Federico Federici

Role of Autochthonous Filamentous Fungi in Bioremediation of a Soil Historically Contaminated with Aromatic Hydrocarbons

ABSTRACT Nine fungal strains isolated from an aged and heavily contaminated soil were identified and screened to assess their degradative potential. Among them, Allescheriella sp. strain DABAC 1, Stachybotrys sp. strain DABAC 3, and Phlebia sp. strain DABAC 9 were selected for remediation trials on the basis of Poly R-478 decolorization associated with lignin-modifying enzyme (LME) production. These autochthonous fungi were tested for the abilities to grow under nonsterile conditions and to degrade various aromatic hydrocarbons in the same contaminated soil. After 30 days, fungal colonization was clearly visible and was confirmed by ergosterol determination. In spite of subalkaline pH conditions and the presence of heavy metals, the autochthonous fungi produced laccase and Mn and lignin peroxidases. No LME activities were detected in control microcosms. All of the isolates led to a marked removal of naphthalene, dichloroaniline isomers, o-hydroxybiphenyl, and 1,1′-binaphthalene. Stachybotrys sp. strain DABAC 3 was the most effective isolate due to its ability to partially deplete the predominant contaminants 9,10-anthracenedione and 7H-benz[DE]anthracen-7-one. A release of chloride ions was observed in soil treated with either Allescheriella sp. strain DABAC 1 or Stachybotrys sp. strain DABAC 3, suggesting the occurrence of oxidative dehalogenation. The autochthonous fungi led to a significant decrease in soil toxicity, as assessed by both the Lepidium sativum L. germination test and the Collembola mortality test.

Submerged and solid-state production of laccase and Mn-peroxidase by Panus tigrinus on olive mill wastewater-based media.

The possible use of olive-mill wastewater (OMW) as a growth medium for the production of extracellular laccase and manganese peroxidase (MnP) from the white-rot fungus Panus tigrinus (P. tigrinus) CBS 577.79 was studied using a properly formulated OMW-based medium (2-fold diluted OMW supplemented with 0.5% sucrose and 0.1% yeast extract) either in a stirred-tank or an air-lift reactor. Solid-state fermentation (SSF) was also performed in a rotary drum reactor using maize stalks moistened with the OMW-based medium. Highest levels of laccase and manganese peroxidase activity were obtained in the stirred-tank reactor (4600+/-98 U l(-1) on day 13) and in the air-lift reactor (410+/-22 on day 7), respectively. Based on total enzyme activities, SSF appears to be more suitable than LSF but the latter exhibits better volumetric productivities.

Immobilized cell technology applied in solubilization of insoluble inorganic (rock) phosphates and P plant acquisition

This paper reviews current knowledge of the production of organic acids by immobilized microorganisms with a simultaneous solubilization of rock phosphate in fermentation and soil conditions. The most widely applied methods are based on the passive immobilization in preformed porous carriers and entrapment of the microbial cells in natural gels. In general, immobilized systems show higher acid producing and rock phosphate solubilizing activity than freely suspended cells. The potential of gel-entrapped P-solubilizers and mycorrhizal fungi as microbial soil inoculants is also pointed out. Some advantages and constraints of using immobilized cells are discussed and a special emphasis on further research is given.

Aerobic treatment of winery wastewater using a jet-loop activated sludge reactor

A jet-loop activated sludge reactor (JLR) of 15 dm3 working volume was used for the aerobic treatment of winery wastewater (WW). The reactor was operated continuously for more than 12 months using WW from different wineries and collected in different periods of the year with CODs that ranged between 0.8 and 12.8 kg m−3. Loading rates were from 0.4 to 5.9 kg-COD m−3 day−1 with hydraulic retention times that varied from 2.1 to 4.4 days. The system reacted well to sudden variations of loading: the COD removal efficiency was always higher than 90% with an organic load of the final effluents that ranged between 0.11 and 0.3 kg-COD m−3. After 185 days of continuous operation, the residential microbial population, of either the mixed liquor or the biofilm formed on the reactors inner wall, was studied and characterized at the genus level. Most isolates belong to the genus Pseudomonas and the yeast Saccharomyces cerevisiae.

Yeast flora of grape berries during ripening

The yeast flora associated with the surface of grapes during ripening was studied with regard to different sectors of the grape skin and the position in the bunch by means of traditional as well as more vigorous preisolation and precounting treatments. The yeast number per square centimeter of skin increases with ripening and is highest in the area immediately surrounding the stem. The cluster sector closer to the peduncle seems to constitute a favorable substrate for yeasts, hosting a resident flora about 10 and 100 times higher than the central and lower parts of the bunch, respectively.Kloeckera apiculata was the normal resident species of grapes regardless of the sector or the ripening period, and constitutes the fermenting flora of mature grapes. The ecological implications of the results of this survey are discussed.

