Microbes-assisted phytoremediation of lead and petroleum hydrocarbons contaminated water by water hyacinth

Abstract An experiment was carried out to explore the impact of petroleum hydrocarbons (PHs)-degrading microbial consortium (MC) on phytoremediation ability and growth of water hyacinth (WH) plants in water contaminated with lead (Pb) and PHs. Buckets (12-L capacity) were filled with water and WH plants, PHs (2,400 mg L−1) and Pb (10 mg L−1) in respective buckets. Plants were harvested after 30 days of transplanting and results showed that PHs and Pb substantially reduced the agronomic (up to 62%) and physiological (up to 49%) attributes of WH plants. However, the application of MC resulted in a substantial increase in growth (38%) and physiology (22%) of WH plants over uninoculated contaminated control. The WH + MC were able to accumulate 93% Pb and degrade/accumulate 72% of PHs as compared to initial concentration. Furthermore, combined use of WH plants and MC in co-contamination of PHs and Pb, reduced Pb and PHs contents in water by 74% and 68%, respectively, than that of initially applied concentration. Our findings suggest that the WH in combination with PHs-degrading MC could be a suitable nature-based water remediation technology for organic and inorganic contaminants and in future it can be used for decontamination of mix pollutants from water bodies. Novelty statement Phytoremediation by aquatic macrophytes is a promising technique for the cleanup of environmental toxins from wastewater. To our knowledge, this is the first study reporting the integrated use of water hyacinth (WH) plants and a newly developed multi-trait microbial consortium for the simultaneous remediation of organic (i.e., petroleum hydrocarbons) and inorganic (i.e., lead) pollutants from the contaminated water. Findings of this study provide the basic but important information on the combined use of WH and microbes for remediation of mix pollution from water bodies. Graphical Abstract Highlights Water hyacinth (WH) successfully remediated lead (Pb) and petroleum hydrocarbons (PHs) from water. Bacterial consortium addition enhanced PHs and Pb removal by WH from water. Application of bacterial culture reduced Pb and PHs phytotoxicity to WH.


