ANTIMICROBIAL ACTIVITY OF SILVER NANOPARTICLES SYNTHESIZED USING AQUEOUS EXTRACT OF ?Bothriochloa laguroides?

PAEZ PL; TORANZO A; DALMASSO PR; VILLEGAS L; DELFINI C

Tucumán

Congreso; XII CONGRESO ARGENTINO DE MICROBIOLOGIA - SAMIGE 2017; 2017

SAMIGE

The continuing appearance of antibiotic resistance in pathogenic and opportunistic microorganisms obliges the scientific community to constantly develop new drugs and drug targets.In the current scenario, nanotechnology offers opportunities to reexplore the biological properties of already known antimicrobial materials by manipulating their size to alter the effect.Due to nanoparticles have demonstrated antimicrobial activity, the development of novel applications in this field makes them an attractive alternative to antibiotics.The aim of the present work was to determine the effect of silver nanoparticles (AgNPs) against four bacterial species and eight phytopathogenic fungi. For this, a simple and economic method of biosynthesis of AgNPs was used employing an aqueous leaf extract of Bothriochloa laguroides (known in Argentina as ?cola de zorro?) as reducing and stabilizing agentand AgNO3. In vitro susceptibility of the bacteria and phytopathogenic fungi to the biosynthesized AgNPs was evaluated using agar diffusion technique. The agar plate surface was inoculated by spreading a volume (100 µL) of the microbial inoculum over the entire agar surface. Then, four holes with a diameter of 6 mm were punched aseptically. Into the hole was placed:i-100 µL of water as negative control, ii- 100 µL AgNO3 solution,iii- 100 µL of the plant extract and iv- 100 µL of the AgNPs. Potato dextrose agar and trypticase soy agar were used for fungus and bacteria growth respectively. Then, agar plates were incubated at under suitable conditions depending the test microorganism (37 ºC and 28 ºC for bacteria and fungi, respectively).The results obtained showed an antimicrobial effect of AgNPs on the four tested bacterial species and on six of the eight fungi, showing greater inhibition in bacteria than in phytopatogenic fungi, for which it was decided to continue the following tests with the bacteria. The determination of minimum inhibitory concentration (MIC) was carried out through the standard tube dilution method on Mueller Hinton broth and using resazurin as indicator of cell viability. The minimum bactericidal concentration (MBC) was determined after 18 hours of incubation. The zone of inhibition varied in range of 4 to 6.5 mm for bacteria and in range of 2 to 4.25 mm for fungi with AgNPs concentration, while AgNO3 solution and aqueous extracts of B. laguroides did not showed antimicrobial activity, MIC and MBC results showed the following order of sensitivity: Staphylococcusaureus ATCC 43300