Nutritional composition of larvae of mealworm (Tenebrio molitor L) and crickets (Gryllus assimilis) with potential usage in feed / [Composição nutricional de larvas de Tenebrio molitor e de grilos (Gryllus assimilis) com potencial de uso na alimentação animal]

Atualmente, tem-se discutido a utilização de insetos na alimentação animal devido ao seu potencial para substituir as fontes tradicionais de proteína utilizadas. O objetivo deste trabalho foi determinar a composição nutricional de larvas de Tenebrio molitor e de grilos do gênero Gryllus assimilis. Os teores de energia bruta (kcal/kg), proteína bruta (g/kg), extrato etéreo (g/kg), cinza (g/kg), FDN (g/kg) e FDA (g/kg) encontrados nas larvas de Tenebrio molitor foram de 7.188,6, 490,2, 335,4, 36,8, 71,8, e 64,0 respectivamente; nos grilos (Gryllus assimilis), os valores foram de 5.942,6, 541,3, 75,2, 49,1, 277,8, e 193,0 respectivamente. Os macros e microminerais quantificados foram fósforo, potássio, sódio, cálcio, magnésio, ferro, manganês, zinco e cobre. Nas larvas de Tenebrio molitor, os valores encontrados foram de 8,56 g/kg, 8,39 g/kg, 1,39 g/kg, 0,44 g/kg, 2,3 g/kg, 48,4 mg/kg, 15 mg/kg, 189 mg/kg e 18 mg/kg respectivamente. Para os grilos (Gryllus assimilis), os teores encontrados foram respectivamente de 8,30 g/kg, 11,6 g/kg, 1,10 g/kg, 3,88 g/kg, 0,82 g/kg, 96,8 mg/kg, 23,7 mg/kg, 18,3 mg/kg e 21,7 mg/kg. Larvas de Tenebrio molitor e grilos do gênero Gryllus assimilis podem ser alternativas para reduzir o uso de fontes de proteína vegetal na alimentação animal.(AU)

Characterisation and control of the biosolids storage environment: Implications for E. coli dynamics.

E. coli survival in biosolids storage may present a risk of non-compliance with guidelines designed to ensure a quality product safe for agricultural use. The storage environment may affect E. coli survival but presently, storage characteristics are not well profiled. Typically biosolids storage environments are not actively controlled or monitored to support increased product quality or improved microbial compliance. This two-phased study aimed to identify the environmental factors that control bacterial concentrations through a long term, controlled monitoring study (phase 1) and a field-scale demonstration trial modifying precursors to bacterial growth (phase 2). Digested and dewatered biosolids were stored in operational-scale stockpiles to elucidate factors controlling E. coli dynamics. E. coli concentrations, stockpile dry solids, temperature, redox and ambient weather data were monitored. Results from ANCOVA analysis showed statistically significant (p < 0.05) E. coli reductions across storage periods with greater die-off in summer months. Stockpile temperature had a statistically significant effect on E. coli survival. A 4.5 Log reduction was measured in summer (maximum temperature 31 °C). In the phase 2 modification trials, covered stockpiles were able to maintain a temperature >25 °C for a 28 day period and achieved a 3.7 Log E. coli reduction. In winter months E. coli suppression was limited with concentrations >6 Log10 CFU g-1 DS maintained. The ANCOVA analysis has identified the significant role that physical environmental factors, such as stockpile temperature, has on E. coli dynamics and the opportunities for control.

Costs and benefits of sublethal Drosophila C virus infection.

