Extracellular polymeric substance matrix formation in a biofilm

Extracellular polymeric substances (EPSs) are natural polymers of high molecular weight secreted by microorganisms into their environment.[1] EPSs establish the functional and structural integrity of biofilms, and are considered the fundamental component that determines the physicochemical properties of a biofilm.[2] EPS in the matrix of biofilms provides compositional support and protection of microbial communities from the harsh environments.[3] Components of EPS can be of different classes of polysaccharides, lipids, nucleic acids, proteins, lipopolysaccharides, and minerals.

Components

EPSs are mostly composed of polysaccharides (exopolysaccharides) and proteins, but include other macromolecules such as DNA, lipids and humic substances. EPSs are the construction material of bacterial settlements and either remain attached to the cell's outer surface, or are secreted into its growth medium. These compounds are important in biofilm formation and cells' attachment to surfaces. EPSs constitute 50% to 90% of a biofilm's total organic matter.[2][4][5]

Exopolysaccharides (also sometimes abbreviated EPSs; EPS sugars thereafter) are the sugar-based parts of EPS. Microorganisms synthesize a wide spectrum of multifunctional polysaccharides including intracellular polysaccharides, structural polysaccharides and extracellular polysaccharides or exopolysaccharides. Exopolysaccharides generally consist of monosaccharides and some non-carbohydrate substituents (such as acetate, pyruvate, succinate, and phosphate). Owing to the wide diversity in composition, exopolysaccharides have found diverse applications in various food and pharmaceutical industries. Many microbial EPS sugars provide properties that are almost identical to the gums currently in use. With innovative approaches, efforts are underway to supersede the traditionally used plant and algal gums by their microbial counterparts. Moreover, considerable progress has been made in discovering and developing new microbial EPS sugars that possess novel industrial applications.[6] Levan produced by Pantoea agglomerans ZMR7 was reported to decrease the viability of rhabdomyosarcoma (RD) and breast cancer (MDA) cells compared with untreated cancer cells. In addition, it has high antiparasitic activity against the promastigote of Leishmania tropica.[7] In the1960s and 1970s, the presence of exopolysaccharides in the matrix of plaques associated with tooth decay was investigated.[8] In the field of paleomicrobiology, dental biofilms and their EPS components provide scientists with information about the composition of ancient microbial and host biomolecules as well as the diet of the host.[9]

The minerals, results of biomineralization processes regulated by the environment or bacteria, are also essential components of the EPS. They provide structural integrity to biofilm matrix and act as a scaffold to protect bacterial cells from shear forces and antimicrobial chemicals.[10] The minerals in EPS were found to contribute to morphogenesis of bacteria and the structural integrity of the matrix. For example, in Bacillus subtilis, Mycobacterium smegmatis, and Pseudomonas aeruginosa biofilms, calcite (CaCO3) contributes to the integrity of the matrix. The minerals also associate with medical conditions. In the biofilms of Proteus mirabilis, Proteus vulgaris, and Providencia rettgeri, the minerals calcium and magnesium cause catheter encrustation.[11]

Biofilm

Biofilm formation

The first step in the formation of biofilms is adhesion. The initial bacterial adhesion to surfaces involves the adhesin–receptor interactions. Certain polysaccharides, lipids and proteins in the matrix function as the adhesive agents. EPS also promotes cell–cell cohesion (including interspecies recognition) to facilitate microbial aggregation and biofilm formation.[12] In general, the EPS-based matrix mediates biofilm assembly as follows. First, the EPS formation takes place at the site of adhesion, it will be either produced on bacterial surfaces or secreted on the surface of attachment, and form an initial polymeric matrix promoting microbial colonization and cell clustering. Next, continuous production of EPS further expands the matrix in 3 dimensions while forming a core of bacterial cells. The bacterial core provides a supporting framework, and facilitates the development of 3D clusters and aggregation of microcolonies.[13] Studies on P. aeruginosa, B. subtilis, V. cholerae, and S. mutans suggested that the transition from initial cell clustering to microcolony appears to be conserved among different biofilm-forming model organisms.[13] As an example, S. mutans produces an exoenzymes, called glucosyltransferases (Gtfs), which synthesize glucans in situ using host diet sugars as substrates. Gtfs even bind to the bacteria that do not synthesize Gtfs, and therefore, facilitate interspecies and interkingdom coadhesion.[14]

