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Congo red is one of the best known and used azo dyes which has two azo bonds (-N=N-) chromophore in its molecular structure. Its structural stability makes it highly toxic and resistant to biodegradation. The objective of this study was to assess the congo red biodegradation and detoxification by Aspergillus niger. The effects of pH, initial dye concentration, temperature, and shaking speed on the decolorization rate and enzymes production were studied. The maximum decolorization was correlated with lignin peroxidase and manganese peroxidase production. Above 97% were obtained when 2 g mycelia were incubated at pH 5, in presence of 200 mg/L of dye during 6 days at 28°C and under 120 to 150 rpm shaking speed. The degraded metabolites were characterized by using LC-MS/MS analyses and the biodegradation mechanism was also studied. Congo red bioconversion formed degradation metabolites mainly by peroxidases activities, i.e., the sodium naphthalene sulfonate (m/z = 227) and the cycloheptadienylium (m/z = 91). Phytotoxicity and microtoxicity tests confirmed that degradation metabolites were less toxic than original dye.

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Kombucha is a beverage that is prepared by fermenting sweetened black tea using a tea fungus, which is a symbiotic culture of acetic acid bacteria and yeasts. In the present study, cactus pear juice was used as a substrate for kombucha fermentation in order to develop a new beverage with enhanced nutritional properties. Changes in chemical and microbiological parameters of the fermented juice were determined during fermentation. The growth of microflora induced a reduction in pH from 5.1 to 3.5 and a 23 % increase in total phenol content after 6 days of fermentation. The antioxidant potential of the beverage was also improved, reaching 81 % and 65 % as determined, respectively, by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. The improved antioxidant capacity was attributed to betalains and to certain metabolic products formed during the fermentation process. Furthermore, the fermented juice showed antimicrobial activity against the tested Gram-positive (Staphylococcus aureus ATCC 6538, Bacillus cereus ATCC 11778, Staphylococcus epidermidis ATCC 12228 and Enterococcus faecalis ATCC 10541) and Gram-negative bacteria (Escherichia coli ATCC 10536, Klebsiella pneumoniae ATCC 10031, and Pseudomonas aeruginosa ATCC 9027), which was attributed to its acetic acid content. Sensory evaluation of fresh juice and juice after 6 and 12 days of fermentation by a taste panel showed high acceptability of the juice after the first 6 days of fermentation, as the cactus pear juice taste qualities were still present, without the higher acidity that some panelists found unacceptable after longer fermentation.

Aim: Decolourization of black olive mill wastewaters (OMW) by depolymerization of phenolic compounds by Geotrichum candidum. Methods and Results: Our results show that G. candidum is able to grow on black OMW supplemented with carbon source and nitrogen. The Geotrichum growth decreased the pH and induced a 49% of colour removal when the black OMW was supplemented with glycerol and diammonium tartrate (20 mM M ammonium). An improvement of 10% of colour removal was observed when the culture was supplemented with veratryl alcohol. The decolourization was inhibited with glutamate as nitrogen source. Conclusion: Our results suggest the potential use of G. candidum in black OMW decolourization and support the concept that lignin peroxidase (LiP) of G. candidum is involved in the depolymerization of phenolic compounds. Significance and Impact of the Study: This is the first report of LiP production by G. candidum on OMW.

Aspergillus niger has been tested in a discontinuous process for the pretreatment of fresh green Table Olive Processing Waste waters (TOPW). The influence of seven factors like incubation time, initial pH, dilution, glucose, agitation, (NH 4 ) 2 SO 4 and inoculum size on decolorization was screened by employing a fractional factorial design 2 7-4 . Through factorial plots and analysis of variance, it was found that only glucose and agitation affected the decolorization. Further studies were carried out to adjust the level of determinant factors. Results showed that color removal (62%) was optimum at 150 rpm and 3 g/l glucose. HPLC and FTIR analysis of the treated TOPW suggested that the decolorization occurs through biosorption and biodegradation. Tannase and lignin peroxidase were detected in the cultures. However, only tannase is responsible for the color removal of the TOPW because lignin peroxidase is produced at a low level. Data are reported as mean ± standard deviation of results carried out in triplicate Characteristics

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