Antibiofilm and Anti-Quorum Sensing Potential of Safely-Synthesized Hydrated Zirconium Oxide-Coated Alginate Beads against Some Pathogenic Bacteria

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Introduction
Over 780 million people across the globe do not have access to clean and safe water, and an approximate number of about 2.5 billion people in the developing countries do not have adequate sanitation, placing them under a high risk of waterborne diseases [1,2].Waterborne diseases which are caused by various pathogens usually transmitted through water constitutes a major health challenge, resulting in mortalities and morbidities and some of them are directly resulting from deterioration of the environment and pollution [3].Although many eforts are being made to ensure safe water, outbreaks of waterborne infections continue to appear throughout the globe.More than 400 microorganisms cause waterborne diseases and have diferent origins and modes of transmission but more than 95% of these waterborne diseases can be prevented.However, some factors such as lack of resources, emerging resistant pathogens, and chemical contaminants make it difcult [4].Some of the bacteria in water usually evolve into resistant strains that are able to survive the efects of disinfectants, detergents, and antibiotics, making biological treatment of water difcult to achieve except by targeting their quorum sensing network, thus demanding the search for new alternative water treatments.Quorum sensing (QS) involves a cell-cell communication system in bacterial life processes involving secretion, detection, and response to small signalling molecules known as autoinducers (AIs) [5,6].QS controls virulence factors in bacteria such as bioflm formation, violacein production, and motilities [7].Most of the microbial resistance mechanisms and virulence include antibiotic efux pumps, pathogenic gene expression, swarming motility, the production of toxins, and formation of bioflm [8].It is therefore a suitable strategy to search for quorum-quenching materials which can prevent microbial resistance and use them against drug-resistant pathogens [9].However, water is usually contaminated by both biological contaminants and chemical substances.Metal oxides with or without polymers have demonstrated important properties such as antibacterial, adsorption, magnetic properties, large surface area, and surface mobility [10].Such polymer-metal oxide nanocomposites are more potent in water treatment since they possess high photodegradation activity toward pollutants under simulated visible light [10].Polymer nanoparticles are highly used in eliminating pollutants from water because of their tuneable surface chemistry, large surface area, pore size distribution, and perfect mechanical rigidity [11].
Among the metallic materials used in water purifcation, zirconium-based particles are of great interest [14,27,[39][40][41].Te possible rich hydroxyl groups on the zirconium-based particles are responsible for metal removal via ligand or ion exchange [42].Zirconium-based materials are water-insoluble, nontoxic, and stable [43].However, their use alone can cause the release of particles into the water, which can potentially harm native fora and fauna.To solve this, these adsorbents are made into composites with supportive biomaterials.Forming composites of Zr-based particles with supports such as alginate beads [44][45][46], chitosan beads [46][47][48], polystyrene anion exchanger [46,49], and carbon nanotubes has been reported to be highly efective in preventing the release of this adsorbent into the environment [46,50,51].Of these, alginate has a strong afnity for metal ions.Metal ions (positively charged) are electrostatically attracted to negatively charged carboxyl groups in calcium alginate.Te synthesis of various adsorbents made up of alginate beads, cross-linked with calcium ions is usually an environmentally friendly method [28,46,52].Tese composites can be used to remove both cationic and anionic contaminants from wastewater.Generally, hydrothermal [42], precipitation [27], and sol-gel methods [39] are used to synthesize Zr-based composite.Te fltration-steam hydrolysis method is a simple way of coating the polymer with the metal oxides [53].Te morphology and thickness of this coating help in increasing the specifc surface area and also increasing adsorption.It is known that metal alkoxide can be reduced to alcohol (A) and hydrated metal oxide after a fltration-steam hydrolysis reaction.It has been reported that the hydrated zirconium oxide (ZrO(H 2 O)) formed from such a process is composed of many hydrated polymeric species such as ZrAO, HAOAH, and ZrAOH [54,55].
Te adsorption capacities of Zr-based materials have been demonstrated in many studies, especially on the removal of metal ions from wastewater, as described above.Based on our knowledge, there is no study in the literature that determines the antimicrobial properties of zirconium oxide materials especially for waterborne pathogens.Terefore, the aim of the present study is to synthesize hydrated zirconium oxide-alginate beads and determine their efects on virulence factors of some major waterborne pathogens.

