Evaluación preliminar de la diversidad bacteriana de muestras de sedimento superficial de Muelle Storni, Puerto Madryn

JP RIVA MERCADAL; MC ESTÉVEZ; M FERRERO; H DIONISI

La Plata

Congreso; 2do Congreso Argentino de Microbiología General (SAMIGE); 2005

SAMIGE

  Recent advances in molecular biology techniques have permitted to focus in non-depending culture bacteria studies. So, the knowledge of microbial diversity has increased because of the possibility to identify most of the microorganisms present in the environment. Poorly water-soluble hydrocarbons end up as weathered material sorbed onto coastal sediments (1), representing a dangerous source of toxic and pollutant compounds for surrounding areas; being, also, an important reservoir of microorganisms capable of degrading PAHs. Numerous researchers have studied the use of marine bacteria for the biodegradation of hydrocarbons in seawater (2,3) In this work, we approached the bacterial diversity present in upper marine sediments from the coast of Muelle Almirante Storni, at Puerto Madryn. Sediment samples have been used as inoculum for growth of heterotrophic culturable bacteria at 25, 15 y 8 ºC. Two different complex media were selected for bacterial growth. One of this consisted in a modification of the R2A medium by adding 3% NaCl and adjusting pH in 7.6 with NaOH.  The other one was designed as a synthetic marine medium supplemented with 10% YPD (Nut JP). Determinations of CFU g-1 of sediment samples were made onto dish plates containing both media solidified with 1.5 % of agar and incubated at 25, 20 y 4 ºC. All bacteria counts were between 9.0 x 104 y 7.5 x 105 CFU g-1 of sediment. The higher values were observed in Medio Nutritivo JP. The evaluation of the different culture temperatures at the same medium, we found that in R2A modified, bacteria count observed at 4 ºC increased 100 and 200 % when plates were incubated at 20 and 25 ºC; while at the second medium tested, at 25 and 20 ºC we found almost 3-fold higher bacteria count than at 4 ºC. Otherwise, to study the microbial diversity obtained at the different culture conditions and those obtained directly from the sediment samples, DNA fragments amplified by PCR were separated in a poliacrylamide (PA) gel with denaturing gradient (DGGE). This technique was introduced to the molecular microbial ecology to analyze the genetic diversity of bacterial populations.