by consortium W4 were as follows： temperature about 37℃, pH from 6.0 to 7.0 and salinity about 8.0 g/L. It was concluded that microbial consortium W4 might degrade phenanthrene via both salicylic acid and o-phthalic acid pathways by analyzing products with GC-MS.

Screening of a microbial consortium with efficient corn stover degradation ability at low temperature

To speed up the degradation of corn stover directly returned to soil at low temperature, the corn stover-degrading microbial consortium GF-20, acclimated to biological decomposition in the frigid region, was successfully constructed under a long-term limiting substrate. To evaluate its potential in accelerating the decomposition of un-pretreated corn stover, the decomposing property, fermentation dynamic and the microbial diversity were analyzed. GF-20 degraded corn stover by 32% after 15-day fermentation at 10℃. Peak activities of filter paperlyase（FPA）, β-glucosidases（CB）, endoglucanases（Cx）, and cellobiohydrolases（C1） were 1.15, 1.67, 1.73, and 1.42 U m L^–1, appearing at the 6th, 3rd, 11 th, and 9th d, respectively. The p H averaged at 6.73–8.42, and the optical density（OD） value peaked at 1.87 at the 120 h of the degradation process. Cellulase, hemicellulase and lignin in corn stover were persistently degraded by 44.85, 43.85 and 25.29% at the end of incubation. Result of denaturing gradient gel electrophoresis（DGGE） profiles demonstrated that GF-20 had a stable component structure under switching the temperature and p H. The composition of the GF-20 was also analyzed by constructing bacterial 16 S r DNA clone library and fungal 18 Sr DNA-PCR-DGGE. Twenty-two bacterial clones and four fungal bands were detected and identified dominant bacteria represented by Cellvibrio mixtus subsp., Azospira oryzae, Arcobacter defluyii, and Clostridium populeti and the fungi were mainly identified as related to Trichosporon sp.

Study of a plugging microbial consortium using crude oil as sole carbon source

A microbial consortium named Y4 capable of producing biopolymers was isolated from petroleum-contaminated soil in the Dagang Oilfield, China. It includes four bacterial strains： Y4-1 （Paenibacillus sp.）, Y4-2 （Actinomadura sp.）, Y4-3 （Uncultured bacterium clone） and Y4-4 （Brevibacillus sp.）. The optimal conditions for the growth of the consortium Y4 were as follows： temperature about 46 ℃, pH about 7.0 and salinity about 20.0 g/L. The major metabolites were analyzed with gas chromatographymass spectrometry （GC-MS）. A comparison was made between individual strains and the microbial consortium for biopolymer production in different treatment processes. The experimental results showed that the microbial consortium Y4 could produce more biopolymers than individual strains, and the reason might be attributed to the synergetic action of strains. The biopolymers were observed with optical and electron microscopes and analyzed by paper chromatography. It was found that the biopolymers produced by the microbial consortium Y4 were insoluble in water and were of reticular structure, and it was concluded that the biopolymers were cellulose. Through a series of simulation experiments with sand cores, it was found that the microbial consortium Y4 could reduce the permeability of reservoir beds, and improve the efficiency of water flooding by growing biomass and producing biopolymers. The oil recovery was enhanced by 3.5% on average. The results indicated that the consortium Y4 could be used in microbial enhanced oil recovery and play an important role in bioremediation of oil polluted environments.

Development and characterization of a functional microbial consortium for crude oil degradation

Crude oil-degrading microbial consortia were enriched from three oil-contaminated sites to achieve the efficient biodegradation of crude oil,especially its refractory residues.The gravimetric method was used to analyze the degradation efficiency of the enriched consortia and changes in the fractions of the crude oil.The effects of changes in environmental factors were also studied to determine the optimal oil-reducing conditions and assess the dominant bacteria of the mixed flora.Results show that all three consortia exhibit reliable crude oil-biodegradation abilities and that their mixture results in biodegradation rate are as high as(48.0±3.5)%over 30 d of incubation.The consortium mixture can degrade 11.1%of the refractory resins,79.7%of the saturated hydrocarbons,and 45.7%of the aromatics in crude oil.Neutral pH,an incubation temperature of 30℃,and low mineral salt concentrations(0.8%to 4.0%)are optimal for crude oil biodegradation.The dominant genera in the consortium mixture include Pseudomonas,Stenotrophomonas,Brucella,Serratia,Brevundimonas,and Achromobacter.The richness and diversity of the microbial community in the consortium remain stable during crude oil degradation.Therefore,microbial enrichment from multiple sources may be performed to construct a mixed consortium for crude oil pollution bioremediation.

