Aislamiento y caracterización de bacterias metanogénicas de sedimentos urbanos del estero el macho mediante un enfoque de ecosalud.

Abstract

Methanogenic bacteria are methane-producing microorganisms, which need anaerobic conditions for their energy metabolism, their survival depends on the acetoclastic, methylotropic or hydrogenotrophic pathways, they use carbon dioxide, methyl and acetate substrates that are essential for the anoxic codigestion of the organic material. The increase in population in Machala City has been a major factor in the high levels of environmental pollution. The continuous discharges of wastewater, the overproduction of organic waste, the waste from the banana sector and the settlement of its surroundings have caused this Estero to be integrated with dangerous organic and inorganic compounds and a large bacterial load that constitutes a body of water with muds activated. The impact of this situation is evidenced when these toxic waste reach the oceans causing damage to ecosystems and are harmful to the health of the population. Biotechnology is a tool in the treatment of active sediments, a process in which methanogenic bacteria are used to stabilize contaminated sludge by reducing pathogens, bad odors and putrefaction conditions. The objective of this research work was to isolate and characterize methanogenic bacteria by means of microbiological methods in sediment samples to evaluate the anaerobic methane oxidation potential in El Macho Estuary in Machala City. The methanogenic bacteria of the genus Methanococcus and Methanobacterium were isolated by means of the culture media Stadtman-Barker and Barker Taha respectively. Seeding was carried out in solid and liquid medium and viable cells were quantified by establishing methods for counting CFU (Colony Forming Units) in plaque and by the NMP method (most probable number). The phenotypic identification was performed with Gram stain and by microscopic observation the morphological characteristics of each species was determined. In addition, biochemical tests were applied compared with reference values of the strains Methanococcus Deltae and Methanobacterium Ruminantium, in which TSI agar (triple sugar iron), medium SIM (Sulfur, indole and motility), Simmons citrate and urea media were used. The established biochemical reactions were: fermentation of glucose, sucrose and lactose, gas production, presence of hydrogen sulfide, oxidation of tryptophan, mobility, pH changes, enzymatic reactions and changes of coloration in the media. On the other hand, systems of bioreactors with lignocellulosic organic matter (pea skin) plus isolated strains were assembled, in which biogas was generated, after each week of anaerobic codigestion the measurement of methane gas and carbon dioxide was made by chromatography gas. The results show the growth of bacteria of the genus Methanococcus and Methanobacterium, and it was identified that the morphological domains of these bacteria are streptobacilli and cetaceans respectively. It was also defined that these bacteria ferment sugars, generate hydrogen sulfide gas, are mobile and produce turbidity in the culture media. The bioreactor that produced the greatest amount of methane was the one is constituted by both strains of methanogens generating a 9% methane gas to the three weeks of anaerobic digestion. The bacteria of the genus Methanobacterium were in greater quantity than those of the genus Methanococcus. in solid media and broths, as well as produce more biogas.