Significance in biofilms

Afterwards, as biofilm becomes established, EPS provides physical stability and resistance to mechanical removal, antimicrobials, and host immunity. Exopolysaccharides and environmental DNA (eDNA) contribute to viscoelasticity of mature biofilms so that detachment of biofilm from the substratum will be challenging even under sustained fluid shear stress or high mechanical pressure.[15] In addition to mechanical resistance, EPS also promotes protection against antimicrobials and enhanced drug tolerance.[16] Antimicrobials cannot diffuse through the EPS barrier, resulting in limited drug access into the deeper layers of the biofilm.[17] Moreover, positively charged agents will bind to negatively charged EPS contributing to the antimicrobial tolerance of biofilms, and enabling inactivation or degradation of antimicrobials by enzymes present in biofilm matrix. EPS also functions as local nutrient reservoir of various biomolecules, such as fermentable polysaccharides.[18] A study on V. cholerae in 2017 suggested that due to osmotic pressure differences in V. cholerae biofilms, the microbial colonies physically swell, therefore maximizing their contact with nutritious surfaces and thus, nutrient uptake.[19]

Function

Capsular exopolysaccharides can protect pathogenic bacteria against desiccation and predation, and contribute to their pathogenicity.[20] Sessile bacteria fixed and aggregated in biofilms are less vulnerable compared to drifting planktonic bacteria, as the EPS matrix is able to act as a protective diffusion barrier.[21] The physical and chemical characteristics of bacterial cells can be affected by EPS composition, influencing factors such as cellular recognition, aggregation, and adhesion in their natural environments.[21] Furthermore, the EPS layer acts as a nutrient trap, facilitating bacterial growth.[21] The exopolysaccharides of some strains of lactic acid bacteria, e.g., Lactococcus lactis subsp. cremoris, contribute a gelatinous texture to fermented milk products (e.g., Viili), and these polysaccharides are also digestible.[22][23] An example of the industrial use of exopolysaccharides is the application of dextran in panettone and other breads in the bakery industry.[24]

Apart from negative contributions of EPS in biofilms, EPS can also contribute to some beneficial functions. For example, B. subtilis has gained interest for its probiotic properties due to its biofilm which allows it to effectively maintain a favorable microenvironment in the gastrointestinal tract. In order to survive the passage through the upper gastrointestinal tract, B. subtilis produces an extracellular matrix that protects it from stressful environments such as the highly acidic environment in the stomach.[25] In B. subtilis, the protein matrix component, TasA, and the exopolysaccharide have both been shown to be essential for effective plant-root colonization in Arabidopsis and tomato plants.[16] It was also suggested that TasA plays an important role in mediating interspecies aggregation with streptococci.[26]

Ecology

Exopolysaccharides can facilitate the attachment of nitrogen-fixing bacteria to plant roots and soil particles, which mediates a symbiotic relationship.[20] This is important for colonization of roots and the rhizosphere, which is a key component of soil food webs and nutrient cycling in ecosystems. It also allows for successful invasion and infection of the host plant.[20] Bacterial extracellular polymeric substances can aid in bioremediation of heavy metals as they have the capacity to adsorb metal cations, among other dissolved substances.[27] This can be useful in the treatment of wastewater systems, as biofilms are able to bind to and remove metals such as copper, lead, nickel, and cadmium.[27] The binding affinity and metal specificity of EPSs varies, depending on polymer composition as well as factors such as concentration and pH.[27] In a geomicrobiological context, EPSs have been observed to affect precipitation of minerals, particularly carbonates.[28] EPS may also bind to and trap particles in biofilm suspensions, which can restrict dispersion and element cycling.[28] Sediment stability can be increased by EPS, as it influences cohesion, permeability, and erosion of the sediment.[28] There is evidence that the adhesion and metal-binding ability of EPS affects mineral leaching rates in both environmental and industrial contexts.[28] These interactions between EPS and the abiotic environment allow for EPS to have a large impact on biogeochemical cycling. Predator-prey interactions between biofilms and bacterivores, such as the soil-dwelling nematode Caenorhabditis elegans, had been extensively studied. Via the production of sticky matrix and formation of aggregates, Yersinia pestis biofilms can prevent feeding by obstructing the mouth of C. elegans.[29] Moreover, Pseudomonas aeruginosa biofilms can impede the slithering motility of C. elegans, termed as 'quagmire phenotype', resulting in trapping of C. elegans within the biofilms and preventing the exploration of nematodes to feed on susceptible biofilms.[30] This significantly reduced the ability of predator to feed and reproduce, thereby promoting the survival of biofilms.