Stability Analysis of a Lignocellulose Degrading Microbial Consortium

An active mesophilic lignocellulose degrading microbial consortium, designated LZF-12, was bred from humus-rich soil by successive subcultivation under facultative aerobic static condition. Batch experiments were performed to investigate the structural and functional stability of lignocellulose degradation of rice straw of 10 g · L-1. The results showed that efficient degradation of rice straw(>70%) could be achieved and acetic acid concentration accounted for over 70% of total aqueous products from different generations by microbial consortium LZF-12 within 7 days. Denaturing gradient gel electrophoresis(DGGE) and sequencing of 16 S r DNA sequences amplified from the total consortium DNA representing the presence of sequences were related to those of Clostridium, Clostridium cellulolyticum, Pseudomonas, Acetivibrio and some uncultured bacteria in LZF-12. DGGE pattern profiles from different LZF-12 generations were reproducible, suggesting the relative stabilities of the microbial community structure and succession mechanism in the established consortium.

Co-metabolic and biochar-promoted biodegradation of mixed PAHs by highly efficient microbial consortium QY1

Polycyclic aromatic hydrocarbons(PAHs), typical representatives of the persistent organic pollutants(POPs), have become ubiquitous in the environment.In this study, a novel microbial consortium QY1 that performed outstanding PAHs-degrading capacity has been enriched.The degradation characteristics of single and mixed PAHs treated with QY1 were studied, and the effect of biochar on biodegradation of mixed PAHs and the potential of biochar in PAHs-heavy metal combined pollution bioremediation were also investigated.Results showed that, in single substrate system, QY1 degraded 94.5% of 500 mg/L phenanthrene(PHE) and 17.8% of 10 mg/L pyrene(PYR) after 7 days, while in PHE-PYR mixture system, the biodegradation efficiencies of PHE(500 mg/L) and PYR(10 mg/L) reached 94.0%and 96.2%, respectively, since PHE served as co-metabolic substrate to have significantly improved PYR biodegradation.Notably, with the cooperation of biochar, the biodegradations of PHE and PYR were greatly accelerated.Further, biochar could reduce the adverse impact of heavy metals(Cd^(2+), Cu^(2+), Cr_(2)O_(7)^(2-)) on PYR biodegradation remarkably.The sequencing analysis revealed that Methylobacterium, Burkholderia and Stenotrophomonas were the dominant genera of QY1 in almost all treatments, indicating that these genera might play key roles in PAHs biodegradation.Overall, this study provided new insights into the efficient bioremediation of PAHs-contaminated site.

Optimization of fermentation factors to enhance rice straw degradation ability using a microbial consortium LZF-12

Biological pretreatment has broad application prospects in agricultural waste treatment because of its economic benefits,environmental protection and energy saving characteristics.In this study,a microbial consortium LZF-12 was applied for a biological pretreatment to degrade rice straw.Batch experiments were performed under hydrolysis conditions by using the method of Box-Behnken factorial design(BBD).The results showed that the model multiple correlation coefficient R2 was 0.9816,and the effects of three factors on the degradation of rice straw of LZF-12 as descending order were the initial rice content,chicken manure content,and initial pH value.The interaction between straw concentration,chicken manure concentration,and initial pH value had significant effects on the degradation of a microbial consortium.Under the optimum conditions of 0.86%rice straw,0.5%chicken manure and the initial pH value of 7.0,the degradation rate of rice straw reached 72.4%.There is only a small difference of 0.55%between the experimental value and predicted value from BBD model.Therefore,it is feasible for the established model due to the consistent results between the prediction and experimental value.The microbial consortium LZF-12 has high cellulase enzyme activities and degradation ability over a wide range of temperature and pH value,indicating that it has a good development potential and application prospects in waste biodegradation and biomass energy production.

