Gas chromatographic-mass spectrometric study of the degradation of phenolic compounds in wastewater olive oil by Azotobacter Chroococcum

Biodegradation of 2-ethylhexyl-4-methoxycinnamate in river sediments and its impact on microbial communities

Numerous studies have evaluated the toxicity and endocrine disrupting properties of organic UV filters for aquatic organisms, but little is known about their biodegradation in river sediments and their impact on microorganisms. We have set up the sterile and microbiological systems in the laboratory, adding 2-ethylhexyl-4-methoxycinnamate (EHMC), one of organic UV filters included in the list of high yield chemicals, at concentrations of 2, 20 and 200 μg/L, and characterized the microbial community composition and diversity in sediments. Monitoring of EHMC degradation within 30 days revealed that the half-life in the microbial system (3.49 days) was much shorter than that in the sterile system (7.55 days). Two potential degradation products, 4-mercaptobenzoic acid and 3-methoxyphenol were identified in the microbial system. Furthermore, high-throughput 16s and 18s rRNA gene sequencing showed that Proteobacteria dominated the sediment bacterial assemblages followed by Chloroflexi, Acidobacteria, Bacteroidetes and Nitrospirae; Eukaryota_uncultured fungus dominated the sediment fungal assemblages. Correlation analysis demonstrated that two bacterium genera (Anaerolineaceae_uncultured and Burkholderiaceae_uncultured) were significantly correlated with the biodegradation of EHMC. These results illustrate the biodegradability of EHMC in river sediments and its potential impact on microbial communities, which can provide useful information for eliminating the pollution of organic UV filters in natural river systems and assessing their potential ecological risks.

Olive Mill Waste Extracts: Polyphenols Content, Antioxidant, and Antimicrobial Activities

Natural polyphenols extracts have been usually associated with great bioactive properties. In this work, we investigated in vitro antioxidant and antimicrobial potential of the phenolic olive mill wastewater extracts (OWWE) and the olive cake extracts (OCE). Using the Folin Ciocalteux method, OWWE contained higher total phenol content compared to OCE (8.90 ± 0.728 g/L versus 0.95 ± 0.017 mg/g). The phenolic compounds identification was carried out with a performance liquid chromatograph coupled to tandem mass spectrometry equipment (HPLC-ESI-MS). With this method, a list of polyphenols from OWWE and OCE was obtained. The antioxidant activity was measured in aqueous (DPPH) and emulsion (BCBT) systems. Using the DPPH assay, the results show that OWWE was more active than OCE and interestingly the extracts originating from mountainous areas were more active than those produced from plain areas (EC₅₀ = 12.1 ± 5.6 μg/mL; EC₅₀ = 157.7 ± 34.9 μg/mL, resp.). However, when the antioxidant activity was reversed in the BCBT, OCE produced from plain area was more potent than mountainous OCE. Testing by the gel diffusion assay, all the tested extracts have showed significant spectrum antibacterial activity against Staphylococcus aureus, whereas the biophenols extracts showed more limited activity against Escherichia coli and Streptococcus faecalis.

Solid state fermentation of olive mill residues by wood- and dung-dwelling Agaricomycetes: effects on peroxidase production, biomass development and phenol phytotoxicity

The in vivo conversion of dry olive mill residue (DOR) by wood- and dung-dwelling fungi - Auricularia auricula-judae, Bjerkandera adusta and Coprinellus radians - increases peroxidase secretion up to 3.2-3.5-fold (∼1.3, 3.5 and 7.0 Ug(-1) DOR for dye-decolorizing peroxidase, manganese peroxidase and aromatic peroxygenases, respectively). The incubation of DOR with these fungi produced a sharp decrease in total phenolic content (100% within 4 wk), a reduction in phytotoxicity as well as a certain degree of plant growth caused by the stimulating effect of fungal-treated DOR. These findings correlate with a characteristic shift in the fragmentation pattern of water-soluble aromatics (detected at 280 nm) from low (0.2, 1.5 and 2.2 kDa, respectively) to high molecular mass (35 to >200 kDa), which demonstrates the presence of a polymerization process. Phenol-rich agricultural residues are a useful tool for enzyme expression and production studies of peroxidase-producing Agaricomycetes which could make DOR a valuable organic fertilizer.

High yields of hydrogen production induced by meta-substituted dichlorophenols biodegradation from the green alga Scenedesmus obliquus

Hydrogen is a highly promising energy source with important social and economic implications. The ability of green algae to produce photosynthetic hydrogen under anaerobic conditions has been known for years. However, until today the yield of production has been very low, limiting an industrial scale use. In the present paper, 73 years after the first report on H(2)-production from green algae, we present a combinational biological system where the biodegradation procedure of one meta-substituted dichlorophenol (m-dcp) is the key element for maintaining continuous and high rate H(2)-production (>100 times higher than previously reported) in chloroplasts and mitochondria of the green alga Scenedesmus obliquus. In particular, we report that reduced m-dcps (biodegradation intermediates) mimic endogenous electron and proton carriers in chloroplasts and mitochondria, inhibit Photosystem II (PSII) activity (and therefore O(2) production) and enhance Photosystem I (PSI) and hydrogenase activity. In addition, we show that there are some indications for hydrogen production from sources other than chloroplasts in Scenedesmus obliquus. The regulation of these multistage and highly evolved redox pathways leads to high yields of hydrogen production and paves the way for an efficient application to industrial scale use, utilizing simple energy sources and one meta-substituted dichlorophenol as regulating elements.

