In-situ sulphide control in the anaerobic co-digestion of residual biomass from the production of penicillin and cystine.

This study was focused on the anaerobic digestion of residual biomass from the production of penicillin and l-cystine. The biogas potential tests of individual substrates and their mixture showed good anaerobic biodegradability. The highest measured specific biogas production was 712 l/kg volatile solids (VS) for penicillin biomass and 676 l/ kg VS for cystine biomass. The biogas potential tests were performed at different inoculum-to-substrate ratios (ISR) and showed that high concentrations of nitrogen and sulphur present in residual biomass have a major impact on the anaerobic processes. The long-term operation of the laboratory anaerobic reactor showed that the mono-digestion of the penicillin biomass was stable at an OLR of 1 kg/(m3.d). When co-digestion of penicillin and cystine biomass at a ratio of 0.9:0.1 (on a VS basis) and at the same OLR was enhanced, the operation of the laboratory model turned unstable. During this phase of the operation, the course of anaerobic processes was affected by ammonia and especially sulphide inhibition. Sulphide inhibition was effectively reduced by direct dosing of FeCl2 (in-situ sulphide control), at a molar iron-to-sulphur ratio of ß = 1 (mol Fe/mol S). When suppressing sulphide inhibition, the operation of the laboratory model became stable even at a co-digestion ratio of 0.5:0.5 (VS basis). The results of this work open a new scope for future applications in the anaerobic digestion of waste biomass with high sulfur content, coming from industrial fermentation processes.

The interaction between lipids and ammoniacal nitrogen mitigates inhibition in mesophilic anaerobic digestion.

Ammoniacal nitrogen and long chain fatty acids (LCFA) are common inhibitors of the anaerobic digestion process. However, the interaction between these inhibitors has received little attention. Understanding the interaction between these inhibitors is important to optimise the operation of anaerobic digesters treating slaughterhouse waste or using fat, oil and grease (FOG) as co-substrate among others. To study the interaction between ammoniacal nitrogen and LCFA inhibition, 20 different conditions were trialled in mesophilic batch tests. Experimental conditions included 5 mixtures between slaughterhouse wastewater and LCFA (100:0, 75:25, 50:50, 20:80, 0:100 on a VS basis), each one tested at 4 different ammoniacal nitrogen concentrations (0, 1, 3, 6 gNadded·L-1). Experimental and modelling results showed that ammoniacal nitrogen inhibition was less severe in LCFA-rich mixtures, indicating that LCFA mitigated ammoniacal nitrogen inhibition to a certain extent. However, the positive interaction between inhibitors did not only depend on the LCFA concentration. A protective LCFA coat that limited the diffusion of free ammonia into the cell and/or provided a localised lower pH in the vicinity of the microbial cell could explain the experimental results. However, ammoniacal nitrogen and LCFA inhibition comprise up to 6 different but interrelated inhibitors (i.e. NH3, NH4+, LCFA, VFA, H2 and pH) and therefore the specific mechanism could not be elucidated. Nonetheless, these results suggest that LCFA do not exacerbate TAN-related inhibition and that LCFA-rich substrates can be utilised as co-substrates in mesophilic N-rich digesters.

Correction: The natural compound Jatrophone interferes with Wnt/ß-catenin signaling and inhibits proliferation and EMT in human triple-negative breast cancer.

[This corrects the article DOI: 10.1371/journal.pone.0189864.].

The natural compound Jatrophone interferes with Wnt/ß-catenin signaling and inhibits proliferation and EMT in human triple-negative breast cancer.

Metastatic breast cancer is the leading cause of worldwide cancer-related deaths among women. Triple negative breast cancers (TNBC) are highly metastatic and are devoid of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) amplification. TNBCs are unresponsive to Herceptin and/or anti-estrogen therapies and too often become highly chemoresistant when exposed to standard chemotherapy. TNBCs frequently metastasize to the lung and brain. We have previously shown that TNBCs are active for oncogenic Wnt10b/ß-catenin signaling and that WNT10B ligand and its downstream target HMGA2 are predictive of poorer outcomes and are strongly associated with chemoresistant TNBC metastatic disease. In search of new chemicals to target the oncogenic WNT10B/ß-CATENIN/HMGA2 signaling axis, the anti-proliferative activity of the diterpene Jatrophone (JA), derived from the plant Jatropha isabelli, was tested on TNBC cells. JA interfered with the WNT TOPFLASH reporter at the level between receptor complex and ß-catenin activation. JA efficacy was determined in various subtypes of TNBC conventional cell lines or in TNBC cell lines derived from TNBC PDX tumors. The differential IC50 (DCI50) responsiveness was compared among the TNBC models based on etiological-subtype and their cellular chemoresistance status. Elevated WNT10B expression also coincided with increased resistance to JA exposure in several metastatic cell lines. JA interfered with cell cycle progression, and induced loss of expression of the canonical Wnt-direct targets genes AXIN2, HMGA2, MYC, PCNA and CCND1. Mechanistically, JA reduced steady-state, non-phosphorylated (activated) ß-catenin protein levels, but not total ß-catenin levels. JA also caused the loss of expression of key EMT markers and significantly impaired wound healing in scratch assays, suggesting a direct role for JA inhibiting migration of TNBC cells. These results indicate that Jatrophone could be a powerful new chemotherapeutic agent against highly chemoresistant triple negative breast cancers by targeting the oncogenic Wnt10b/ß-catenin signaling pathway.