Production and structural characterization of the exopolysaccharide of the Antarctic fungus Phoma herbarum CCFEE 5080

The filamentous fungus Phoma herbarum CCFEE 5080 isolated from continental Antarctica soil was tested for exopolysaccharide (EPS) production. The fungus grew and produced EPS (up to 13.6 g/l) on a variety of carbon sources among which sorbitol was best, particularly at the concentration of 60 g/l. EPS production was maximum when the nitrogen source was NaNO3 (3 g/l) and the incubation temperature was 28 degrees C. The polysaccharide was purified by repeated precipitation in ethanol and gel filtration and characterized as a homopolymer of glucose having a molecular weight of 7.412 x 10(6); structural analysis indicated the presence of beta-1,3 and beta-1,6 linkages only. After repeated freezing and thawing of the fungal biomass in the presence of EPS, the mycelial growth was much higher than that observed after freezing in the absence of EPS and the difference increased with the number of freeze-thaw cycles. It is hypothesized that the adaptation of P. herbarum CCFEE 5080 to the Antarctic soil microclimatic conditions, characterized by low temperature, high thermal fluctuations and repeated freeze-thaw cycles, might be related to the EPS production ability.

High-rate aerobic treatment of winery wastewater using bioreactors with free and immobilized activated sludge.

COD (chemical oxygen demand) removal rate and efficiency of winery wastewater (WW) aerobic treatments were evaluated in an air-bubble column bioreactor using self-adapted microbial populations either free or immobilized on polyurethane particles and in a packed-bed bioreactor immobilized on Raschig rings. The bioreactors were fed continuously for up to 12 months using WW of different origins and with different pollution loads (COD range, 0.8-11.0 kg.m(-3)): the maximum loading rate was approx. 8.8 kg-COD m(-3).d(-1). The highest COD removal rate (6.6 kg.m(-3).d(-1)) was obtained with free activated sludge in the bubble column bioreactor; treatment efficiency and hydraulic retention time were >90% and approx. 0.8 d, respectively. The microbial populations in the three reactors were characterized.

Reuse of microbially treated olive mill wastewater as fertiliser for wheat (Triticum durum Desf.).

Free cells of Aspergillus niger were grown on olive mill wastewater (OMW) supplemented with rock phosphate (RP) in an air-lift bioreactor in batch and repeated-batch processes. The fungus grew well and reduced the chemical oxygen demand of the waste by 35% and 64% in the batch and repeated-batch (fourth batch) processes, respectively. Total sugar content was consistently reduced (ca. 60%) in both processes while reduction of total phenols was minimal. RP was solubilised and maximum soluble P was 0.63 and 0.75 gl(-1) in the batch and repeated-batch (third batch), respectively. Several types of OMW+/-RP, microbially-treated or not, were tested in a greenhouse for their fertilising ability on a soil-wheat (Triticum durum Desf.) model system. Beneficial effects were highest using OMW treated by the repeated-batch process. The treated plants showed an increase in seed biomass, spike number, and kernel weight. Harvest index was highest (0.49+/-0.04) after treatment with OMW from the repeated-batch process.

Rock phosphate solubilization with gluconic acid produced by immobilized Penicillium variabile P16

Penicillium variabile P16 immobilized on polyurethane sponge produced gluconic acid in presence of rock phosphate, the latter being simultaneously solubilized during five repeated batches. A total production of 42, 60, and 90 g gluconic acid/l was obtained for 3, 7, and 14 g rock phosphate/l, respectively. Accordingly, soluble phosphorus concentration increased with gluconic acid production, reaching a maximum of 350 mg/l at the 3d batch in medium supplemented with 14 g rock phosphate/l.

Application of encapsulated Penicillium variabile P16 in solubilization of rock phosphate

Abstract Penicicllium variabile P16, encapsulated in agar or calcium alginate, produced gluconic acid in repeated batch shake-flask cultures. Agar-encapsulated mycelium produced 21% more gluconic acid than Ca-alginate-encapsulated fungus, and was utilized in experiments for rock phosphate solubilization. The latter was closely related to gluconic acid production, which was affected by the presence of rock phosphate. Maximum amounts of dissolved P (0.226 gl−1 batch−1) were found at 14.0 gl−1 rock phosphate, but the solubilization efficiency was higher at 3.5 gl−1 rock phosphate. Gluconic acid productivity pattern and the degree of phosphate solubilization were not influenced by decreasing the glucose concentration in the cultivation medium from 80 to 25 gl−1. Encapsulated fungal cells systems could substitute for chemical solubilization of rock phosphate and could be applied as soil microbial inoculants.