Novel industrial use

Due to the growing need to find a more efficient and environmentally friendly alternative to conventional waste removal methods, industries are paying more attention to the function of bacteria and their EPS sugars in bioremediation.[31]

Researchers found that adding EPS sugars from cyanobacteria to wastewaters removes heavy metals such as copper, cadmium and lead.[31] EPS sugars alone can physically interact with these heavy metals and take them in through biosorption.[31] The efficiency of removal can be optimized by treating the EPS sugars with different acids or bases before adding them to wastewater.[31] Some contaminated soils contain high levels of polycyclic aromatic hydrocarbons (PAHs); EPSs from the bacterium Zoogloea sp. and the fungus Aspergillus niger, are efficient at removing these toxic compounds.[32] EPSs contain enzymes such as oxidoreductase and hydrolase, which are capable of degrading PAHs.[32] The amount of PAH degradation depends on the concentration of EPSs added to the soil. This method proves to be low cost and highly efficient.[32]

In recent years, EPS sugars from marine bacteria have been found to speed up the cleanup of oil spills.[33] During the Deepwater Horizon oil spill in 2010, these EPS-producing bacteria were able to grow and multiply rapidly.[33] It was later found that their EPS sugars dissolved the oil and formed oil aggregates on the ocean surface, which sped up the cleaning process.[33] These oil aggregates also provided a valuable source of nutrients for other marine microbial communities. This let scientists modify and optimize the use of EPS sugars to clean up oil spills.[33]

List of EPSes

Succinoglycan from Sinorhizobium meliloti

New approaches to target biofilms

The application of nanoparticles (NPs) are one of novel promising techniques to target biofilms due to their high surface-area-to-volume ratio, their ability to penetrate to the deeper layers of biofilms and the capacity to releasing antimicrobial agents in a controlled way. Studying NP-EPS interactions could provide deeper understanding on how to develop more effective nanoparticles.[3] "smart release" nanocarriers that can penetrate biofilms and be triggered by pathogenic microenvironments to deliver drugs or multifunctional compounds, such as catalytic nanoparticles to aptamers, dendrimers, and bioactive peptides) have been developed to disrupt the EPS and the viability or metabolic activity of the embedded bacteria. Some factors that would alter the potentials of the NP to transport antimicrobial agents into the biofilm include physicochemical interactions of the NPs with EPS components, the characteristics of the water spaces (pores) within the EPS matrix and the EPS matrix viscosity.[34] Size and surface properties (charge and functional groups) of the NPs are the major determinants of the penetration in and the interaction with the EPS.[3] Another potential antibiofilm strategy is phage therapy. Bacteriophages, viruses that invade specific bacterial host cells, were suggested to be effective agents in penetrating biofilms.[11] In order to reach the maximum efficacy to eradicate biofilms, therapeutic strategies need to target both the biofilm matrix components as well as the embedded microorganisms to target the complex biofilm microenvironment.[11]

In microalgal biofilms

EPS is found in the matrix of other microbial biofilms such as microalgal biofilms. The formation of biofilm and structure of EPS share a lot of similarities with bacterial ones. The formation of biofilm starts with reversible absorption of floating cells to the surface. Followed by production of EPS, the adsorption will get irreversible. EPS will colonize the cells at the surface with hydrogen bonding. Replication of early colonizers will be facilitated by the presence of organic molecules in the matrix which will provide nutrients to the algal cells. As the colonizers are reproducing, the biofilm grows and becomes a 3-dimensional structure.[35] Microalgal biofilms consist of 90% EPS and 10% algal cells. Algal EPS has similar components to the bacterial one; it is made up of proteins, phospholipids, polysaccharides, nucleic acids, humic substances, uronic acids and some functional groups, such as phosphoric, carboxylic, hydroxyl and amino groups. Algal cells consume EPS as their source of energy and carbon.[36] Furthermore, EPS protects them from dehydration and reinforces the adhesion of the cells to the surface. In algal biofilms, EPS has two sub-categories; soluble EPS (sEPS) and the bounded EPS (bEPS) with former being distributed in the medium and the latter being attached to the algal cells.[37] Bounded EPS can be further subdivided to tightly bounded EPS (TB-EPS) and loosely bounded EPS (LB-EPS). Several factors contribute to the composition of EPS including species, substrate type, nutrient availability, temperature, pH and light intensity.[38]