Synthesis of Alginate Beads.
Te alginate beads were synthesized by the sol-gel templating method, as described elsewhere [14].Sodium alginate was dissolved in deionized water to prepare alginate solutions with diferent percentages, that is, 1.5 wt % (alginate solution 1) or 2.0 wt % Listeria monocytogenes, and Enterococcus faecalis have been described to infect humans through the consumption of contaminated water or seafood are therefore part of water pathogens [3].Te Gram-negative bacteria involved in this study are Escherichia coli, Pseudomonas aeruginosa, and Salmonella Typhi which have been described as pathogens involved in waterborne diseases [56].Candida species including Candida albicans and Candida tropicalis together with other opportunistic yeasts have been detected in polluted waters [57].Chromobacterium violaceum is an opportunistic Gram-negative bacillus that inhabit soil and water environments especially in tropical and subtropical regions [58].

Evaluation of Percentage Inhibition of Bioflm Using the Crystal Violet Staining Method.
Te antibioflm activity at MIC and sub-MIC concentrations (1, 1/2, 1/4, and 1/8 MIC) of ZAB-1 and ZAB-2 were measured, as described previously [60,61].Briefy, tryptose-soy broth (TSB) containing 0.25% glucose was used and 1% (v/v) overnight microbial cultures were added to 200 μL wells with or without ZAB-1 and ZAB-2 at their MIC and sub-MIC.Te wells with only media and microbial cells served as control.After 48 hours incubation, planktonic bacteria were removed, and the wells were stained with 0.1% crystal violet in distilled water for 10 minutes.After removing the crystal violet, 200 μL of ethanol or 200 μL of 33% glacial acetic acid were flled into the wells, and 125 μL from each well was pipetted into a sterile tube and made up to 1 mL volume with distilled water.Te optical density was read at 550 nm (Termo Scientifc Multiskan FC, Vantaa, Finland), and the percentage inhibition of bioflm calculated as follows: Biofilm inhibition (%) � OD550 Control − OD550 Sample OD550 Control x 100. (1)

Quorum Sensing Inhibition (QSI) Activity of Samples on
C. violaceum CV026.Inhibition of quorum sensing (QS) was performed, as described previously [62,63].Briefy, 100 µL of overnight CV026 culture was added to 5 mL of warm molten soft agar (200 mL H2O, 1.3 g agar, 1.0 g NaCl, 2.0 g tryptone) together with 20 µL of exogenous C6HSL (100 µg/mL) acylhomoserine lactone (AHL).Te mixture was stirred and poured over LBA agar plates as an overlay.5 mm diameter wells were made on the plate surfaces into which 50 µL of sterilized ZAB-1 and ZAB-2 were added, and the plates incubated at 30 °C for 3 days.After this, a creamcoloured halo around each well indicated QSI, and the diameters were recorded in millimetres.Each experiment was done in triplicate.

Violacein Inhibition of Samples of C. violacium CV12472.
ZAB-1 and ZAB-2 were evaluated for qualitative inhibition of violacein pigment to fnd out their QSI potential using C. violaceum ATCC 12472 [64,65].10 µL of C. violaceum overnight cultures, adjusted to 0.4 OD at 600 nm, were added to a 200 µL well containing LB broth in the presence and absence of 20 µL MIC and sub-MICs of samples.C. violaceum ATCC 12472 in LB broth without samples was used as a control.Tese plates were incubated for 24 hours at 30 °C, and the reduction in violacein pigment production was measured through absorbances at 585 nm.Te violacein inhibition percentages were calculated using the following formula: Violacein inhibition (%) � OD 585 control − OD585 sample OD 585 control x100. (2)

Swarming Motility Inhibition in P. aeruginosa PA01.
Swarming motility inhibition was performed, as described elsewhere [66,67].Briefy, P. aeruginosa PA01 overnight cultures were inoculated at the center of swarming plates (0.5% agar, 1% peptone, 0.5% D-glucose, and 0.5% NaCl) containing concentrations of 50, 75, and 100 µg/mL of ZAB-1 and ZAB-2.Te plates without ZAB-1 and ZAB-2 served as controls.Plates were incubated at 37 °C in an upright position for 18 h.Te area covered by bacterial growth or swarming migration fronts was recorded, and the percentage inhibition of the swarming movement was calculated.