Viruses are major evolutionary drivers of insect immune systems. Much of our knowledge of insect immune responses derives from experimental infections using the fruit fly Drosophila melanogaster. Most experiments, however, employ lethal pathogen doses through septic injury, frequently overwhelming host physiology. While this approach has revealed several immune mechanisms, it is less informative about the fitness costs hosts may experience during infection in the wild. Using both systemic and oral infection routes, we find that even apparently benign, sublethal infections with the horizontally transmitted Drosophila C virus (DCV) can cause significant physiological and behavioural morbidity that is relevant for host fitness. We describe DCV-induced effects on fly reproductive output, digestive health and locomotor activity, and we find that viral morbidity varies according to the concentration of pathogen inoculum, host genetic background and sex. Notably, sublethal DCV infection resulted in a significant increase in fly reproduction, but this effect depended on host genotype. We discuss the relevance of sublethal morbidity for Drosophila ecology and evolution, and more broadly, we remark on the implications of deleterious and beneficial infections for the evolution of insect immunity.

Apixaban versus enoxaparin in the prevention of venous thromboembolism following total knee arthroplasty: a single-centre, single-surgeon, retrospective analysis.

BACKGROUND: There is a high risk of developing venous thromboembolism (VTE) following total knee arthroplasty (TKA). Conventional thromboprophylactic agents have limitations, such as route of administration, the need for monitoring, narrow therapeutic windows and interactions. Apixaban is a new oral anticoagulant with the potential to overcome these limitations. AIMS: To report the efficacy and safety of apixaban and low-molecular-weight heparin, enoxaparin, in VTE prophylaxis following TKA. METHODS: This single-centre, single-surgeon, retrospective analysis included 506 consecutive patients who underwent TKA between 2009 and 2015 and received enoxaparin or apixaban as thromboprophylaxis. Baseline characteristics of patients, in-hospital rates of VTE, total DVT, proximal or distal DVT, pulmonary embolism, bleeding outcomes and mortality were compared between the two groups. RESULTS: In-hospital VTE occurred in 22 (8.9%) patients in the enoxaparin group and 11 (4.5%) patients in the apixaban group (P = 0.049). Nine (3.6%) patients in the enoxaparin group and one (0.4%) in the apixaban group experienced a postoperative drop in haemoglobin ≥20 g/L that either necessitated transfusion of ≥2 units blood, caused haemodynamic instability or both (P = 0.020). Thirty-five patients experienced other bleeding events, with 25 (9.9%) in the enoxaparin group and 10 (4.0%) in the apixaban group (P = 0.009). There were no statistically significant differences in rates of total DVT, proximal or distal DVT, pulmonary embolism or mortality between the groups. CONCLUSIONS: Compared with enoxaparin, thromboprophylaxis with apixaban resulted in a lower VTE incidence and fewer haemorrhagic complications.

Biological carbon dioxide utilisation in food waste anaerobic digesters.

Carbon dioxide (CO2) enrichment of anaerobic digesters (AD) was previously identified as a potential on-site carbon revalorisation strategy. This study addresses the lack of studies investigating this concept in up-scaled units and the need to understand the mechanisms of exogenous CO2 utilisation. Two pilot-scale ADs treating food waste were monitored for 225 days, with the test unit being periodically injected with CO2 using a bubble column. The test AD maintained a CH4 production rate of 0.56 ± 0.13 m(3) CH4·(kg VS(fed) d)(-1) and a CH4 concentration in biogas of 68% even when dissolved CO2 levels were increased by a 3 fold over the control unit. An additional uptake of 0.55 kg of exogenous CO2 was achieved in the test AD during the trial period. A 2.5 fold increase in hydrogen (H2) concentration was observed and attributed to CO2 dissolution and to an alteration of the acidogenesis and acetogenesis pathways. A hypothesis for conversion of exogenous CO2 has been proposed, which requires validation by microbial community analysis.

Development of on-line FTIR spectroscopy for siloxane detection in biogas to enhance carbon contactor management.

Activated carbon filters are used to limit engine damage by siloxanes when biogas is utilised to provide electricity. However, carbon filter siloxane removal performance is poorly understood as until recently, it had not been possible to measure siloxanes on-line. In this study, on-line Fourier Transform Infrared (FTIR) spectroscopy was developed to measure siloxane concentration in real biogas both upstream (86.1-157.5mg m(-3)) and downstream (2.2-4.3mg m(-3)) of activated carbon filters. The FTIR provided reasonable precision upstream of the carbon vessel with a root mean square error of 10% using partial least squares analysis. However, positive interference from volatile organic carbons was observed in downstream gas measurements limiting precision at the outlet to an RMSE of 1.5mg m(-3) (47.8%). Importantly, a limit of detection of 3.2mg m(-3) was identified which is below the recommended siloxane limit and evidences the applicability of on-line FTIR for this application.