Exploration of the key functional proteins from an efficient cellulolytic microbial consortium using dilution-to-extinction approach

In the present study, the cellulose binding proteins（CBPs） secreted by a putative cellulolytic microbial consortium were isolated and purified by affinity digestion. The purified CBPs were subsequently separated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis（SDS-PAGE）. Using mass spectrometric analyses, eight CBPs were identified and annotated to be similar to known proteins secreted by Clostridium clariflavum DSM 19732 and Paenibacillus sp. W-61. In addition, in combination with dilution-to-extinction approach and zymogram analysis technique, CBPs 6（97 k Da） and 12（52 k Da） were confirmed to be the key functional proteins that influence cellulolytic activities. Moreover, structural domain analyses and enzymatic activity detection indicated that CBPs 6 and 12 contained glycoside hydrolase families（GH） 9 and 48 catalytic modules, which both revealed endoglucandase and xylanase activities. It was suggested that the coexistence of GH9 and GH48 catalytic domains present in these two proteins could synergistically promote the efficient degradation of cellulose.

Design, analysis and application of synthetic microbial consortia

The rapid development of synthetic biology has conferred almost perfect modification on single cells,and provided methodological support for synthesizing microbial consortia,which have a much wider application potential than synthetic single cells.Co-cultivating multiple cell populations with rational strategies based on interacting relationships within natural microbial consortia provides theoretical as well as experimental support for the successful obtaining of synthetic microbial consortia,promoting it into extensive research on both industrial applications in plenty of areas and also better understanding of natural microbial consortia.According to their composition complexity,synthetic microbial consortia are summarized in three aspects in this reviewand are discussed in principles of design and construction,insights and methods for analysis,and applications in energy,healthcare,etc.

Determination of growth kinetics of microorganisms linked with 1,4-dioxane degradation in a consortium based on two improved methods

The conventional method for determining growth kinetics of microbial consortia relies on the total biomass concentration.This may be inaccurate for substrates that are uncommon in nature and can only be degraded by a small portion of the microbial community.1,4-dioxane,an emerging contaminant,is an example of such substrates.In this work,we evaluated an improved method for determining the growth kinetics of a 1,4-dioxane-degrading microbial consortium.In the improved method,we considered only bacterial taxa whose concentration increase correlated to 1,4-dioxane concentration decrease in duplicate microcosm tests.Using PEST(Parameter Estimation),a modelindependent parameter estimator,the kinetic constants were estimated by fitting the Monod kineticsbased simulation results to the experimental data that consisted of the concentrations of 1,4-dioxane and the considered bacterial taxa.The estimated kinetic constants were evaluated by comparing the simulation results with experimental results from another set of microcosm tests.The evaluation was quantified by the sum of squared relative residual,which was four orders of magnitude lower for the improved method than the conventional method.By further dividing the considered bacterial taxa into oligotrophs and copiotrophs,the sum of squared relative residual further decreased.

Substrate availability and toxicity shape the structure of microbial communities engaged in metabolic division of labor

Metabolic division of labor(MDOL)represents a widespread natural phenomenon,whereby a complex metabolic pathway is shared between different strains within a community in a mutually beneficial manner.However,little is known about how the composition of such a microbial community is regulated.We hypothesized that when degradation of an organic compound is carried out via MDOL,the concentration and toxicity of the substrate modulate the benefit allocation between the two microbial populations,thus affecting the structure of this community.We tested this hypothesis by combining modeling with experiments using a synthetic consortium.Our modeling analysis suggests that the proportion of the population executing the first metabolic step can be simply estimated by Monod-like formulas governed by substrate concentration and toxicity.Our model and the proposed formula were able to quantitatively predict the structure of our synthetic consortium.Further analysis demonstrates that our rule is also applicable in estimating community structures in spatially structured environments.Together,our work clearly demonstrates that the structure of MDOL communities can be quantitatively predicted using available information on environmental factors,thus providing novel insights into how to manage artificial microbial systems for the wide application of the bioindustry.