Statistical Analysis.
Each experiment was repeated three times, and the results are expressed as means ± standard error of the mean.Te Student's test was used to determine the signifcant diferences between various means, and the values for p < 0.05 were regarded as signifcant.

Characterization of Hydrated Zirconium Oxide-Coated
Alginate Beads.Te encapsulation of hydrated zirconium oxide into the alginate beads was verifed by Fourier transform infrared spectroscopy (FT-IR).Te FT-IR spectra of the raw hydrated zirconium oxide, raw sodium alginate, and hydrated zirconium oxide-coated alginate beads are shown in Figure 2. In the FT-IR of raw hydrated zirconium oxide (Figure 2), the bands with absorption maxima at approximately 1630 cm −1 and 3450 cm −1 were attributed to the bending and stretching vibrations of hydroxyl groups, Notably on the FT-IR, the bending and stretching vibrations of hydroxyl groups linked to the zirconium oxide were at 1630 cm −1 and 3450 cm −1 , and the Zr-OH bending vibration was at approximately 1440 cm −1 [68,69].Hydrated zirconium oxide-coated alginate beads exhibited stretching vibrations of hydroxyl groups smaller than those for sodium alginate since the hydroxyl and carboxylate groups of alginate and the Ca 2+ are chelated [70].SEM analysis was performed to determine the morphology of the alginate bead without hydrated zirconium oxide in comparison with that of hydrated zirconium oxidecoated alginate beads, and SEM photographs are given in Figure 3.In both types of beads, the diference in roughness of the surfaces is clearly visible.In Figure 3, it is clear that after the zirconium oxide coating, the roughness on the surface of the beads increases accordingly and appreciably upon the addition of hydrated zirconium oxide in the surface area of the beads.
Te XRD pattern for the synthesized hydrated zirconiaalginate beads with 2% alginate (ZAB-2) is given in Figure 4. Te intensity and sharpness of the dominant difraction peaks can refect the purity of the synthesized hydrated zirconium oxide-alginate beads.Te signifcant difraction peaks that are comparable to the reported data for monoclinic ZrO 2 suggest high crystallinity as well.Te strongest difraction peak at 28.1 °observed here has been described as the characteristic (111) plane of the monoclinic zirconia phase.Te prominent peak at around 30 °, usually attributed to the characteristic spacing (101) for tetragonal zirconia is absent on the XRD patterns for ZAB-2.Te absence of the most important peak for tetragonal zirconia which occurs at 30 °and corresponds to the spacing (111) for tetragonal zirconia, indicates an almost monoclinic nature.All the observed refection peaks are referable and matched with the JCPDS (01-089-9066) for a dominant monoclinic phase of zirconia.Te characteristic peaks at 2θ angles 28.1, 35.6, 39.8, 45.6, 49.6, 54.2, 55.3, 57.0, 60.2, 68.1, 74.0, and 76.5 have been described as characteristic for the existence of monoclinic phase of ZrO 2 .However, there were some shifts in peak positions at some points, which indicates some changes in the structure due to the added alginate.Te XRD patterns for the ZAB-2 sample indicate a few additional peaks with low intensities which could be ascribable to a trace of the tetragonal phase (340, 350 and 60.20) and calcium alginate (20 °and 28.5 °) matrix.Te peaks at 2θ 34 °, 35 °, and 60.2 °were described as characteristic peaks of the tetragonal phase of zirconia while those at 20.06 °and 28.96 °are known to be calcium alginate peaks.Te most important and majority of peaks in ZAB-2 are comparable to those in a reported study which were attributed to the monoclinic ZrO 2 phase in a sample containing both monoclinic and tetragonal ZrO 2 phases, and it was concluded that the monoclinic phase was greater than the tetragonal phase in terms of content.Summarily, on the XRD patterns of ZAB-2, there was the presence of the major difraction maxima attributable to zirconium dioxide monoclinic phase ascribable to the spacings (111), (002), ( 112), (202), (013), (311), (023), and (114) which are thoroughly described in the literature.Te FT-IR and XRD data were in conformity with the characteristic information reported for ZrO 2 .Te characteristic XRD difraction peak of the monoclinic zirconia phase appeared at 28.1 °and there was an absence of a tetragonal zirconia difraction peak at 30 °, suggesting an almost monoclinic nature [71,72].Other prominent monoclinic zirconia peaks occurred at 2θ angles 28.1, 35.6, 39.8, 45.6, 49.6, 54.2, 55.3, 57.0, 60.2, 68.1, 74.0, and 76.5 in conformity with reported data [73][74][75].Te peaks at 2θ 20.06 °and 28.96 °are attributable to calcium alginate [75,76].Most of the important peaks of ZAB-1 and ZAB-2 are in agreement with those of ZrO 2 with the dominant monoclinic phase [77][78][79].
Biopolymer-metal oxide hybrids such as the ZAB-1 and ZAB-2 synthesized in this study enable chemists to combine the high-tech properties of metal oxides with those of biopolymers and such materials have biological activities including antimicrobial properties [80,81].Tey are usually prepared by dispersing metal oxides into commercially available polymers, as in this study or by incorporating metal oxides during the polymerization process [82].Te encapsulation of the zirconium oxide particles into a natural biopolymer such as alginate makes them more compatible with the environment and living systems and also enables them not to contaminate or leak into the environment while maintaining their properties.Dispersing metal oxides in a biopolymer also improves catalytic, surface, and magnetic properties as well as their weights which facilitates their sedimentation and recovery from the aqueous medium during the water purifcation process [83].Tis means that the synthesized hydrated zirconium oxide-alginate-coated beads (ZAB-1 and ZAB-2) possess suitable properties for wastewater treatment.Tis can be attributed to its absorption properties and antiseptic nature.Te added advantage is that ZAB-1 and ZAB-2 satisfy environmental exigencies due to their biocompatibility and ease of recovery after usage.

