Preface

A biofilm is a microbial form of life formed by the organic exopolysaccharide structures produced by microorganisms, irreversibly attached to a living or inanimate interface. Today, biofilms are widespread in nature and produced by many bacteria.

Biofilms protect bacteria from changes in environmental conditions and the harmful effects of ultraviolet light, making it easier for the bacteria to store food and remove waste materials. Due to biofilms, it is difficult for microorganisms to undergo phagocytosis by the immune system cells. When favorable conditions occur, biofilms can be created by pathogenic microorganisms. Bacterial attachment levels, surface properties, temperature, type and number of bacteria, pH of the environment, cell-wall structure of the bacteria, mobility, amount and content of the nutrients in the environment, and ion concentration all affect biofilm formation. Microorganisms create biofilms for reasons such as protection from the harmful effects of the environment as well as obtainment of nutrients and new genetic features. Biofilm formation is not a random event, and many microorganisms signal each other using small diffuse molecules to coordinate activities.

The intercellular communication required for biofilm formation is provided by a system called "quorum sensing." This system provides many advantages to bacteria, but it also controls the formation of biofilms through signals transmitted from cell to cell. While the quorum sensing system detects the population density around the bacteria, the bacteria provide gene control. In addition to developing coordination between food sources and bacteria, quorum sensing also increases communication with the bacteria during infection to develop resistance to the immune response in the host.

Studies have shown that bacteria living in biofilms are more resistant to antibacterial agents, iodine, the iodine polyvinylpyrrolidone complex, chlorine, monochloramine, pyrogens and biocides, and heat.

Biofilms are known to cause economic losses due to their negative effects in many areas, especially in health and food. New methods incorporating enzymes, detergents, ultrasound, and electricity are being used to control and prevent bacteria via mechanical cleaning, use of biocides, preventing biofilm development, preventing microbial adhesions, and supporting biomass extraction. However, the effectiveness of each methods varies according to the applied surface, the type of bacteria that forms the biofilm, and the application methods.

Biofilms can cause great industrial losses and threaten public health. Therefore, more research is needed to understand biofilms and develop efficient ways of preventing their formation.

> **Sadık Dincer** Cukurova University, Adana, Turkey

**Melis Sümengen Özdenefe** Near East University,

Nicosia, Turkish Republic of Northern Cyprus

**Afet Arkut**

**1**

Section 1

Biofilm in Wastewater

Treatment

Cyprus International University, Nicosia, Turkish Republic of Northern Cyprus Section 1