Introduction
Wastewater treatment is a hot issue now-a-days in the world due to the overuse of groundwater in agricultural, domestic, and industrial sectors (Zaryab et al. 2017).The wastewater may contain petroleum hydrocarbons (PHs), pesticides, dyes, and heavy metals (HMs) such as lead (Pb), cadmium (Cd), and arsenic (As).The extent of contamination depends on the sources of contamination (He et al. 2019;Chaurasia et al. 2023).These pollutants deteriorate the physicochemical properties of water (i.e., ground and surface) and soil and they are also injurious to living beings, even at relatively lower concentrations (Khalid et al. 2017;Kumar et al. 2023).A report published by the World Bank describes that around 18 million people globally will face severe water scarcity (<1,000 m 3 per capita per year) by 2050 (Kumar 2019).Therefore, it is dire need of time to minimize our dependence on freshwater resources and reuse the wastewater (after a proper treatment) for agriculture to overcome the issues related to water scarcity and water pollution (Ungureanu et al. 2020).
There are various conventional methods used for the treatment of wastewater (Tripathi and Ranjan 2015); however, these techniques are expensive and sometimes produce harmful by-products that are even more persistent and/or eco-toxic than their parent compounds (Khalid et al. 2017;Parra-Arroyo et al. 2022).Therefore, being eco-friendly and economical, the use of biological means (such as bioremediation and phytoremediation) could be appropriate to combat wastewater pollution (Awa and Hadibarata 2020;Parra-Arroyo et al. 2022).In phytoremediation, different mechanisms including phytoaccumulation, phytostabilization, and phytovolatilization can occur.The plant roots release different organic compounds that are similar to PHs, these root exudates attract the microbial communities to degrade major fractions of the organic pollutants in the soil as well as in plants (Feng et al. 2017).Whereas the inorganic contaminants are sorbed by plants through phytoaccumulation and transferred to body tissues where they can be stabilized (Abdel-Shafy and Mansour 2016;Ossai et al. 2020).
The cost-effective and sustainable solution for wastewater treatment is to use aquatic floating plants in natural or artificial wetlands (Stefanakis 2019).The most frequently used floating plants for wastewater treatment are water hyacinth (WH) (Eichhornia crassipes), pennywort (Hydrocotyle umbellata), alligator weed (Alternanthera philoxeroides), vetiver grass (Chrysopogon zizanioides), water lettuce (Pistia stratiotes), and common reed (Phragmites australis) (Rezania et al. 2015;Mahfooz et al. 2020;Sunar et al. 2022).These aquatic macrophytes have submerged roots that provide more surface area to sorb the contaminants as well as provide habitats for microbes to degrade the organic pollutants (Shahid et al. 2020).
The WH plants are selected as potential candidates due to higher growth and potential for remediation of a wide range of pollutants from wastewater (Newete et al. 2016;Mishra and Maiti 2017).The WH is a floating weed, with long porous stems (that are filled with air) and submerged hairy roots.The WH plant doubles its population within a few days in excessive nutrients under a wide range of temperatures (Mahfooz et al. 2020;Shahid et al. 2020).In addition, WH plants transpire a higher amount of water into the air and thus could be suitable candidate for treating wastewater containing organic and inorganic pollutants (Saha et al. 2022).
Different researchers explored the potential of phytoremediation assisted by bacteria in the last few years (Mahfooz et al. 2020;Rehman et al. 2021).The greater metabolic capabilities of microbes such as PHs degrading and plant growth promoting abilities, allow them to degrade/uptake the pollutants from wastewater streams and soil (Varjani and Upasani 2017).Several bacterial species, i.e., Bacillus, Pseudomonas, Enterobacter, Alcaligenes, Achromobacter, Sphingobacterium, and Stenotrophomonas have plant growth promoting and hydrocarbons degrading properties that are used in phytoremediation (Hussain et al. 2018;Kour et al. 2021;Ali et al. 2023).In the recent years, several researchers examined the potential of WH plants with single bacterial strains for phytoremediation studies (Anudechakul et al. 2015;Sindhu et al. 2017;Mahfooz et al. 2020).However, limited studies have been carried out to explore the potential of WH with the selected mixed microbial cultures (microbial consortia) for the remediation of mix water pollution (Alvarez et al. 2017).Mixed microbial cultures possess higher enzymatic activities (due to several strains) that degrade complex pollutants in relatively shorter time as compared to single isolates.Moreover in natural environment, a group of microbes could degrade a specific fraction of a pollutant and make the site cultivable (Zhang and Zhang 2022).Thus, the main objective of this study was to examine the microbe-assisted growth and phytoremediation potential of WH plants in water that is artificially contaminated with Pb and PHs.

Collection of materials and preliminary analyses
Plants of Eichhornia crassipes commonly known as WH, having the same size and weight (0.95 ± 0.05 kg), were collected from a domestic wastewater pond of a small town "Thetian" (31 36 0 44.1 00 N, 73 01 0 40.9 00 E) near Chiniot district, Punjab, Pakistan and brought to the research area of the University of Agriculture Faisalabad (UAF).Plants were washed thoroughly and grown in tap water supplemented with nutrition (half-strength Hoagland's solution) for seven days to acclimatize the plants in the new environment.The sources of PHs and Pb were diesel (obtained from a fuel station Total PARCO, Faisalabad, Pakistan) and lead chloride (PbCl 2 ), respectively.

Preparation of microbial consortium
Microbial strains previously isolated from the PHs contaminated site (Ali et al. 2023) were used for the preparation of a microbial consortium (MC).The bacterial strains identified after BLAST analyses and having accession numbers ON714529 (Alcaligenes faecalis strain MH-2), ON714530 (Alcaligenes sp.strain MH-3), ON714531 (Achromobacter denitrificans strain MH-6), and ON714532 (Sphingobacterium spiritivorum strain MH-9) were mixed in the same proportion in the mineral salt medium (following the chemical composition of Suja et al. 2014) and incubated at 25 C at 150 rpm for seven days (Ali et al. 2023).Thereafter, the developed MC with an approximate bacterial count of 10 8 to 10 9 CFU mL À1 was prepared and used in further experimentation.