Antimicrobial and Antibioflm Activities.
Te antimicrobial activity of the synthesized beads was determined against three Gram-positive bacteria, three Gram-negative bacteria, and two fungi (Table 1).Te MIC values of both ZAB-1 and ZAB-2 were 1.25 mg/mL against E. faecalis and 5 mg/mL against L. monocytogenes.Against S. aureus, the MIC values were 2.5 mg/mL and 1.25 mg/mL for ZAB-1 and ZAB-2, respectively.Te MIC values of ZAB-1 and ZAB-2 were 10 mg/mL against P. aeruginosa and 2.5 mg/mL against S. Typhi.Against E. coli, MIC values were 10 mg/mL and 5 mg/mL for ZAB-1 and ZAB-2, respectively.For the yeast cells, MIC values of ZAB-1 and ZAB-2 were 2.5 mg/mL against C. albicans.Te MIC values of ZAB-1 and ZAB-2 against C. tropicalis were 5 mg/mL and 2.5 mg/mL, respectively.Te antimicrobial activity was almost the same for both beads except against S. aureus, E. coli, and C. tropicalis, against which ZAB-2 was more active than ZAB-1.
Most antimicrobial substances have limited efcacy because they are able to eliminate or inhibit planktonic bacterial communities but are often challenged by bioflm bacterial communities, which are difcult to treat.Bioflms consist of a protective polymeric matrix developed by pathogenic yeasts, Gram-positive and Gram-negative bacteria, and helps them to adapt to environmental stress, antibiotics, starvation, and host immune system [84].Te ability of the synthesized beads (ZAB-1 and ZAB-2) to inhibit bioflms was evaluated at MIC and sub-MIC concentrations and reported in Table 2. ZAB-1 inhibited the bioflm of S. aureus with percentage inhibition varying from 26.47 ± 0.42% at MIC to 04.83 ± 0.11% at MIC/4.Te bioflm inhibition percentage of ZAB-2 against S. aureus varied from 74.22 ± 2.24% at MIC to 08.70 ± 0.63% at MIC/8.Against E. faecalis, bioflm percentage inhibition varied from 14.56 ± 0.13% at MIC to 5.06 ± 0.07% at MIC/2 for ZAB-1 and from 22.91 ± 1.27% at MIC to 12.65 ± 0.55% at MIC/2 for ZAB-2.Tis variation was similar to that observed against another Gram-positive bacteria L. monocytogenes.ZAB-2 showed slightly higher antibioflm activity than ZAB-1 against Gram-positive bacteria.
Te antimicrobial efects of zirconium oxide material are demonstrated in this study while the absorption capacities have been reported in other reports.Metal oxides possess suitable properties for the removal of heavy metals, inorganic pollutants, and organic pollutants from wastewater and also killing microorganisms [85].Wastewater is the major cause of waterborne diseases such as deadly cholera and typhoid and usually contains bacteria and viruses as well Journal of Chemistry as toxic chemical substances and heavy metals.Metal oxides such as TiO 2 , ZnO, Ag 2 O, and CuO in addition to polymer/ metal oxide-based materials can use their photocatalytic degradation, adsorption, and antimicrobial activities as a multifaceted strategy to treat waste water [85,86].Most treatments for water are focused on removal of dirty particles and toxic chemicals while little attention is paid to health-threatening microorganisms [87][88][89].Te inhibitory efects against microorganisms by ZAB-1 and ZAB-2 ofer additional relevance as a suitable biocide for water treatment.Te alginate beads contribute in improving antimicrobial activity and also in avoiding the dispersion of the metal oxide particles in water after treatment.Polymermetal oxide nanocomposites are efcient disinfectants for water, and it was suggested that oxides of Ag, Ti, and Zn are able to inhibit various waterborne disease microbes owing to their charge capacity [10,90].To the best of our knowledge, this is the frst report of the biocidal efects of zirconium oxide-alginate beads.It can be observed that the antimicrobial activity in some cases increased with the increase in the percentage composition of alginate from 1.5% to 2.0%.Tis was the case with S. aureus, E. coli, and C. tropicalis.In some bacteria, the amount of alginate did not infuence the antimicrobial activity as seen in the cases of E. faecalis, L. monocytogenes, P. aeruginosa, S. Typhi, and C. albicans.
Alginate is amongst the nondigestible polysaccharides with antimicrobial and antibioflm potential and can be used as adjuvants in combined antimicrobial therapies.In one study, alginate (2-16%) exhibited signifcant inhibition of microbial growth and could also prevent bioflm formation [91].Tis could justify the fact that ZAB-2 (2% alginate) showed higher bioflm inhibition and antimicrobial activity on some test pathogens than ZAB-1 (1.5% alginate).Bioflms are a major cause of microbial resistance, and they can be established in almost any environment including water.Bioflms can be formed between one or more bacterial colonies and mixed bioflms are more resistant and can withstand common antibiotics, a lack of nutrients, and environmental stress.Many biopolymers such as chitosan, cellulose, starch, gelatine, collagen, alginates, pectin, hyaluronic acid, and fbrin are usually combined with antimicrobial substances to obtain biodegradable and biocompatible composites for antimicrobial applications [92].