Thromboprophylaxis in patients undergoing total hip and knee arthroplasty: a review of current practices in an Australian teaching hospital.

BACKGROUND: Venous thromboembolism (VTE) remains a cause of significant morbidity and mortality following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Prophylaxis significantly reduces the rate of VTE following these procedures. Previous studies report suboptimal uptake of guideline recommended thromboprophylaxis. AIMS: To describe VTE prophylaxis prescribing practices in a major hospital for joint replacement surgery. To determine the proportion of patients receiving guideline recommended thromboprophylaxis. To define the incidence of in-hospital VTE following THA and TKA. METHODS: A retrospective chart review of 402 consecutive patients undergoing THA or TKA from June to October 2013. Patient characteristics, operative and anaesthetic factors, details of thromboprophylaxis and the incidence of in-hospital VTE are reported. Comparison is made with recent guidelines. RESULTS: Four hundred and two patients underwent THA (n = 202) or TKA (n = 200). Ninety-nine per cent of patients received mechanical prophylaxis. One hundred percent of patients received chemoprophylaxis in hospital. Enoxaparin was most commonly prescribed followed by aspirin. Patients undergoing TKA were more likely to receive an anticoagulant (89.9% vs 47.8% for THA, P < 0.05). 74.5% received chemoprophylaxis on discharge (mean duration 22.1 days). The incidence of in-hospital VTE was 4.7%. CONCLUSIONS: The proportion of study patients receiving thromboprophylaxis compares favourably with prior research. The overall incidence of VTE is higher than that demonstrated in major orthopaedic trials. Inadequate duration of chemoprophylaxis remains a potential area of improvement. Extended prophylaxis should be prescribed as per current guidelines. Comparison between efficacy and safety of various agents is the subject of future research.

Removal of phosphorus from trickling filter effluent by electrocoagulation.

As regulatory requirements for contaminants in wastewater discharged to the environment get stricter, alternative or additional treatment processes to those already being used are necessary. One contaminant of particular concern associated with discharging treated municipal wastewater to a receiving water body is phosphorus (P). A continuous scale electrocoagulation (EC) system was investigated as an alternative to conventional chemical addition for P removal from municipal wastewater. The EC process was optimized for iron dose delivery by changing the electrical current, electrode spacing and the reactor contact time, and a comparison was made with conventional ferric dosing through jar testing. Results showed that EC could achieve P removal to meet a P consent of 1 mg L⁻¹ at a dose of 154 mg L⁻¹ Fe. The process was shown to provide a supplementary benefit for chemical and biological oxygen demand removal of 86% and 82%, respectively, but gave no significant removal of other sanitary pollutants. When compared directly with conventional iron dosing, EC required approximately twice the iron dose. When electrical costs were also factored into the comparison, EC was shown to be approximately double the cost of conventional dosing and at present is not a feasible alternative to conventional coagulation using ferric chloride.

Carbon capture and biogas enhancement by carbon dioxide enrichment of anaerobic digesters treating sewage sludge or food waste.

The increasing concentration of carbon dioxide (CO2) in the atmosphere and the stringent greenhouse gases (GHG) reduction targets, require the development of CO2 sequestration technologies applicable for the waste and wastewater sector. This study addressed the reduction of CO2 emissions and enhancement of biogas production associated with CO2 enrichment of anaerobic digesters (ADs). The benefits of CO2 enrichment were examined by injecting CO2 at 0, 0.3, 0.6 and 0.9 M fractions into batch ADs treating food waste or sewage sludge. Daily specific methane (CH4) production increased 11-16% for food waste and 96-138% for sewage sludge over the first 24h. Potential CO2 reductions of 8-34% for sewage sludge and 3-11% for food waste were estimated. The capacity of ADs to utilise additional CO2 was demonstrated, which could provide a potential solution for onsite sequestration of CO2 streams while enhancing renewable energy production.

