Chemically Modified Natural Substances Screening for Biofilms Inhibition and Biofouling Control

Abstract

Biofilms can be characterized as a microorganisms community attached to a surface and enveloped by an extra polymeric substances complex array in a moist environment. It is known that the growth and formation way of the biofilm structure induces resistance to several microbial agents, making it impossible to disintegrate and eliminate these structures. These biofilms can settle in the vessels surface, pipes, thermoelectric cooling systems and so forth causing serious economic problems in the most diverse strategic sectors of a country such as nautical, industrial, energy. Search for substances capable of disturbing this formation is desired, since the formation of the biofilm is the crucial stage for the emergence of new organisms that will develop until the climax of the ecological succession with the arrival of macrofouling. These substances when isolated can be ideal inputs for the development of antifouling products and be incorporated into paints and coatings. Thus, the present study aim was synthesize antibacterial substances through chemical modification of natural substances, obtained from vegetable oils, specifically soybean oil (Glycine max (L.)). Selected substances and their variants for the synthesis were chosen based on/supported by studies that demonstrated the antifouling potential of some types of fatty acids and the efficacy of monoglycerides in combating the formation of biofilms. The following substances were synthesized: 9,10-dihydroxy octadecanoic acid; 9,10-dihydroxy octadecanoate; 9- octadecenoate 2,3-dihydroxypropanoyl; 2,3-dihydroxypropanoyl dodecanoate and 9,10-dihydroxy octadecanoate 2,3-dihydroxypropanoyl. For the synthesis of the substances, neutralization reactions using a catalyst base as well as esterification reactions with a polyalcohol (glycerol) and/or hydroxylation reactions by epoxidation were performed. To assess the antimicrobial activity, a rapid antibiogram assay was developed to observe the bacterium Pseudomonas aeruginosa UCP0992 growth obtained from the Cultures Collection of Catholic University of Pernambuco – UNICAP, Brazil. The microorganism Pseudomonas aeruginosa used in this study is reported as a pioneer in the formation of resistant biofilms. Pseudomonas aeruginosa UCP0992 was seeded in Petri dishes containing medium LB then, antibiogram disks (Ø = 6 mm) each containing the synthesized substances to be tested were transferred to the plates and arranged in equidistant positions. Plates were incubated in an oven at 30 °C and the presence or absence of halos around each disc was verified after 24h, indicating whether or not the inhibition occurred. Any halo produced, regardless of its diameter, was considered as inhibition. All synthesized substances showed inhibition halo indicating potential use for application in the microorganisms inhibition and therefore the biofilm removal.