Violacein Inhibition against C. violaceum CV12472 and
Anti-Quorum Sensing against C. violaceum CV026.Chromobacterium violaceum CV12472 is a bacterium that produces a violet-coloured pigment known as violacein while growing under normal conditions.Tis pigment can be easily measured, and its production represents a quorum sensing process in bacteria.Violacein synthesis in this Gram-negative bacterium is a QS-regulated expression infuenced by acylhomoserine lactones (AHLs) [93].Te MICs of the test samples on C. violaceum CV12472 were determined, and their violacein inhibition percentages were evaluated at MIC and sub-MIC concentrations and reported in Table 3. Te MIC values were found to be 0.625 mg/mL on C. violaceum CV026 is a biosensor and wild mutant strain, which is either incapable of producing autoinducers such as AHL or defcient in AHL synthase and therefore requires an exogenous source of AHL to enable it produce violacein.For this reason, it serves as an important tool for studying QS mechanisms involving QS inhibitors of the signal molecules [94,95].Te MIC values of the samples on C. violaceum CV026 were determined and reported in Table 4 alongside quorum sensing inhibition zone diameters against C. violaceum CV026 in the midst of an externally supplied AHL.Te MIC values against C. violaceum CV026 were found to be 0.625 mg/mL and 1.25 mg/mL for ZAB-1 and ZAB-2, respectively.Te anti-QS zone diameters were 13.0 ± 0.5 mm (ZAB-1) and 13.5 ± 0.8 mm (ZAB-2) at MIC and 9.6 ± 0.1 mm (ZAB-1) and 10.0 ± 0.5 mm (ZAB-2) at MIC/2.At MIC/4, only ZAB-2 had an inhibition zone of 7.5 ± 0.3 mm while none of the samples inhibited QS against C. violaceum CV026 at MIC/8.Tere were no signifcant diferences between the values of the anti-QS zones of both ZAB-1 and ZAB-2.
To efectively deal with resistant bioflm colonies, it is necessary to target quorum sensing networks since quorum sensing controls and regulates bioflm formation.Quorum sensing (QS) and bioflm disruption by the synthesized hydrated zirconium oxide-alginate beads provide an efcient strategy to prevent microbial infections and resistance.QS involves cell-to-cell communication in bacteria through the production and reception of small signal molecules called autoinducers which allow the bacteria to monitor their environment, population density, and control the expression of virulence genes and pathogenesis [96,97].Chromobacterium violaceum is a bacterium that occurs in various environments mostly in tropical regions, usually contaminates water and soils and can cause some rare and often fatal diseases.Tis bacterium is used as a model for quorum sensing (QS) inhibition.Shewanella spp., Aeromonas spp., Vibrio spp., and Chromobacterium violaceum are the four Gram-negative oxidase-positive bacteria which are usually associated with waterborne infections in tropical regions [98,99].It is therefore of great importance, as both ZAB-1 and ZAB-2 inhibited violacein production (QS) against the model organisms C. violaceum CV12472 and C. violaceum CV026.Tis bacterium produces a violet violacein pigment, a protective signal molecule which is easily measurable and represents a quorum sensing process [100].C. violaceum CV12472 has intrinsic secretion of AHL and produces violacein when growing normally, and a decrease in this pigment caused by antimicrobial samples represents violacein inhibition, an anti-QS process [101].QS systems inhibition is a strategy to block signal molecules like acylhomoserine lactone (AHL) from their biosynthesis or by degrading the AHL synthesized by the bacteria and/or inactivating receptor proteins for the produced AHL [91].Te synthesized hydrated zirconium oxide-alginate beads decreased the levels of violacein production, refected in a decrease in violet coloration, as shown on Figure 5. Te mutant strain C. violaceum CV026 equally failed to produce violacein within QS inhibition zones, as seen in Figure 5 as halos around the wells containing sample solutions at different concentrations.
Violacein inhibition assays with C. violaceum CV12472 indicated the potential inhibition of signal production while with C. violaceum CV026 indicated blockage of signal reception [6,[102][103][104][105][106].Te ability of the zirconium oxidealginate beads to show antimicrobial activity, antibioflm, and anti-QS potential on waterborne pathogens is a good indication that these materials can be suitable new biocides to treat infected water resources and avoid the development of resistant strains.