Experimental design
A pot experiment was carried out in the wire house of the Institute of Soil and Environmental Sciences (ISES), UAF.The experiment was set up by following a completely randomized design (CRD), with three replications and 12 treatments (see Table S1 for detail).A total of 42 buckets with 12-L water carrying capacity [with a dimension of 33 Â 25 Â 25 cm (L Â W Â D)] were selected and filled with 10 L of tap water.The diesel and PbCl 2 were added to the respective buckets to achieve the desired concentrations of PHs (i.e., 2,400 mg L À1 v/v) and Pb (i.e., 10 mg L À1 w/v).Thereafter, the microbial culture was added to the bucket (50 mL culture with 10 8 to 10 9 CFU mL À1 ) of respective treatments.Half-strength Hoagland's nutrient solution was also applied to all treatments on alternate days to fulfill the nutritional requirements of the plants (Zhao et al. 2020).This solution contained a mixture of micro-and macronutrients (see detail in Table S2) (Auchterlonie et al. 2021).After 30 days of the experiment, WH plants were harvested, and different plant attributes were determined, and water analyses were performed following standard procedures as described below.

Basic analyses of water
Tap water used in this study was obtained by pumping the groundwater and various physicochemical properties of water were determined (Table S3).The pH, EC, TSS, SAR, RSC, calcium þ magnesium (Ca 2þ þ Mg 2þ ), sodium (Na þ ), CO 3 2-, HCO 3 2-, Cl -, SO 4 2-, Pb, Cd, and As were determined following the standard procedures (Estefan et al. 2013).The PH contents in water was determined by following the procedures described by Ali, Sattar, et al. (2020) and Ali, Abbas, et al. (2020).The detail methodology of PHs determination was described below.

Physiological and growth attributes of plants
After 20 days of the experiment, the soil plant analysis development (SPAD) values were measured by a SPAD meter (SPAD-502, Konica Minolta, Europe), while photosynthetically active radiation (PAR), fluorescence yield (Ft), electron transport rate (ETR), and photochemical quantum yield (YII) were measured by photosynthetic yield analyzer (MINI-PAM-II) (WALZ Mess-und Regeltechnik, Effeltrich, Germany) (Ali, Sattar, et al. 2020;Kumar et al. 2023).Fresh plant leaves were used to check the membrane stability index (MSI) and relative water contents (RWCs) by following the protocols of Sairam et al. (2002).After harvesting (i.e., 30 days of the experiment), the growth parameters such as root and shoot lengths, and fresh and dry biomasses of WH plants were measured with a meter stick and an electric weight balance, respectively.
However, the number of leaves and stems was counted manually at the time of harvest.

Lead determination in plants and water samples
Plant samples were digested with a di-acid HNO 3 þ HClO 4 (2:1) mixture.To digest, 0.2 g dried and ground plant material and 6 mL concentrated HNO 3 were added to each flask and kept overnight (Estefan et al. 2013).Thereafter, 3 mL HClO 4 was added to the flasks and placed on the hotplate under the fume hood.These samples were heated vigorously until dense white fumes were observed, and the samples become colorless.Then, removed the samples from the hotplate and 3-4 drops of distilled water were added.The digested samples were cooled, and the filtrate was collected (i.e., 50 mL volume) from each flask.For water samples, the filtrate was collected in 50 mL plastic bottles for direct use (El Azhari et al. 2017).The Pb concentration was measured by running the samples in an atomic absorption spectrophotometer (Afzal et al. 2020).

Residual petroleum hydrocarbons determination
The PHs were analyzed from water samples by using a portable hydrocarbon analyzer (PHA-100plus, PetroSense, FCI Environmental, Inc., Dallas, TX) by following the standard methods (Ali, Sattar, et al. 2020).Before using PHA-100plus for analysis, the equipment was preconditioned and calibrated by following the manual of the instrument.A 100 mL of water sample from each PHs added treatment was collected and used further.The TPH analyzer's probe was directly inserted into the jar to take a measurement.After that, the probe was permitted to rest in room air for five minutes prior to the next measurement.The precision and accuracy of readings are ±10% (Saini et al. 2001).

Statistical analysis
The data were collected and analyzed statistically according to a standard procedure by applying ANOVA and the difference between treatments was compared by the least significant difference (LSD) test using Statistix 8.1 software.To check the correlation among different plant attributes under different treatments, principal component analyses were performed on Origin 2022b software.