The evolution of resistance against good and bad infections.

Opportunities for genetic exchange are abundant between bacteria and foreign genetic elements (FGEs) such as conjugative plasmids, transposable elements and bacteriophages. The genetic novelty that may arise from these forms of genetic exchange is potentially beneficial to bacterial hosts, but there are also potential costs, which may be considerable in the case of phage infection. Some bacterial resistance mechanisms target both beneficial and deleterious forms of genetic exchange. Using a general epidemiological model, we explored under which conditions such resistance mechanisms may evolve. We considered a population of hosts that may be infected by FGEs that either confer a benefit or are deleterious to host fitness, and we analysed the epidemiological and evolutionary outcomes of resistance evolving under different cost/benefit scenarios. We show that the degree of co-infection between these two types of infection is particularly important in determining the evolutionarily stable level of host resistance. We explore these results using the example of CRISPR-Cas, a form of bacterial immunity that targets a variety of FGEs, and we show the potential role of bacteriophage infection in selecting for resistance mechanisms that in turn limit the acquisition of plasmid-borne antibiotic resistance. Finally, beyond microbes, we discuss how endosymbiotic associations may have shaped the evolution of host immune responses to pathogens.

[Can solar/geomagnetic activity restrict the occurrence of some shellfish poisoning outbreaks? The example of PSP caused by Gymnodinium catenatum at the Atlantic Portuguese coast].

Cyclic outbreaks of accumulation of paralytic shellfish poisoning (PSP) toxins in mussels attributed to Gymnodinium catenatum blooms displayed several of the highest inter-annual maxima coincidental with minima of the 11-year solar sunspot number (SSN) cycle. The monthly distribution of PSP was associated with low levels of the solar radio flux, a more quantitative approach than SSN for fluctuations in solar activity. A comparison between monthly distribution of PSP and other common biotoxins (okadaic acid (OA), dinophysistoxin-2 (DTX2) and amnesic shellfish poisoning (ASP) toxins) demonstrated that only PSP was significantly associated with low levels of radio flux (p < 0.01). PSP occurrence suggests a prior decline in solar activity could be required to act as a trigger, in a similar manner to a photoperiodic signal. The seasonal frequency increased towards autumn during the study period, which might be related to the progressive atmospheric cut-off of deleterious radiation associated with the seasonal change in solar declination, and might play an additional role in seasonal signal-triggering. PSP distribution was also associated with low levels of the geomagnetic index Aa. A comparison between monthly distribution of PSP and other common biotoxins, also demonstrated that only PSP was significantly associated with low levels of the Aa index (p < 0.01). In some years of SSN minima no significant PSP-outbreaks in mussels were detected. This was attributed to a steady rise in geomagnetic activity that could disrupt the triggering signal. Global distribution patterns show that hotspots for G. catenatum blooms are regions with deficient crustal magnetic anomalies. In addition to the variable magnetic field mostly of solar origin, static fields related to magnetized rocks in the crust and upper mantle might play a role in restricting worldwide geographic distribution.

Fecundity compensation and tolerance to a sterilizing pathogen in Daphnia.

Hosts are armed with several lines of defence in the battle against parasites: they may prevent the establishment of infection, reduce parasite growth once infected or persevere through mechanisms that reduce the damage caused by infection, called tolerance. Studies on tolerance in animals have focused on mortality, and sterility tolerance has not been investigated experimentally. Here, we tested for genetic variation in the multiple steps of defence when the invertebrate Daphnia magna is infected with the sterilizing bacterial pathogen Pasteuria ramosa: anti-infection resistance, anti-growth resistance and the ability to tolerate sterilization once infected. When exposed to nine doses of a genetically diverse pathogen inoculum, six host genotypes varied in their average susceptibility to infection and in their parasite loads once infected. How host fecundity changed with increasing parasite loads did not vary between genotypes, indicating that there was no genetic variation for this measure of fecundity tolerance. However, genotypes differed in their level of fecundity compensation under infection, and we discuss how, by increasing host fitness without targeting parasite densities, fecundity compensation is consistent with the functional definition of tolerance. Such infection-induced life-history shifts are not traditionally considered to be part of the immune response, but may crucially reduce harm (in terms of fitness loss) caused by disease, and are a distinct source of selection on pathogens.