Anaerobic digestion of waste biomass from the production of L-cystine in suspended-growth bioreactors.

Waste biomass from the industrial production of the amino acid L-cystine contains above-average concentrations of organic pollutants and significant concentrations of nitrogen and sulfur. The specific biogas production (SBP) of waste biomass was monitored in parallel suspended-growth laboratory anaerobic bioreactors. After severe inhibition was observed, three different procedures were applied to inhibited reactor sludge to counter-attack the inhibitory effects of sulfides, respectively hydrogen sulfide: micro-aeration, dilution with water and precipitation by ferrous iron cations. The performance of bioreactors was weekly monitored. Organic loading rates (as chemical oxygen demand, COD) ranged from 1.07 to 1.97 g L(-1) d(-1). At the end of the experimentation, SBP averaged 217, 300 and 320 l kg(-1) COD with a methane content of 21%, 52% and 54%; specific sludge production averaged 133, 111 and 400 g total solids kg(-1) COD, and inhibition was 49%, 27% and 25%; for the applied procedures of micro-aeration, dilution and precipitation respectively.

Anaerobic digestion of crude glycerol as sole substrate in mixed reactor.

Utilization of crude glycerol (CG) from the biodiesel industry in the production of biogas offers a perspective of further energy generation, which may result into the drop of biodiesel costs on the developing world market. This contribution is focused on anaerobic treatment of CG as a single substrate in mixed laboratory reactors. Experiences from long-term operation of mixed reactors processing either untreated or acidulated CG are discussed. The possibility of cofermentation of washing water (WW) from biodiesel production with CG was also attempted. It was demonstrated that long-term mesophilic anaerobic treatment of CG as the only substrate is possible. Except for nitrogen, and possibly phosphorus, the addition of other nutrients is unnecessary. Processing of both non-acidulated and acidulated CG in laboratory mixed reactors inoculated with suspended sludge resulted in a stable operation with high specific methane production (0.328 L/g chemical oxygen demand (COD) for non-acidulated CG and 0.345 L/g COD for acidulated CG), regarding organic loading rate of up to 4 g COD/(L x d). Due to the considerable content of dissolved inorganic salts in CG it is recommended to dilute this substrate with water to prevent the accumulation of salts and inhibition of the biomass activity. WW was proved to be a problematic substrate for anaerobic cofermentation with CG because its addition to the reactor caused a decrease in the pH value and biogas production.

Long-term monodigestion of crude glycerol in a UASB reactor.

The aim of this study was to discuss the experience from long-term operation of a laboratory UASB reactor inoculated with suspended or granulated biomass for the treatment of different kinds of crude glycerol in undiluted or diluted state. The UASB reactor was operated under mesophilic conditions. It was demonstrated that the anaerobic treatment of crude glycerol as the only substrate in the UASB reactor is feasible, although the specific inhibition effects and requirements resulting from the nature and composition of the g-phase have to be considered. Deficient concentrations of nutrients had to be compensated by their supplementation into the digester. Long-term microbiological treatment of undiluted crude glycerol led to the process inhibition due to the accumulation of dissolved inorganic salts. When dosing diluted g-phase previously treated by acidulation, very good removal efficiency of COD, stable biogas production and high share of methane in the biogas were observed at the organic loading rates of up to 12kg/(m(3)d).

Utilization of biodiesel by-products for biogas production.

This contribution reviews the possibility of using the by-products from biodiesel production as substrates for anaerobic digestion and production of biogas. The process of biodiesel production is predominantly carried out by catalyzed transesterification. Besides desired methylesters, this reaction provides also few other products, including crude glycerol, oil-pressed cakes, and washing water. Crude glycerol or g-phase is heavier separate liquid phase, composed mainly by glycerol. A couple of studies have demonstrated the possibility of biogas production, using g-phase as a single substrate, and it has also shown a great potential as a cosubstrate by anaerobic treatment of different types of organic waste or energy crops. Oil cakes or oil meals are solid residues obtained after oil extraction from the seeds. Another possible by-product is the washing water from raw biodiesel purification, which is an oily and soapy liquid. All of these materials have been suggested as feasible substrates for anaerobic degradation, although some issues and inhibitory factors have to be considered.

Nitrogen removal in an anaerobic baffled filter reactor with aerobic post-treatment.

A new sewage treatment system was studied, which consisted of an anaerobic baffled filter reactor and the following aerobic post-treatment. One of the two studied systems (AN-I) was inoculated with psychrophilic digested sludge, the second one (AN-II) was operated without inoculation. The HRT in anaerobic and aerobic parts of the reactors were about 15 and 4 h, respectively. The temperature in both reactors varied during the year from 4.5 to 23 degrees C. All monitored parameters were removed with relatively high efficiencies (COD = 78.6-83.0%, BOD5 = 92.5-94.0% and SS = 80.9-92.7%). An intensive nitrification process was observed during the whole year in both reactors (under average temperature of 5.9 degrees C in January 2000, also). The average removal of the NH4-N varied during the year from 46.4% to 87.3%. In both systems a partial denitrification process was observed, too.