Impact of microbial consortium on the growth attributes of water hyacinth plants grown in Pb and PHs contaminated water
The current study revealed the significant (p 0.05) phytotoxicity of PHs and Pb to WH plants.A decrease of 51.0% and 36.4% in root fresh weight, 46.7% and 41.2% in root dry weight, 40.4% and 32.3% in shoot fresh weight, 43.6% and 31.8% in shoot dry weight, 36.9% and 25.0% in shoot length, 42.1% and 21.6% in root length were observed in treatments containing PHs and Pb, respectively, as compared to uncontaminated control (Figure 1 and Table 1).Similarly, the number of flowers (60.0% and 50.0%), the number of leaves (54.5% and 39.4%), and the number of stems (43.2% and 27.0%) were also decreased (under PHs and Pb contamination, respectively) over their respective control (Table 1).
However, the treatments containing MC showed an increase of 18.2% in root dry weight, 22.0% in shoot dry weight, 19.3% in shoot length, 24.1% in root length, 28.6% in the number of flowers, 21.4% in the number of leaves, and 11.9% in number of stems when compared it with uncontaminated control (i.e., without PHs and Pb).The application of MC in PHs added treatments showed an increase of 20.7%, 15.7%, 14.6%, 20.3%, 20.0%, 25.0%, and 8.69% in root dry weight, shoot dry weight, shoot length, root length, number of flowers, number of leaves, and number of stems as compared to PHs contaminated control.Similarly, the Pb added   1 and Table 1).Moreover, the combined contamination of PHs and Pb supplemented with MC showed an increase of 33.9% in root fresh weight, 37.7% in root dry weight, 13.6% in shoot fresh weight, 17.8% in shoot dry weight, 18.0% in shoot length, 13.5% in root length, 20.0% in the number of flowers, 23.5% in the number of leaves, and 17.4% in the number of stems when we compared them with respective control treatment (co-contamination of PHs and Pb), respectively.

Impact of microbial consortium on the physiological attributes of water hyacinth plants grown in Pb and PHs contaminated water
The results revealed that the PHs and Pb cause significant toxicity and ultimately reduced the physiological parameters (p 0.05) of WH plants.In the presence of PHs, the Ft, PAR, YII, and ETR values were decreased by 40.3%, 26.5%, 36.3%, and 39.2%, respectively, than that of uncontaminated control.Similarly, under Pb contamination, a decrease of 28.9%, 22.8%, 18.2, and 29.1% was observed in Ft, PAR, YII, and ETR, respectively (Figure 2).Additionally, a decrease of 29.5% and 21.6% in SPAD value, 23.9% and 13.1% in RWC and 40.8% and 33.4% in MSI (Table 1) was observed under the sole contamination of PHs and Pb, respectively, when we compared it with uncontaminated control.
A positive trend was also observed under PHs contaminated treatments supplemented with MC and an increase of up to 17.3% was observed over their respective PHs contaminated control.The Pb applied treatments in addition to MC also revealed an increase of 8.57-22.6% in all the physiological attributes of WH plants than that of Pb contaminated control.Moreover, the application of MC in the treatment containing PHs and Pb together showed a substantial increase of 14.5% in Ft, 19.3% in PAR, 21.9% in YII, 18.5% in ETR, 12.9% in SPAD value, 15.9% in RWC, and 21.6% in MSI over their respective PHs and Pb added control.

Impact of microbial consortium on Pb removal by water hyacinth plants
The minimum Pb concentration in roots and shoots of WH plants was obtained from the uncontaminated control treatment (Figure 3).However, the plants grown in Pb contaminated water accumulated 42.0% of Pb in roots and 30.0% in shoots over their initially applied concentration.Similarly, the application of MC under Pb contamination showed an uptake of 55.5% in roots and 38.0% in shoots as compared to the initially applied concentration.The application of MC in the treatments containing PHs and Pb together showed an uplift of 39.0% and 33.0% in roots and shoots of WH than that of the initially applied Pb concentration (Figure 3A,B).
The water samples obtained after the experiment showed significant (p 0.05) reduction in Pb contents of all Pb-applied treatments.The minimum Pb concentration (i.e., 6.77% of the initially applied concentration) in water was observed in the treatment where MC and WH plants were used together under Pb contamination (Figure 3C).Likewise, all the planted treatments accumulated a higher amount of Pb in their tissues and the residual Pb contents were decreased in water samples.The remaining concentration of Pb that was present in water samples was 23.6%, 37.2% and 19.7% from the treatments (i.e., P þ Pb, P þ PHs þ Pb, and P þ PHs þ Pb þ MC), respectively.In addition, the unplanted treatments showed a substantial amount of Pb in water samples and the maximum Pb concentration of 78.3% (as compared to the initially applied concentration) was observed in Pb applied treatment (without PHs and MC).Similarly, the unplanted treatment containing Pb and amended with MC showed 58.4% Pb content in water samples as compared to the initially applied concentration.Moreover, the unplanted treatment with combined contamination (i.e., PHs and Pb) shows 75.3% remaining contents of Pb.However, this concentration was further reduced to 52.3%, when supplemented with MC, than that of the initially applied Pb contents.