Presence of benzoate type toxins in Gymnodinium catenatum Graham isolated from the Mexican Pacific.

Benzoate type toxins have been described as an important component of Gymnodinium catenatum cells. In this paper we study these toxins in a G. catenatum strain isolated from the Mexican coast. A partition of the toxins was done by solid-phase extraction on a COOH cartridge and detected by HPLC coupled to fluorescence after pre-column periodate oxidation. Two groups of the hydrophobic analogues of saxitoxin were identified: those containing a sulphate group in the benzoate moiety instead of a hydroxyl group like GC1/2 or GC3 and the hydroxy-benzoate analogues, with a sulphate group at the eleventh position of the STX core present or absent (GCs-GTX and GCs-STX analogues, respectively). These toxins are more abundant, in a relative basis, when comparing with a G. catenatum toxin content isolated from Portugal. This is the first report of the presence of these toxins in a Mexican strain.

Assessment of a new lateral flow immunochromatographic (LFIC) assay for the okadaic acid group of toxins using naturally contaminated bivalve shellfish from the Portuguese coast.

A new rapid assay for the okadaic acid group of toxins, based on lateral flow immunochromatographic (LFIC) test strips developed by Jellett Rapid Testing Ltd., was assessed on naturally contaminated bivalves from the Portuguese coast. One prototype was evaluated using samples harvested during 2005, extracted with 80% methanol, followed by dilution with the running buffer of a methanolic extract after alkaline hydrolysis for esters. The second prototype was assessed using samples harvested during 2006, extracted with 100% methanol and, after alkaline hydrolysis, the methanol was evaporated by a nitrogen stream followed by re-suspension with the running buffer. The first prototype failed to detect 20% of samples that were positive by LC-MS in the range 160-480 microg kg(-1), and were classified as negative or trace level by LFIC. The presence of methanol in the extracts made correct detection of toxins more difficult. The second prototype classified as positive all samples above 160 microg kg(-1), as confirmed by LC-MS. However, in the second prototype, matrix effects were a major drawback and led to 45% false positives, particularly for mussels, due to compounds in shellfish extracts interfering with the antibodies and reducing the test line intensity. Extraction with a higher percentage of methanol was thought responsible for these matrix effects. Regarding sample migration, both prototypes needed one hour before reading. In an attempt to speed-up sample preparation, a direct digestion of bivalve tissues with sodium hydroxide was evaluated. Low recoveries for esters were found by LC-MS with this hydrolysis technique compared to conventional hydrolysis of methanolic extracts. While prototype A was not sensitive enough, prototype B had too many false positives to be of use to the shellfish industry or in a monitoring program.

Extraction recoveries and stability of diarrhetic shellfish poisoning (DSP) toxins in naturally contaminated samples.