Swarming Motility Inhibition against P. aeruginosa PA01.
Substances that are able to inhibit virulence factors regulated by quorum sensing fnd applications as suitable therapies against infections and microbial resistance.Swarming motility is a virulence factor used by fagellated bacteria such as P. aeruginosa to move to nutrient-rich sites and targets.It also enables the bacteria to colonize surfaces and establish bioflms through the production of rhamnolipids on wet surfaces which facilitates swarming [107].Te fagellated P. aeruginosa PA01 was used in this assay and the diameters of growth (swarm diameters) on the plates were measured at 100 µg/mL, 75 µg/ml, and 50 µg/mL and used in calculating percentage inhibitions, and the results are presented in Table 5. Percentage inhibitions of swarming on P. aeruginosa PA01 were 25.1 ± 1.1% (ZAB-1) and 33.3 ± 1.2% (ZAB-2) at 100 µg/mL and 08.5 ± 0.2% (ZAB-1) and 17.5 ± 0.4% (ZAB-2) at 75 µg/mL and no inhibition of swarming was observed at 50 µg/mL.No signifcant diference was observed (p > 0.05) though the results indicated that ZAB-2 was slightly more active than ZAB-1.Te zirconium oxidealginate beads (ZAB-1 and ZAB-2) inhibited swarming motility in P. aeruginosa PA01, indicating that they can reduce the incidence of bioflms at an early stage and reduce the spread of bacteria.Tis is because bacteria use swarming motility to move towards nutrients and surfaces and then colonize the surfaces before forming bioflms [8,[108][109][110][111].
Swarming is facilitated by fagella and quorum sensing and usually involves the production of biosurfactants to reduce surface tension between bacteria cells and the surrounding environment and also pack them together in colonies [112].Terefore, the inhibition of swarming and bioflms by the zirconium oxide-alginate beads can reduce biofouling in water.Polymeric materials are new types of antimicrobials with antivirulence efects on various pathogens and diferent modes of action, fnding applications in multiple domains [113].Purifcation technology plays a crucial role in the production of safe drinking water.Te future prospects of this research will involve the development of safe bioflters from biodegradable polymers and metal oxides complexes which are endowed with antimicrobial efects.Biofltration involves the purifcation of water using substances which can remove inorganic, organic pollutants, turbidity, undesirable tastes, and odours as well as bacteria and viruses.It is therefore interesting to develop bioflters with biodegradable polymers such as alginate which are compatible with the environment and can help address the increasing demand for drinking water.Tis technology is gaining attention because of its numerous advantages.

