Biofilm Formation, Maturation and Prevention: A Review

Special Article - Biofilm

J Bacteriol Mycol. 2019; 6(1): 1092.

Biofilm Formation, Maturation and Prevention: A Review

Liaqat I¹*, Liaqat M², Ali S¹, Ali NM³, Haneef U4, Mirza SA4 and Tahir HM¹

¹Department of Zoology, GC University, Lahore, Pakistan

²Department of Nursing, Allama Iqbal Medical College, Lahore

³Govt. College for Women, Model Town, Lahore

4Department of Botany, GC University, Lahore, Pakistan

*Corresponding author: Iram Liaqat, Department of Zoology, GC University, Lahore, Pakistan

Received: December 11, 2018; Accepted: January 08, 2019; Published: January 15, 2019


Biofilms are groups of microrganisms in which cells embedded in extracellular polysaccharide matrix (EPS) stick to each other on a surface. Bacterial polysaccharide is the major component of biofilm matrix and make it stable as well as resistant to disinfectants, biocides and antibiotics. Biofilms can be harmful or beneficial, however unfortunately negative effects outweighs the positive ones. Formation of biofilm may take place on both biotic and abiotic surfaces and may be monospecies or multispecies. Though multispecies biofilm are more prevalent in nature augmenting the need to communicate between inter and intra species. In fact, biofilm formation and quorum sensing (QS) are interconnected. Quorum sensing (QS) is a regulatory system that allows bacteria to produce and detect signal molecules and thereby communicate their behaviour in a cell-density dependent manner. Three main QS systems include: The acylhomoserine lactone (AHL) QS system in Gram-negative bacteria, the autoinducing peptide (AIP) QS system in Gram-positive bacteria and the autoinducer-2 (AI-2) QS system in both Gram-negative and -positive bacteria. Biofilm formation and associated problems are a serious emerging issue in household, industry and medical settings. Many antibiofilm strategies were suggested to cope with its formation rather than removal. Among these, four commonly include are: (1) use of broad spectrum antibiotics/biocides, (2) interference with bacterial EPS production, (3) quorum sensing (QS), and (4) flagellar assembly. A comprehensive knowledge of bacterial biofilm will help to develop effective control measures to prevent its formation at initial stages and to manage associated problems later, once developed and got mature completely.

Keywords: Biofilms; Autoaggregation; Prevention Strategies; Quorum Sensing; Bacterial Exopolymeric Compounds


For more than 10 decades, microbiologists have studied homogeneous culture format of bacteria leading to tremendously informative physiology and genetics but biased picture of microbial life. Since the last 10 years, the concept of biofilms has gained enough significance and popularity. The fact about 99% of bacterial population exhibit biofilm mode at some stage in life has nourished maximally to this area of research. Bacterial aggregation happens due to numerous advantageous reasons including survival in extremely dynamic habitats sometimes with nutrient depletion, resistance to broad spectrum antibiotics, disinfectants and various phenotypic variations [1].

Biofilm is a structured consortium attached to a living or inert surface formed by microorganism adhering to each other and selfproduced extracellular polymeric substance (EPS). Depending upon species type, it comprise of 10-25 % cells and 75-90 % extracellular polymeric substances (EPS) matrix [2]. This indicates that EPS is much more than just a sticky substance that holds cells together. Indeed, the matrix imbues the biofilm with a range of attributes, including antibiotic resistance, storage of extracellular enzymes, nutrient capture, gradient formation and protection from stress that single cells or planktonic cells cannot achieve in its absence. In this way, the matrix is truly responsible for the emergent properties of the biofilm [3].

Biofilm research has become a revolutionized field and evolved tremendously with the advancement in computational sciences, various molecular techniques and omics’ based technologies. Despite the fact, that monoculture of bacteria is easy to study and manipulate, it’s also undeniable to accept that none of the habitat is occupied by just single bacterial species. There is always interaction and communication between different species microrganisms in any locality to make a stable community. Hence research in this emerging field of biofilm has led to development of new techniques and additional models [4], to understand its structure and mechanism. Researchers have answered questions for example, Multispecies biofilm is more stable and require less nutrients compared to monospecies biofilm [5,6]. It has increased tolerance to disinfectants, antimicrobials and predation [7]. Likewise, autotroph-heterotroph interactions, interaction, competition and cooperation between diverse microbial species using chemical signals [8], are all newly investigated areas of research.

Biofilm may be formed by a single bacterial species that makes it a monoculture also called monofilms or diverse species of bacteria may be involved in its structure, hence called as multiculture (also multifilms). Both types act as biocatalysts during different processes to transform organic substances. Monofilms are important to control the processes required for increased yield and quality of a desired product, whereas multispecies are valuable for multistage processes of biogas production and pharmaceutical formulations [9]. Quorum sensing (QS) plays key role to control mono and multispecies biofilm formation and other social/physiological behaviours including symbiosis, formation of spore or fruiting bodies, bacteriocin production, genetic competence, programmed cell death, virulence [10]. This process of intercellular communication, called quorum sensing, was first described in the marine bioluminescent bacterium Vibrio fischeri. In this system, bacteria in a community convey their presence by producing, detecting, and responding to small diffusible signal molecules called autoinducers. Bacterial QS system has generally been divided into three types: (1) Gram-negative bacteria use acyl-homoserine lactones (AHL) as signal molecules- LuxI/LuxR– type quorum sensing; (2) Gram-positive bacteria use small peptides as signal molecules called as oligopeptide-two-component-type QS (3) Both Gram-negative and Gram-positive bacteria has common luxSencoded autoinducer 2 (AI-2) QS. Each type of signalling system is detected and responded by proper sensing apparatus and regulatory control [11].

The implementation of any process of biofilms from biotechnology perspective require complete information of microrganisms involved in its formation. In general, it is a multistep process. First step is the process of bacterial attachment to either biotic or abiotic surfaces. Afterwards the attached cells mature and are enclosed in self produced extracellular polymeric substance (EPS), which is formed by a combination of proteins, polysaccharides and other biomolecules. It is responsible for three dimensional architectural form and stabilization of biofilms. It may be linear or branched molecules formed by one repeated sugar (homopolysaccharides) or by a mixture of different sugars (heteropolysaccharides). In final step, planktonic cells detach from biofilm matrix and start process again at new process (Figure 1) [12]. It is believed that environmental signals, flagella, outer membrane proteins, pili, or LPSs collectively led to the formation of microcolonies which becomes mature biofilm using QS molecules [13]. However, scientists are still looking for answers of questions concerning mechanisms involved in bacterial sensing of surface and development of different stages during biofilm development [14].

Citation: Liaqat I, Liaqat M, Ali S, Ali NM, Haneef U, Mirza SA, et al. Biofilm Formation, Maturation and Prevention: A Review. J Bacteriol Mycol. 2019; 6(1): 1092.