Impact of microbial consortium on PHs removal by water hyacinth plants from water
The current experiment showed that the remaining concentration of PHs in water varies significantly (p 0.05) in different treatments.The maximum PHs concentration in water samples was observed in the treatments where no plants, microbes, and Pb were added (Figure 4).The unplanted treatment applied with MC showed 62.3% PHs degradation in water.Additionally, the unplanted treatment containing PHs and Pb together, and applied with MC expressed 48.6% PH degradation over the initial amount.However, all the planted treatments accumulated/degraded a higher amount of PHs, and the residual contents decrease in water samples.There are 30.6%,82.7%, 37.2%, and 41.0% PHs degradation observed in the treatments such as respectively, over initial PHs contents.After all, the best degradation (i.e., 82.7% as compared to initial concentration) of PHs was observed in planted treatment where MC was applied (with PHs but without Pb) than the initially applied PHs concentration.

Correlation matrix and principal component analyses
In this study, a correlation analysis was performed to check the interaction among different growth and physiological attributes of WH plants (Fig. S1).The results showed a positive correlation between the physiological and growth attributes (i.e., 0.67-0.99).However, a mixed correlation (i.e., À0.07 to 0.25) was observed among the most measured plant attributes for Pb and/or PHs contamination.Moreover, the principal component analyses represent the distribution of various treatments in WH under Pb and PHs stress.The PC1 and PC2 represent 75.4% and 16.7% variation, respectively, and have a cumulative variation of 92.1% (Fig. S2).Overall, a higher difference among all the applied treatments and better visualization of the relationship between different growth attributes of WH was observed.

Discussion
This study demonstrated a significant reduction in the growth and physiology of WH plants when grown under Pb and/or PHs contamination.However, the use of MC strengthened the physiology and improves the growth of WH plants under pollutants stress.In addition to stress alleviation, the MC was able to improve the phytoremediation potential of WH plants for Pb and PHs probably due to the plant growth promoting characteristics of the microbes.

Impact of microbial consortium on the growth attributes of water hyacinth plants
Results from this study are in line with findings of the previous studies reporting the significant phytotoxicity of organic and inorganic contaminants to the plants (Abdel-Shafy and Mansour 2016; Mahfooz et al. 2020).The reduction in plant growth attributes could be due to higher uptake of contaminants that initiate the destructive mechanisms and stop the oxidative reactions in plant body and ultimately leading to the reduction in the plant biomass (Agnihotri et al. 2018;Jyoti et al. 2022).Similarly, the phytotoxic impacts of PHs and Pb on WH plants could be linked with the changes in membrane structure and enzymatic disturbances (in photosynthesis and respiration) that cause substantial reduction in plant growth (Sachdev et al. 2021).This decrease in plant growth especially the root biomass and length are in a direct match with the findings of Prajapati et al. (2023) who also reported reduced plant growth in abiotic stresses indirectly caused by the HMs.Furthermore, the production of organic acids by microbes can lower the pH of the rootzone and enhance the nutrient uptake by plants even under stress conditions (Ting  et al. 2018;Selvaraj and Velvizhi 2021).Our findings on enhanced growth in the presence of microbial cultures support the observations of Asghar et al. (2016) and Ali et al. (2023) who also reported that microbes could trigger plant growth by the production of auxins, siderophores, P-solubilization, and ACC de-aminase enzymes.Microbes also produce hormones such as indole-3-acetic acid, gibberellins, chitinase, and cellulase that improve plant growth and activate the plant defense against pathogens and phytotoxicity of PHs and Pb (Singh et al. 2019;Khatoon et al. 2020).