Conclusions
Access to colourless and odourless water that is free from contaminants and germs is a global problem.Portable water is necessary for basic life processes, and therefore all living organisms need water for their survival.Te increasing population, rapid industrialization, and extensive agriculture lead to an increase in the contamination of available water resources.Many organic and inorganic chemical materials as well as some pathogenic microorganisms can get into water, and many techniques have been developed to efectively remove them while little attention is paid to the pathogenic bacteria that survive in water.Tis study reports the efects of synthesized hydrated zirconium metal oxidecoated alginate on some water-transmissible pathogenic bacteria.Te hydrated zirconium oxide encapsulated in alginate biopolymer beads was synthesized and characterized by FT-IR, XRD, and SEM.Tey displayed antimicrobial, antibioflm, and anti-QS properties on a range of waterborne bacteria.Te anti-QS and antibioflm efects indicated that the zirconium oxide-alginate material can prevent microbial resistance and biofouling of microbial communities in water.Te addition of alginate is believed to render the particles more biocompatible and enables them to be easily recoverable from water after usage.Te results therefore indicate the potential of treating water with zirconium oxide-alginate material as an environmentally friendly, nontoxic, and efcient strategy to inhibit waterborne microorganisms.

Figure 1 :
Figure 1: Scheme for the synthesis of hydrated zirconium oxide-coated alginate beads.

Table 1 :
Antimicrobial activity (MIC in mg/mL) of test samples.

Table 4 :
Quorum sensing inhibition zones in C. violaceum CV026 by samples.

Table 3 :
Violacein inhibition in C. violaceum CV12472 by the samples.