Whole proteome analyses on Ruminiclostridium cellulolyticum show a modulation of the cellulolysis machinery in response to cellulosic materials with subtle differences in chemical and structural properties

Lignocellulosic materials from municipal solid waste emerge as attractive resources for anaerobic digestion biorefinery. To increase the knowledge required for establishing efficient bioprocesses, dynamics of batch fermentation by the cellulolytic bacterium Ruminiclostridium cellulolyticum were compared using three cellulosic materials, paper handkerchief, cotton discs and Whatman filter paper. Fermentation of paper handkerchief occurred the fastest and resulted in a specific metabolic profile: it resulted in the lowest acetate-to-lactate and acetate-to-ethanol ratios. By shotgun proteomic analyses of paper handkerchief and Whatman paper incubations, 151 proteins with significantly different levels were detected, including 20 of the 65 cellulosomal components, 8 non-cellulosomal CAZymes and 44 distinct extracytoplasmic proteins. Consistent with the specific metabolic profile observed, many enzymes from the central carbon catabolic pathways had higher levels in paper handkerchief incubations. Among the quantified CAZymes and cellulosomal components, 10 endoglucanases mainly from the GH9 families and 7 other cellulosomal subunits had lower levels in paper handkerchief incubations. An in-depth characterization of the materials used showed that the lower levels of endoglucanases in paper handkerchief incubations could hypothetically result from its lower crystallinity index (50%) and degree of polymerization (970). By contrast, the higher hemicellulose rate in paper handkerchief (13.87%) did not result in the enhanced expression of enzyme with xylanase as primary activity, including enzymes from the xyl-doc cluster. It suggests the absence, in this material, of molecular structures that specifically lead to xylanase induction. The integrated approach developed in this work shows that subtle differences among cellulosic materials regarding chemical and structural characteristics have significant effects on expressed bacterial functions, in particular the cellulolysis machinery, resulting in different metabolic patterns and degradation dynamics.This work was supported by a grant [R2DS 2010-08] from Conseil Regional d'Ile-de-France through DIM R2DS programs (http://www.r2ds-ile-de-france.com/). Irstea (www.irstea.fr/) contributed to the funding of a PhD grant for the first author. The funders provided support in the form of salaries for author [NB], funding for consumables and laboratory equipment, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Omics Services provided support in the form of salaries for authors [VS, MD], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors [NB, VS, MD] are articulated in the 'author contributions' section.info:eu-repo/semantics/publishedVersio

Anti-cyanobacterial activity of Moringa oleifera seeds

Filtrates from crushed Moringa oleifera seeds were tested for their effects on growth and Photosystem II efficiency of the common bloom-forming cyanobacterium Microcystis aeruginosa. M. aeruginosa populations exhibited good growth in controls and treatments with 4- and 8-mg crushed Moringa seeds per liter, having similar growth rates of 0.50 (±0.01) per day. In exposures of 20- to 160-mg crushed Moringa seeds L−1, growth rates were negative and on average −0.23 (±0.05) .day−1. Presumably, in the higher doses of 20- to 160-mg crushed seeds per liter, the cyanobacteria died, which was supported by a rapid drop in the Photosystem II efficiency (ΦPSII), while the ΦPSII was high and unaffected in 0, 4, and 8 mg L−1. High-density populations of M. aeruginosa (chlorophyll-a concentrations of ∼270 µg L−1) were reduced to very low levels within 2 weeks of exposure to ≥80-mg crushed seeds per liter. At the highest dosage of 160 mg L−1, the ΦPSII dropped to zero rapidly and remained nil during the course of the experiment (14 days). Hence, under laboratory conditions, a complete wipeout of the bloom could be achieved. This is the first study that yielded evidence for cyanobactericidal activity of filtrate from crushed Moringa seeds, suggesting that Moringa seed extracts might have a potential as an effect-oriented measure lessening cyanobacterial nuisance

Technical feasibility of the treatment of domestic wastewater by a CEPS-UASB system

