Abstract
Antimicrobial resistance to synthetic antimicrobial drugs has rekindled interest in natural antimicrobial compounds. Biofilms account for about 80% of total microbial infections in humans. This chapter explores the formation mechanism of biofilm which includes stages like: (i) adhesion, (ii) maturation, and (iii) differentiation, along with antimicrobial agent and antimicrobial activities of plant, spice, and herb derived components; their chemical potential and mode of action with examples of each. Biofilms use a quorum sensing communication system which varies according to types of gram-positive and gram-negative bacteria. Plants produce a wide range of bioactive molecules which possess antimicrobial activity making them a valuable source of pharmaceutical raw material. Herbs have been used for the past thousands of years and have many medicinal and other properties. Spices and condiments are used around the globe as key flavor and fragrance enhancers in various types of cuisines. This chapter explores the antimicrobial potential of plants, herbs, and spices.
TopAlthough both gram-positive and gram-negative bacteria can create biofilms, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus viridians, E. coli, Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa are the most frequent types (Table 1). S. aureus and S. epidermidis are thought to be responsible for roughly 40–50% of infections in prosthetic heart valves, 50–70% of infections in catheter biofilms, and 87% of infections in blood streams (Chen et al., 2013). The staphylococcal species are a large family of gram-positive bacteria that predominately live on human skin and other mammals' mucous membranes. The main culprits behind surgical site, bloodstream, and hospital acquired infections are S. aureus and S. epidermidis (Zaborowska et al., 2017).
Table 1. Major pathogen forming Biofilm
| Name of organism | Nature of cell wall |
| Enterococcus faecalis | Gram-positive |
| Staphylococcus aureus |
| Staphylococcus epidermidis |
| Streptococcus viridians |
| Escherichia coli | Gram-negative |
| Klebsiella pneumoniae |
Proteus mirabilis
Pseudomonas aeruginosa
Key Terms in this Chapter
Carminative agent: An agent that prevents or relieves flatulence (gas in the gastrointestinal tract) and, in infants, may help in the treatment of colic.
Biofilm: A biofilm is a complex multicellular community of bacteria adhered to biotic or abiotic surfaces and incorporated in a self-produced extracellular matrix.
Adhesion: Adhesion is the propensity for unrelated particles or surfaces to stick together.
Autoinducer Peptides: Gram-positive bacteria that participate in quorum sensing typically use secreted oligopeptides as autoinducers.
Quorum Sensing: The control of gene expression in response to changes in cell population density is known as quorum sensing. The concentration of chemical signal molecules known as autoinducers, which are produced and released by quorum sensing bacteria, rises with cell density.
Antimicrobial Agent: Antimicrobial agent is any of a large variety of chemical compounds and physical agents that are used to destroy microorganisms or to prevent their development.
Differentiation: Differentiation refers to the process by which unspecialized or less-specialized cells acquire specialized structures and functions.
Antimicrobial: Medicines used to prevent and treat infections in humans, animals and plants.