See also

References

  1. ^ Staudt C, Horn H, Hempel DC, Neu TR (December 2004). "Volumetric measurements of bacterial cells and extracellular polymeric substance glycoconjugates in biofilms". Biotechnology and Bioengineering. 88 (5): 585–592. doi:10.1002/bit.20241. PMID 15470707.
  2. ^ a b Flemming HC, Wingender J, Griebe T, Mayer C (December 21, 2000). "Physico-Chemical Properties of Biofilms". In Evans LV (ed.). Biofilms: Recent Advances in their Study and Control. CRC Press. p. 20. ISBN 978-9058230935.
  3. ^ a b c Fulaz S, Vitale S, Quinn L, Casey E (November 2019). "Nanoparticle-Biofilm Interactions: The Role of the EPS Matrix". Trends in Microbiology. 27 (11): 915–926. doi:10.1016/j.tim.2019.07.004. PMID 31420126. S2CID 201042373.
  4. ^ Donlan RM (September 2002). "Biofilms: microbial life on surfaces". Emerging Infectious Diseases. 8 (9): 881–890. doi:10.3201/eid0809.020063. PMC 2732559. PMID 12194761.
  5. ^ Donlan RM, Costerton JW (April 2002). "Biofilms: survival mechanisms of clinically relevant microorganisms". Clinical Microbiology Reviews. 15 (2): 167–193. doi:10.1128/CMR.15.2.167-193.2002. PMC 118068. PMID 11932229.
  6. ^ Kumar AS, Mody K (2009). "Microbial Exopolysaccharides: Variety and Potential Applications". Microbial Production of Biopolymers and Polymer Precursors. Caister Academic Press. ISBN 978-1-904455-36-3.[page needed]
  7. ^ Al-Qaysi SA, Al-Haideri H, Al-Shimmary SM, Abdulhameed JM, Alajrawy OI, Al-Halbosiy MM, et al. (May 2021). "Bioactive Levan-Type Exopolysaccharide Produced by Pantoea agglomerans ZMR7: Characterization and Optimization for Enhanced Production". Journal of Microbiology and Biotechnology. 31 (5): 696–704. doi:10.4014/jmb.2101.01025. PMC 9705920. PMID 33820887.
  8. ^ Bowen WH, Guggenheim B (January 1978). "Therapeutics of caries prevention--concepts and prospects". Acta Odontologica Scandinavica. 36 (4): 185–198. doi:10.3109/00016357809004667. PMID 280114.
  9. ^ Huynh HT, Verneau J, Levasseur A, Drancourt M, Aboudharam G (June 2016). "Bacteria and archaea paleomicrobiology of the dental calculus: a review". Molecular Oral Microbiology. 31 (3): 234–242. doi:10.1111/omi.12118. PMID 26194817.
  10. ^ Dade-Robertson M, Keren-Paz A, Zhang M, Kolodkin-Gal I (September 2017). "Architects of nature: growing buildings with bacterial biofilms". Microbial Biotechnology. 10 (5): 1157–1163. doi:10.1111/1751-7915.12833. PMC 5609236. PMID 28815998.
  11. ^ a b c Karygianni L, Ren Z, Koo H, Thurnheer T (August 2020). "Biofilm Matrixome: Extracellular Components in Structured Microbial Communities". Trends in Microbiology. 28 (8): 668–681. doi:10.1016/j.tim.2020.03.016. PMID 32663461. S2CID 219087510.
  12. ^ Flemming HC, Wingender J, Szewzyk U, Steinberg P, Rice SA, Kjelleberg S (August 2016). "Biofilms: an emergent form of bacterial life". Nature Reviews. Microbiology. 14 (9): 563–575. doi:10.1038/nrmicro.2016.94. PMID 27510863. S2CID 4384131.
  13. ^ a b Wang C, Hou J, van der Mei HC, Busscher HJ, Ren Y (September 2019). "Emergent Properties in Streptococcus mutans Biofilms Are Controlled through Adhesion Force Sensing by Initial Colonizers". mBio. 10 (5). doi:10.1128/mbio.01908-19. PMC 6737243. PMID 31506311.
