Ana Belén Segarra Robles

Biomass production and detoxification of wastewaters from the olive oil industry by strains of Penicillium isolated from wastewater disposal ponds

Olive mill wastewater (OMW) usually has to be diluted before biological treatment. In the present work seven strains of Penicillium isolated from OMW disposal ponds were tested for biomass production and biodegradation of undiluted OMW. Best results were obtained by using strain P4, which formed 21.50 g (dry weight) of biomass per litre of undiluted wastewater after 20 days of cultivation. This and other strains also carried out an outstanding reduction of the chemical oxygen demand (COD) and the phenolic content of OMW, as well as a pH raise. The process could be accelerated by agitation. OMW fermented with Penicillium P4 was devoid of its initial antibacterial activity against Bacillus megaterium ATCC 25848.

Phenol-oxidase (laccase) activity in strains of the hyphomycete Chalara paradoxa isolated from olive mill wastewater disposal ponds.

Production of laccase activity by nine strains of Chalara paradoxa isolated from olive mill wastewater disposal ponds were studied. Enzyme extracts obtained from cultured broths by adsorption on hydroxyapatite showed a single band of laccase activity on ABTS after polyacrylamide gel electrophoresis (PAGE). They showed small mobility differences, with molecular masses of 67 to 68 kDa. Enzymes from the different strains oxidized a variety of phenolic and non-phenolic substances, and they could be divided into two groups according to their relative activities on substrates. All laccases showed a dual pH dependence of activity, with a maximum in the range of pH 3.0 to 4.5 for ABTS, o-dianisidine and 2,6-dimethoxyphenol, and pH 6.0 (Group 1) or pH 6.5 (Group 2) for syringaldazine and other substrates. Optimal temperatures were in the range of 10 to 28 degrees C for two strains (maximum at 10 degrees C) and 10 to 37 degrees C for the rest. The different enzymes were partially inactivated by heating at 60 degrees C and totally inactivated at 70 degrees C. Laccases were stable in a pH range of 3.0 to 9.0 (except for strain 36A, which was partially inactivated at pH 3.0), but became inactivated at pH 2.0. Altogether these data suggest that Ch. paradoxa strains produce different laccase isoenzymes.

A study on the microbiota from olive-mill wastewater (OMW) disposal lagoons, with emphasis on filamentous fungi and their biodegradative potential.

The microbial composition of olive mill wastewater (OMW) from four disposal ponds has been studied. Such OMW samples contained a variable (but high) number of bacteria, yeasts and molds. Among the latest, members of twelve different genera (Acremonium, Alternaria, Aspergillus, Chalara, Fusarium, Lecytophora, Paecilomyces, Penicillium, Phoma, Phycomyces, Rhinocladiella and Scopulariopsis) were found. Members of five genera (Chalara, Fusarium, Paecilomyces, Penicillium and Scopulariopsis) were widely distributed, and they were able to grow efficiently in undiluted OMW as a sole source of nutrients. Strains of Fusarium, Paecilomyces, Penicillium and Scopulariopsis showed a marked capacity for OMW detoxification, depleting its antibacterial activity almost completely.

Biodegradation of olive mill wastewaters (OMW) by strains of Scopulariopsis spp. isolated from OMW‐contaminated habitats

Six strains of Scopulariopsis spp. isolated from olive mill wastewater (OMW) disposal ponds were tested for biodegradation of OMW. When growing on undiluted OMW, all strains produced relatively high amounts of biomass [from 19 to 32g (dry weight)/l], and conducted variable reductions of the chemical oxygen demand (34–54%), total phenols (41–71% and pigmentation (8–28%) of the effluent. Best results were obtained by cultivation of strain SC3 for 18 days without agitation or 10 days with agitation. This strain showed a biphasic growth, using the available carbohydrates during the first phase. Degradation of phenolic compounds and OMW decolourization occurred preferentially during the second phase of growth.