Impact of microbial consortium on the physiology of water hyacinth plants
Our findings regarding the physiological attributes of WH directly correlate with the findings of Hussain et al. (2019), and Ali et al. (2021) who also reported the adverse effects of PHs on the physiology of Lotus corniculatus, Lolium multiflorum, and Zea mays.The reduction in physiological attributes of WH plants in current study may be due to the pollutants induced stress that inhibits the photosynthetic activity particularly due to the buildup of HMs in chloroplasts and causes subsequent cell injuries (Rezania et al. 2015;Singh et al. 2017).Additionally, the induced PHs and Pb stress can trigger the accumulation of reactive oxygen species (ROS) that leads toward protein oxidation, DNA damage, hormone imbalance, and peroxidation of bio-membranes (Gupta and Seth 2020;Wani et al. 2020).According to Malar et al. (2016), Pb can bind with nucleic acid and cause condensation and aggregation of chromatin.It also inhibits the processes of transcription and replication that ultimately affect the cell divisions (Afzal et al. 2020).The accumulation of PHs and Pb in stomata causes higher transpiration rates, which ultimately clog the stomatal openings and adversely affect plant growth (Nguyen et al. 2021).Similarly, the RWCs of the leaves were lower under contamination, and this might be due to the clogging of stomata that breaks the column of transpiration and causes desiccation in leaves (Ali et al. 2023).A decreased photosynthetic rate could also be attributed to the peroxidation of chloroplast membranes due to higher ROS, H 2 O 2 , and peroxide levels that disturb the photochemical reactions in plants, and the findings are in direct match with the outcomes of Agnihotri and Seth (2020).
However, the use of microbial culture was found to be advantageous in minimizing the phytotoxicity of PHs to WH plants by strengthening the plant's oxidative mechanisms.It has been shown that microbial cultures reduce ethylene production by ACC hydrolysis under stressed conditions (Correa-Garc ıa et al. 2018).The microbes reduce the impacts of PHs and use them as a carbon source by the production of surfactants, emulsifiers, polysaccharides, and other enzymes that help to degrade the hydrocarbons (Shekhar et al. 2015;Ali et al. 2023).Microbes also reduced the production of ROS, H 2 O 2 , and peroxide by strengthening the antioxidative defense system of plants (Ahmad et al. 2021; Chandwani and Amaresan 2022).More importantly, the production of exopolysaccharides, IAA, phosphate solubilization, and siderophore formation activities could further strengthen the plants by boosting their immunity (Ali et al. 2023).It was also observed in our other studies that these microbes reduced the toxicity of contaminants by lowering the production of stress induced enzymes such as superoxide dismutase, peroxidase, and catalase (Ali et al. 2023).

Impact of microbial consortium on phytoremediation of Pb and PHs by water hyacinth plants
The morphological and physiological attributes of the WH plant also play a vital role in remediation or accumulation of HMs (Purnamawati et al. 2020).In this study, it was noticed that the WH plants uptake more Pb in root as compared to upper vegetative parts (Abdel-Sabour 2010; Romanova et al. 2016).The roots of WH contain pHdependent charge sites that accumulate and absorb or adsorb the cations (especially HMs) and minimize the translocation of contaminants to upper parts (Galgali et al. 2023).However, at relatively higher contamination, the roots also deliver a substantial amount of Pb to shoots (Newete et al. 2016;Peng et al. 2020).The plant roots provide more surface area and habitat for microbes to attach and degrade organic pollutants such as PHs (de Lima et al. 2022).The porous and airy stems of WH also accumulate an excessive amount of contaminants to store (Pb) or degrade (PHs) the contaminant in the plant body (Abdel-Shafy and Mansour 2016; Lu 2017).
Several studies on rhizoremediation reported that the use of microbes particularly mixed culture or microbial consortia could be effective (due to higher enzymatic diversity, synergy, and adaptability) in improving plant growth and enhancing the removal of PHs, Pb, and other related compounds from contaminated environments (Hussain et al. 2018;Ali, Abbas, et al. 2020).In the present study, the developed MC was able to remove substantial amounts of PHs and Pb from water.Similarly, in the presence of MC, plants showed higher removal of PHs than that of unplanted treatments, suggesting the presence of plant-beneficial microbes in MC that overall improved the rhizoremediation potential (Abdel-Shafy and Mansour 2016; Ali et al. 2023).Although plants face toxicity when pollutants are above a certain level, but they could also remove a certain amount of organic and inorganic pollutants from the media through various mechanisms (Awa and Hadibarata 2020).Here, in this study, WH plants were able to remediate PHs and Pb from the aqueous media.However, this removal of PHs from the water was further improved in the presence of MC, supporting the findings of the previous studies (Varjani and Upasani 2017;Mahfooz et al. 2020).These improved effects could be due to the presence of beneficial microbes in microbial culture that influence the PHs availability to the plants through many processes including the production of organic acids, the liberation of chelators (chelation), protonation, and chemical transformation (Fenibo et al. 2019).Overall findings of this research indicate that the integrated use of WH plants and microbes could be a suitable option to treat wastewater polluted with organic and inorganic contaminants and make the wastewater suitable for irrigation in agriculture after treatment.Furthermore, the technology developed in this study could be useful in addressing the currently prevailing water scarcity and food security issues.