  14. ^ Hwang G, Liu Y, Kim D, Li Y, Krysan DJ, Koo H (June 2017). Mitchell TJ (ed.). "Candida albicans mannans mediate Streptococcus mutans exoenzyme GtfB binding to modulate cross-kingdom biofilm development in vivo". PLOS Pathogens. 13 (6): e1006407. doi:10.1371/journal.ppat.1006407. PMC 5472321. PMID 28617874.
  15. ^ Peterson BW, He Y, Ren Y, Zerdoum A, Libera MR, Sharma PK, et al. (March 2015). "Viscoelasticity of biofilms and their recalcitrance to mechanical and chemical challenges". FEMS Microbiology Reviews. 39 (2): 234–245. doi:10.1093/femsre/fuu008. PMC 4398279. PMID 25725015.
  16. ^ a b Hobley L, Harkins C, MacPhee CE, Stanley-Wall NR (September 2015). "Giving structure to the biofilm matrix: an overview of individual strategies and emerging common themes". FEMS Microbiology Reviews. 39 (5): 649–669. doi:10.1093/femsre/fuv015. PMC 4551309. PMID 25907113.
  17. ^ Karygianni L, Ruf S, Follo M, Hellwig E, Bucher M, Anderson AC, et al. (December 2014). "Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A". Applied and Environmental Microbiology. 80 (23): 7324–7336. Bibcode:2014ApEnM..80.7324K. doi:10.1128/aem.02490-14. PMC 4249165. PMID 25239897.
  18. ^ Cugini C, Shanmugam M, Landge N, Ramasubbu N (July 2019). "The Role of Exopolysaccharides in Oral Biofilms". Journal of Dental Research. 98 (7): 739–745. doi:10.1177/0022034519845001. PMC 6589894. PMID 31009580.
  19. ^ Yan J, Nadell CD, Stone HA, Wingreen NS, Bassler BL (August 2017). "Extracellular-matrix-mediated osmotic pressure drives Vibrio cholerae biofilm expansion and cheater exclusion". Nature Communications. 8 (1): 327. Bibcode:2017NatCo...8..327Y. doi:10.1038/s41467-017-00401-1. PMC 5569112. PMID 28835649.
  20. ^ a b c Ghosh PK, Maiti TK (2016). "Structure of Extracellular Polysaccharides (EPS) Produced by Rhizobia and their Functions in Legume–Bacteria Symbiosis: — A Review". Achievements in the Life Sciences. 10 (2): 136–143. doi:10.1016/j.als.2016.11.003.
  21. ^ a b c Harimawan A, Ting YP (October 2016). "Investigation of extracellular polymeric substances (EPS) properties of P. aeruginosa and B. subtilis and their role in bacterial adhesion". Colloids and Surfaces. B, Biointerfaces. 146: 459–467. doi:10.1016/j.colsurfb.2016.06.039. PMID 27395039.
  22. ^ Welman AD (2009). "Exploitation of Exopolysaccharides from lactic acid bacteria". Bacterial Polysaccharides: Current Innovations and Future Trends. Caister Academic Press. ISBN 978-1-904455-45-5.[page needed]
  23. ^ Ljungh A, Wadstrom T, eds. (2009). Lactobacillus Molecular Biology: From Genomics to Probiotics. Caister Academic Press. ISBN 978-1-904455-41-7.[page needed]
  24. ^ Ullrich M, ed. (2009). Bacterial Polysaccharides: Current Innovations and Future Trends. Caister Academic Press. ISBN 978-1-904455-45-5.[page needed]
  25. ^ Yahav S, Berkovich Z, Ostrov I, Reifen R, Shemesh M (2018-05-27). "Encapsulation of beneficial probiotic bacteria in extracellular matrix from biofilm-forming Bacillus subtilis". Artificial Cells, Nanomedicine, and Biotechnology. 46 (sup2): 974–982. doi:10.1080/21691401.2018.1476373. PMID 29806505. S2CID 44100145.
  26. ^ Duanis-Assaf D, Duanis-Assaf T, Zeng G, Meyer RL, Reches M, Steinberg D, Shemesh M (June 2018). "Cell wall associated protein TasA provides an initial binding component to extracellular polysaccharides in dual-species biofilm". Scientific Reports. 8 (1): 9350. Bibcode:2018NatSR...8.9350D. doi:10.1038/s41598-018-27548-1. PMC 6008451. PMID 29921978.
