Potential biosurfactant producing endophytic and epiphytic fungi, isolated from macrophytes in the Negro River in Manaus, Amazonas, Brazil

Endophytic and epiphytic fungi isolated from Eichhornia crassipes (Mart.) Solms and Cyperus ligularis L., macrophytes collected from oil-contaminated waters, were studied to assess their potential for producing biosurfactants; the most promising ones were identified by means of the rDNA region sequencing. In the selection, in the hydrocarbonate biodegradation activity, 2.6-indophenol (DCPIP) in oil-added Bushnell-Haas (BH) medium was the indicator used. The following tests were performed to ascertain the biosurfactant, bioemulsifier activity: emulsification measurement, drop-collapse, surface tension and production slope. Of the twenty fungi isolated, six promoted DCPIP discoloration. The isolate (S31) Phoma sp. showed emulsification of diesel (1.5 cm or 52%) and reduction of the surface tension of 51.03 mN/m water identified as Phoma sp. The other five fungi were identified as Rhizopus oryzae (S24), Fusarium sp. (S32, S33, S42, S46), presenting potential for biodegradation of hydrocarbons, as well. New studies on Phoma sp. (S31), including its cultivation in different carbon sources will be necessary to improve the production of secondary compounds involved in surface tension bioemulsification and reduction.Keywords: Bioremediation, bioemulsifiers, Eichhornia, Cyperus, oil, diese

Biodegradation of the fungicide carbendazim by bacteria from Coriandrum sativum L. rhizosphere

 The biocidal agrochemicals commonly used in agriculture can remain in the soil, affecting the environmental conditions and causing serious risks to health. Knowing that soil microorganisms, especially those from the rhizosphere, can degrade environmental xenobiotics, it was evaluated the potential of bacteria isolated from Coriandrum sativum L. rhizosphere to biodegrade carbendazim (MBC), a fungicide extensively used by agriculturists from rural farming communities in Manaus, Amazonas. Cultures carried out in medium containing carbendazim as a sole carbon source enabled the isolation of 80 bacteria, in the established conditions. Assays to determine degradation potential allowed the selection of the two elite isolates identified as Stenotrophomonas sp. and Ochrobactrum sp. Quantitative assays with each strain individually or in consortium, were carried out using minimal salt medium added with carbendazim (250 µg mL-1) and incubated at 30°C, under agitation (125 rpm) for 21 days. Samples used in the biodegradation test were HPLC analyzed for final fungicide quantitation. The Stenotrophomonas sp. strain was more efficient (68.9%) to degrade carbendazim and showed no toxicity in tests with Artemia salina.