Conclusions
The WH (Eichhornia crassipes) plants have incredible potential to uptake HMs from contaminated waters.In the presence of contaminants, the roots of WH plants accumulated higher amount of Pb in respect to aerial parts, indicating the rhizofiltration potential of WH plants for HMs.The higher concentration of organic and inorganic contaminants in water decreased the overall growth of WH plants by altering the physiological and enzymatic activities.The application of MC reduced the phytotoxicity of PHs and Pb to WH plants and effectively increased the plant biomass (which is one of the basic indicator characteristics for phytoremediation), Pb uptake by plants and PHs degradation in the water.Our findings suggest that the WH plants in combination with MC could be used for the removal of mixed pollution (organic and inorganic) from the water bodies.In future, this technology could be employed to treat water bodies contaminated with both organic and inorganic pollutants.The treated water could be further used in agriculture to meet the current shortcoming of irrigation water.

Figure 1 .
Figure 1.Effect of a microbial consortium on root fresh (A) and dry (B) weights and shoot fresh (C) and dry (D) weights of water hyacinth grown in PHs and Pb contaminated water.After 30 days of transplantation, fresh and dry weights of the root and shoot were recorded.The standard deviation and means of three replicates are represented by the error bars and columns, respectively, and different small letters on columns represent the extent of significance among different treatments means at p 0.05.P: plant; PHs: petroleum hydrocarbons; Pb: lead; MC: microbial consortium.

Figure 2 .
Figure 2. Effect of a microbial consortium on fluorescence yield (A), photosynthetically active radiation (B), photochemical quantum yield (C), and electron transport rate (D) of water hyacinth grown in PHs and Pb contaminated water.After 20 days of transplantation, the physiological attributes of WH were recorded.The standard deviation and means of three replicates are represented by the error bars and columns, respectively, and different small letters on columns represent the extent of significance among different treatment means at p 0.05.P: plant; PHs: petroleum was were hydrocarbons; Pb: lead; MC: microbial consortium.

Figure 3 .
Figure 3.Effect of a microbial consortium on Pb uptake in roots (A) and shoots (B) of water hyacinth and remaining Pb in water (C).The Pb analyses were done after 30 d of transplanting.The standard deviation and means of three replicates are represented by the error bars and columns, respectively, and different small letters on columns represent the extent of significance among different treatment means at p 0.05.P: plant; PHs: petroleum hydrocarbons; Pb: lead; MC: microbial consortium.

Figure 4 .
Figure 4. Effect of a microbial consortium on PHs removal by water hyacinth from PHs and Pb contaminated water.Petroleum hydrocarbons analyses were done after 30 d of transplanting.The standard deviation and means of three replicates are represented by the error bars and columns, respectively, and different small letters on columns represent the extent of significance among different treatment means at p 0.05.P: plant; PHs: petroleum hydrocarbons; Pb: lead; MC: microbial consortium.

Table 1 .
Effects of a microbial consortium on growth and physiological attributes of water hyacinth grown in PHs and Pb contaminated water.SPAD: soil plant analysis development; RWC: relative water contents; MSI: membrane stability index.The standard deviation and means of three replicates are represented by the error bars and columns, respectively, and different small letters on columns represent the extent of significance among different treatments means at p 0.05.treatments with MC showed 32.8%, 23.2%, 16.9%, 29.5%, 37.5%, 23.1%, and 15.6% increases in root dry weight, shoot dry weight, shoot length, root length, number of flowers, number of leaves, and number of stems as compared to Pb contaminated control (Figure