Defence response of tomato seedlings to oxidative stress induced by phenolic compounds from dry olive mill residue

ADOR is an aqueous extract obtained from the dry olive mill residue (DOR) which contains the majority of its soluble phenolic compounds, which are responsible for its phytotoxic properties. Some studies have shown that ADOR negatively affects seed germination. However, to date, few studies have been carried out on the effect of ADOR on the oxidative stress of the plant. It is well known that saprobe fungi can detoxify these phenolic compounds and reduce the potential negative effects of ADOR on plants. To gain a better understanding of the phytotoxic effects and oxidative stress caused by this residue, tomato seeds were germinated in the presence of ADOR, treated and untreated with Coriolopsis rigida, Trametes versicolor, Pycnoporus cinnabarinus and Penicillium chrysogenum-10 saprobe fungi. ADOR sharply reduced tomato seed germination and also generated high levels of malondialdehyde (MDA), O(2)(-) and H(2)O(2). However, bioremediated ADOR did not negatively affect germination and reduced MDA, O(2)(-) and H(2)O(2) content in different ways depending on the fungus used. In addition, the induced defense response was studied by analyzing the activity of both antioxidant enzymes (superoxide dismutase (SOD), catalase, ascorbate peroxidasa, glutathione reductase (GR), peroxidases and coniferil alcohol peroxidasa) and detoxification enzymes (glutathione-S-transferase (GST)). Our findings suggest that, because ADOR is capable of inducing oxidative stress, tomato seedlings trigger a defense response through SOD, GR, and GST activity and through antioxidant and lignification processes. On the other hand, the bioremediation of ADOR plays an important role in counteracting the oxidative stress induced by the untreated residue.

Microbial community changes in aquifer sediment microcosm for anaerobic anthracene biodegradation under methanogenic condition

The widespread distribution of polycyclic aromatic hydrocarbons (PAHs) in groundwater has become an important environmental issue. Knowledge of microbial community changes could aid in identification of particular microorganisms that are capable of degrading PAHs in contaminated aquifers. Therefore, 16S rRNA gene clone library analysis was used to identify the archaeal and bacterial communities in an aquifer sediment microcosm used for anaerobic anthracene degradation under methanogenic conditions. A remarkable shift of the archaeal community structure occurred after anaerobic anthracene degradation, but the types of the abundant bacterial phyla did not change. However, a decrease of both archaeal and bacterial diversity was observed. Bacterial genera Bacillus, Rhodococcus and Herbaspirillum might have links with anaerobic anthracene degradation, suggesting a role of microbial consortia. This work might add some new information for understanding the mechanism of PAH degradation under methanogenic conditions.

The effect of metal salts on the decomposition of sweet sorghum bagasse in flow-through liquid hot water

The impact of the metal salts NaCl, KCl, CaCl(2), MgCl(2), FeCl(3), FeCl(2), and CuCl(2), particularly the latter, on the decomposition of hemicellulose and lignin from sweet sorghum bagasse in liquid hot water pretreatment processing was studied in an attempt to enhance the recovery of sugars. Transition metal chlorides significantly enhanced the hemicellulose removal compared to the alkaline earth metal chlorides and alkaline metal chlorides, contributing to the formation of a saccharide-metal cation intermediate complex. FeCl(2) greatly increased xylose degradation and about 60% xylan was converted into non-saccharide products. In contrast, an excellent total and monomeric xylose recovery was obtained after the CuCl(2) pretreatment. Most of the lignin was deposited on the surface of the residual solid with droplet morphologies after this pretreatment, and about 20% was degraded into monomeric products. The total recovery of sugars from sweet sorghum bagasse with 0.1% CuCl(2) solution pretreatment and 48 h enzymatic digestibility, reached 90.4%, which is superior to the recovery using hot water pretreatment only.

Metabolic characterization of a strain (BM90) of Delftia tsuruhatensis showing highly diversified capacity to degrade low molecular weight phenols

A novel bacterium, strain BM90, previously isolated from Tyrrhenian Sea, was metabolically characterized testing its ability to use 95 different carbon sources by the Biolog system. The bacterium showed a broad capacity to use fatty-, organic- and amino-acids; on the contrary, its ability to use carbohydrates was extremely scarce. Strain BM90 was identified and affiliated to Delftia tsuruhatensis by molecular techniques based on 16S rRNA gene sequencing. D. tsuruhatensis BM90, cultivated in shaken cultures, was able to grow on various phenolic compounds and to remove them from its cultural broth. The phenols used, chosen for their presence in industrial or agro-industrial effluents, were grouped on the base of their chemical characteristics. These included benzoic acid derivatives, cinnamic acid derivatives, phenolic aldehyde derivatives, acetic acid derivatives and other phenolic compounds such as catechol and p-hydroxyphenylpropionic acid. When all the compounds (24) were gathered in the same medium (total concentration: 500 mg/l), BM90 caused the complete depletion of 18 phenols and the partial removal of two others. Only four phenolic compounds were not removed. Flow cytometry studies were carried out to understand the physiological state of BM90 cells in presence of the above phenols in various conditions. At the concentrations tested, a certain toxic effect was exerted only by the four compounds that were not metabolized by the bacterium.

In vitro physiological responses of Fusarium oxysporum f. sp. niveum to exogenously applied syringic acid

Plant-microbe interactions are often accompanied by allelochemicals, such as syringic acid, released from the host plant. To explore the role of phenolic acids released from crop host plants in response to pathogen invasion, we examined the allelopathic effect of an artificially applied syringic acid on Fusarium oxysporum f. sp. niveum. We demonstrated that the growth and the conidial germination rate of F. oxysporum f. sp. niveum were stimulated at lower concentrations of syringic acid, though inhibited by higher dosage compared with control. The yield of fungus mycotoxin was increased from 60.9% to 561.5%. We conclude that syringic acid can be considered as a allelochemical inducer, stimulating the relative virulence factors of invading pathogens.