**9. Conclusion**

Survival of bacterial after disinfection and antibiotic treatment represents a problem for the modern medicine and industry practice. Commonly applied antibiotics and disinfectants are able to eliminate planktonic bacteria released from the biofilm but often are unable to treat biofilm-embedded cells. This may cause difficult to eradicate infectious.

Biofilm resistance to bactericidal agents is usually multifactorial and may vary from one microorganism to another. Environmental heterogeneity that exists inside the biofilm might promote the formation heterogeneous communities of bacteria, such that different levels of resistance can be employed throughout the entire population. For instant, the bacteria at periphery region of biofilm might be protected by the glycocalyx matrix, by the efflux systems and by the enzymes that inactivate certain antimicrobial compounds. The cells in the intermediate position of biofilm became starved for a particular nutrient, and they slow their growth. Transition from exponential to slow or no growth/persisters phenomena is also be accompanied by the increased in resistance of bacteria biofilm to bactericidal agents. Upon the extreme conditions setting the general stress response mechanism by surfacebound bacteria may prevents cellular damage.

Whatever new biocides/antibiotics are developed, the high number of bacteria within biofilms will combine to overcome their action and lead to resistance formation. The only way to avoid or to slow the speed of excess resistance formation is systematic and in-depth investigation of resistant bacteria isolated from naturally occurred biofilms. The information derived from lab investigations can provide insight strategies to subvert both biocide and antibiotic resistance of surface-bound bacteria.

#### **10. References**

224 Antimicrobial Agents

Numerous of works have focused on the identification of genes that could contribute efflux system-mediate resistance of bacterial biofilms. Maira-Litran et al. (2000) examined the systems of *mar* and *acrAB* that confer on *Escherichia coli* biofilm the multidrug resistance phenotype. The *mar* operon is a regulator controlling the expression of various genes in *Escherichia coli* cells constituting the *mar* regulon. Upregulation of *mar* in planktonic bacteria effects a resistance phenotype to antimicrobial agents such as antibiotics (penicillins, cephalosporins, rifampicin, nalidixic acid and fluoroquinolones), oxidative stress agents and organic solvents (Alekshun & Levy, 1997). *mar* can be induced by sub-lethal doses of commonly used therapeutics such as tetracycline, chloramphenicol, salicylate and paracetamol (Cohen et al., 1993; Seoane & Levy, 1995). The *acrAB* efflux pump is upregulated in *mar* mutants and determined the multidrug resistant phenotype of *mar* mutant isolates (Ma et al., 1995; Ma et al., 1996). According to Maira-Litran et al. (2000) the constitutive expression of *acrAB* efflux pump effects lower susceptibility of *Escherichia coli*  biofilm to sub-lethal doses of ciprofloxacin. In addition, the expression of *mar* and its target genes is related to stationary phase of bacteria growth. Authors observed the highest level of *mar* expression within the depth of *Escherichia coli* biofilm, where the metabolic activity of

Brooun et al. (2000) and De Kievit et al. (2001) examined the expression of the genes associated with efflux pumps (MexAB-OprM and MexCD-OprJ) in developing biofilms of *Pseudomonas aeruginosa*. Brooun et al. (2000) underscored the importance of these pumps in the resistance to ofloxacin. Authors demonstrated that at low concentration of ofloxacin *Pseudomonas aeruginosa* mature biofilm with lacking MexAB-OprM was less resistant to antibiotic than mature biofilm that overexpressed the pump (Brooun et al. 2000). De Kievit et al. (2001) found that expression of the genes that encode MexAB-OprM and MexCD-OprJ, are decreased over time during biofilm maturation. In addition, authors, using the overexpressing and efflux pumps mutants of *Pseudomonas aeruginosa* revealed that none of efflux pumps analyzed plays a significant role at decreasing susceptibility of *Pseudomonas aeruginosa* biofilm to antibiotics (De Kievit, et al., 2001). Therefore to assess the true function of efflux pump in bacterial biofilm resistance to antimicrobial agents, further experiments of

examined bacteria were the most suppressed (Maira-Litran et al., 2000).

additional not yet characterized loci with homology to efflux system are needed.

biofilm-embedded cells. This may cause difficult to eradicate infectious.

Survival of bacterial after disinfection and antibiotic treatment represents a problem for the modern medicine and industry practice. Commonly applied antibiotics and disinfectants are able to eliminate planktonic bacteria released from the biofilm but often are unable to treat

Biofilm resistance to bactericidal agents is usually multifactorial and may vary from one microorganism to another. Environmental heterogeneity that exists inside the biofilm might promote the formation heterogeneous communities of bacteria, such that different levels of resistance can be employed throughout the entire population. For instant, the bacteria at periphery region of biofilm might be protected by the glycocalyx matrix, by the efflux systems and by the enzymes that inactivate certain antimicrobial compounds. The cells in the intermediate position of biofilm became starved for a particular nutrient, and they slow their growth. Transition from exponential to slow or no growth/persisters phenomena is also be accompanied by the increased in resistance of bacteria biofilm to bactericidal agents.

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**11** 

*Brazil* 

**Antimicrobial Activity of** 

Daiani Savi2, Vania Aparecida Vicente2,

*Campo Grande, Mato Grosso do Sul* 

**Endophytes from Brazilian Medicinal Plants** 

The increased use of antibiotics has become the bacteria resistant. Currently, there are increasing problems worldwide with multiresistant bacteria. Examples of the resistance problems on a global scale are the methicillin-resistant *Staphylococcus aureus* (MRSA), vancomycin-resistant enterococci and *Enterobacteriaceae* producing beta-lactamases. A study of the *World Health Organization (WHO)* revealed that 90% of the bacteria strains are resistant to drugs of first choice. Bioprospecting studies of endophytic microorganisms for pharmaceutical and biotechnological purposes are fundamental for the discovery of new substances for human therapeutics including antibiotics, antimalarials, and anticarcinogenics (Strobel & Long 1998; Strobel 2002; Strobel & Daisy 2003). Endophytic fungi of medicinal plants are currently being widely studied in the search for new potentially useful secondary metabolites. The production of bioactive secondary metabolites by medicinal plants and by the endophytes provided countless drugs selected as important therapeutic options for innumerable disease. The endophytes still have wide potential to be explored what could expand even more the phenomenal contribution to health and well being. Aware of the reality of multi-resistant pathogenic microorganisms and the producing capacity of antimicrobial compounds by endophytes it is indispensable the search of antibiotic substances with new mechanisms of action, less toxic effect and/or medication enhance through this apparently inexhaustible bioactive metabolites source (Demain &

**1. Introduction** 

 \*

Corresponding Author

Chirlei Glienke1,\*, Fabiana Tonial2, Josiane Gomes-Figueiredo1,2,

Beatriz H. L. N. Sales Maia3 and Yvelise Maria Possiede4 *1Department of Genetics, Federal University of Parana (UFPR), Setor de Ciências Biológicas, Centro Politécnico, Curitiba, Paraná, 2Department of Basic Pathology, Federal University of Parana (UFPR), Setor de Ciências Biológicas, Centro Politécnico, Curitiba, Paraná, 3Department of Chemistry, Federal University of Parana (UFPR), Setor de Ciências Exatas, Centro Politécnico, Curitiba, Paraná, 4Department of Biology, Federal University of Mato Grosso do Sul,* 