  27. ^ a b c Pal A, Paul AK (March 2008). "Microbial extracellular polymeric substances: central elements in heavy metal bioremediation". Indian Journal of Microbiology. 48 (1): 49–64. doi:10.1007/s12088-008-0006-5. PMC 3450203. PMID 23100700.
  28. ^ a b c d Tourney J, Ngwenya BT (2014-10-29). "The role of bacterial extracellular polymeric substances in geomicrobiology". Chemical Geology. 386 (Supplement C): 115–132. Bibcode:2014ChGeo.386..115T. doi:10.1016/j.chemgeo.2014.08.011.
  29. ^ Atkinson S, Goldstone RJ, Joshua GW, Chang CY, Patrick HL, Cámara M, et al. (January 2011). "Biofilm development on Caenorhabditis elegans by Yersinia is facilitated by quorum sensing-dependent repression of type III secretion". PLOS Pathogens. 7 (1): e1001250. doi:10.1371/journal.ppat.1001250. PMC 3017118. PMID 21253572.
  30. ^ Chan SY, Liu SY, Seng Z, Chua SL (January 2021). "Biofilm matrix disrupts nematode motility and predatory behavior". The ISME Journal. 15 (1): 260–269. doi:10.1038/s41396-020-00779-9. PMC 7852553. PMID 32958848.
  31. ^ a b c d Mota R, Rossi F, Andrenelli L, Pereira SB, De Philippis R, Tamagnini P (September 2016). "Released polysaccharides (RPS) from Cyanothece sp. CCY 0110 as biosorbent for heavy metals bioremediation: interactions between metals and RPS binding sites". Applied Microbiology and Biotechnology. 100 (17): 7765–7775. doi:10.1007/s00253-016-7602-9. PMID 27188779. S2CID 15287887.
  32. ^ a b c Jia C, Li P, Li X, Tai P, Liu W, Gong Z (August 2011). "Degradation of pyrene in soils by extracellular polymeric substances (EPS) extracted from liquid cultures". Process Biochemistry. 46 (8): 1627–1631. doi:10.1016/j.procbio.2011.05.005.
  33. ^ a b c d Gutierrez T, Berry D, Yang T, Mishamandani S, McKay L, Teske A, Aitken MD (27 June 2013). "Role of Bacterial Exopolysaccharides (EPS) in the Fate of the Oil Released during the Deepwater Horizon Oil Spill". PLOS ONE. 8 (6): e67717. Bibcode:2013PLoSO...867717G. doi:10.1371/journal.pone.0067717. PMC 3694863. PMID 23826336.
  34. ^ Miller KP, Wang L, Benicewicz BC, Decho AW (November 2015). "Inorganic nanoparticles engineered to attack bacteria". Chemical Society Reviews. 44 (21): 7787–807. doi:10.1039/c5cs00041f. PMID 26190826.
  35. ^ Seviour T, Derlon N, Dueholm MS, Flemming HC, Girbal-Neuhauser E, Horn H, et al. (March 2019). "Extracellular polymeric substances of biofilms: Suffering from an identity crisis". Water Research. 151: 1–7. doi:10.1016/j.watres.2018.11.020. hdl:11311/1071879. PMID 30557778. S2CID 56174167.
  36. ^ Schnurr PJ, Allen DG (December 2015). "Factors affecting algae biofilm growth and lipid production: A review". Renewable and Sustainable Energy Reviews. 52: 418–429. doi:10.1016/j.rser.2015.07.090. ISSN 1364-0321.
  37. ^ Li N, Liu J, Yang R, Wu L (October 2020). "Distribution, characteristics of extracellular polymeric substances of Phanerochaete chrysosporium under lead ion stress and the influence on Pb removal". Scientific Reports. 10 (1): 17633. Bibcode:2020NatSR..1017633L. doi:10.1038/s41598-020-74983-0. PMC 7572388. PMID 33077860.
  38. ^ Cheah YT, Chan DJ (December 2021). "Physiology of microalgal biofilm: a review on prediction of adhesion on substrates". Bioengineered. 12 (1): 7577–7599. doi:10.1080/21655979.2021.1980671. PMC 8806711. PMID 34605338.

External links

Categories