Raw domestic wastewater was treated continuously under laboratory conditions for 170 days by a chemically enhanced primary sedimentation (CEPS) followed by an upflow anaerobic sludge blanket (UASB) reactor. The CEPS was carried our with 70 mg FeCl(3)l(-1) from day 1 to 82 and with 24 mi l(-1) of the water extract of Moringa oleifera seeds from day 83 to 170. Compared to the natural primary sedimentation (NPS), the CEPS increased the ratio of soluble chemical oxygen demand to volatile suspended solids (CODs/VSS) of the supernatant by a factor 3 and 10 respectively. Although the FeCl3 increased the CODs/VSS ratio, it caused a decrease of the soluble content of the wastewater by a factor 1.4. This resulted in a low influent concentration supplied to the UASB reactor and consequently a low biogas production. However, the reactor achieved 54 % removal of total COD (CODt) at a hydraulic retention time (HRT) of 2 hours and a volumetric loading rate (Bv) of 1.4 g COD l(-1) d(-1). The Moringa oleifera seeds, besides the increase of CODs/VSS ratio, also allowed to increase the CODs content of the wastewater by a factor 2.2. As a consequence, the reactor produced a higher amount of biogas. The reactor achieved 71 % removal of CODt at a HRT of 2 hours and a By of 1.4 g COD l(-1) d(-1). The UASB reactor operated without the need to discharge regularly the biological excess of sludge produced. The implementation of the CEPS can decrease the volume needed by a conventional one step UASB reactor by a factor 0.4

Anaerobic digestion technologies for closing the domestic water, carbon and nutrient cycles

Sustainable wastewater treatment requires that household wastewater is collected and treated separately from industrial wastewater and rainwater run-offs. This separate treatment is, however, still inadequate, as more than 70% of the nutrients and much of the chemical oxygen demand (COD) and potential pathogens of a domestic sewage system are confined to the few litres of black water (faeces, urine and toilet water). Whilst grey water can easily be filter treated and re-used for secondary household purposes, black water requires more intensive treatment due to its high COD and microbial (pathogens) content. Recently developed vacuum/dry toilets produce a nutrient rich semi-solid waste stream, which. with proper treatment, offers the possibility of nutrient, carbon, water and energy recovery. This study investigates the terrestrial applicability of Life Support System (LSS) concepts as a framework for future domestic waste management. The possibilities of treating black water together with other types of human-generated solid waste (biowastes/mixed wastes) in an anaerobic reactor system at thermophilic conditions, as well as some post treatment alternatives for product recovery and re-use, are considered. Energy can partially be recovered in the form of biogas produced during anaerobic digestion. The system is investigated in the form of theoretical mass balances, together with an assessment of the current feasibility of this technology and other post-treatment alternatives

Physical and biological performance of self-inoculated UASB reactor treating raw domestic sewage

The dynamics of a self-inoculated upflow anaerobic sludge blanket (UASB) reactor treating raw sewage has been studied. The results suggest two types of start-up periods. During the first 6 weeks of operation, the reactor achieved a removal efficiency of up to 65% of total chemical oxygen demand (COD) and 73% of suspended solids. During this primary start-up period, the removal of organic matter was mainly due to interception in the reactor. The second start-up period expressed by biogas release was reached after 14 weeks. An intermediary period between these two start-up periods was characterized by a slight drop of pH and increase of volatile fatty acid in the effluent. The long time to reach the second start-up period seemed to be responsible for the large discrepancy between removed COD and recovered biogas (107 mL/g COD removed). it is thus suggested that process optimization should focus on shortening the time needed to reach the second start-up period. A model that represents a possible description of the process dynamics of self-inoculated UASB reactors is proposed

Enhancing the start-up of a UASB reactor treating domestic wastewater by adding a water extract of Moringa oleifera seeds

Water extract of Moringa oleifera seeds (WEMOS) was used to enhance the start-up of a self-inoculated upflow anaerobic sludge blanket (UASB) reactor treating raw domestic wastewater. Two reactors labelled control (RC) and WEMOS addition (RM) were started without special inoculum. Both reactors were fed continuously for 22 weeks with domestic wastewater containing an average total chemical oxygen demand (COD) of 320 mg O-2/l and suspended solid (SS) of 165 mg/l. The reactors operated during the entire experimental period at 29 degreesC and at a hydraulic retention time (HRT) of 4 h. The RM reactor received 2 mi WEMOS per litre of influent. WEMOS solution was prepared on the basis of 2.5% (w/v) ground M. oleifera seeds in water. The results of 22 weeks' operation showed an improvement in the performance of the RM compared to that of the RC. The dosage of WEMOS in the feed (1) shortened the biological start-up period by 20%, (2) increased acidogenic and methanogenic activity by a factor 2.4 and 2.2 respectively, (3) increased the specific biogas production by a factor of 1.6, (4) favoured fast growth of the sludge bed, and (5) allowed the aggregation of coccoid bacteria and growth of microbial nuclei, which are precursors of anaerobic granulation