During the last few years the occurrence of a high percentage of esters of diarrhetic shellfish poisoning (DSP) toxins has been observed in shellfish from the Portuguese coast. Most of the commercial bivalves contain DSP toxins in ester forms, either acyl derivatives of okadaic acid (OA) or of dinophysistoxin-2 (DTX-2). The stability of these toxins in shellfish tissues and in raw methanol extracts was investigated in two different naturally contaminated species, mussel and carpet shell, over a 4-week period. The results for both species revealed that DSP toxins were more stable in tissue than in raw methanol extracts. Losses of DSP toxins were seen in the first 2 weeks and were more than 30%, but after that a period of stabilization was observed. The decrease was due probably from losses of esters of OA and DTX-2, the free toxins were stable over the period studied. The extraction most commonly used for chemical and biochemical assays relied on methanolic extraction with aqueous 80% methanol. In this work we have tested the extraction solvent on the extractability of DSP toxins from several naturally contaminated species. A single dispersive extraction with methanol, with solvent ratios of 70%, 80%, 90% and 100%, were tested. After alkaline hydrolysis of esterified toxins and clean-up with hexane and dichloromethane, the samples were analysed by liquid chromatography-mass spectrometry (LC-MS). The recovery of DSP toxins increased with increasing percentages of methanol up to 90%. A decrease in recovery with 100% methanol was observed probably due to problems during the liquid-liquid partitioning.

Measuring parasite fitness under genetic and thermal variation.

Accurate measures of parasite fitness are essential to study host-parasite evolution. Parasite fitness depends on several traits involved in establishing infection, growth and transmission. Individually, these traits provide a reasonable approximation of fitness, but they may also be under the shared control of both host and parasite genetics (G(H) x G(P) interactions), or be differentially sensitive to environmental variation. Using the natural host-parasite system Daphnia magna-Pasteuria ramosa, we performed experimental infections that incorporated host and parasite genetic variation at three different temperatures, and compared the measures of parasite fitness based only on growth rate, or incorporating the ability to infect. We found that infectivity was most important for parasite fitness and depended mainly on the combination of host and parasite genotypes. Variation in post-infection parasite growth and killing time depended on the parasite genotype and its interaction with temperature. These results highlight the merits of studies that can incorporate natural infection routes and emphasize that accurate measures of parasite fitness require knowledge of the genetic control and environmental sensitivity of more than one trait. In addition, no G(H) x G(P) x E interactions were present, suggesting that the potential for genetic specificities to drive frequency-dependent coevolution in this system is robust to thermal variation.

Temperature-dependent costs of parasitism and maintenance of polymorphism under genotype-by-environment interactions.

The maintenance of genetic variation for infection-related traits is often attributed to coevolution between hosts and parasites, but it can also be maintained by environmental variation if the relative fitness of different genotypes changes with environmental variation. To gain insight into how infection-related traits are sensitive to environmental variation, we exposed a single host genotype of the freshwater crustacean Daphnia magna to four parasite isolates (which we assume to represent different genotypes) of its naturally co-occurring parasite Pasteuria ramosa at 15, 20 and 25 degrees C. We found that the cost to the host of becoming infected varied with temperature, but the magnitude of this cost did not depend on the parasite isolate. Temperature influenced parasite fitness traits; we found parasite genotype-by-environment (G x E) interactions for parasite transmission stage production, suggesting the potential for temperature variation to maintain genetic variation in this trait. Finally, we tested for temperature-dependent relationships between host and parasite fitness traits that form a key component of models of virulence evolution, and we found them to be stable across temperatures.

Topical anesthesia versus sub-Tenon block for cataract surgery: surgical conditions and patient satisfaction.

PURPOSE: To compare the surgical conditions and complications and patient and surgeon satisfaction in cataract surgery by phacoemulsification under topical anesthesia (TA) versus sub-Tenon block (STB). METHODS: Prospective randomized comparative blind study, without placebo control. Patient satisfaction evaluated by the Iowa Satisfaction with Anesthesia Scale (ISAS). RESULTS: The authors prospectively enrolled 59 patients (61% female) in the study, who were randomized into groups: 26 in the TA group and 33 in the STB. There was no statistically significant difference between the groups in terms of age, sex, waiting time for surgery, ASA (American Society of Anesthesiologists) state, eye laterality, cataract density, pupillary dilation, or surgery duration, but patient collaboration was better in the STB group. We found a mean 2.2 mmHg post-anesthetic rise in intraocular pressure in the STB group, with normalization at 24 hours, and no rise in the TA group. Subconjunctival hemorrhage and chemosis were more prevalent in the STB group, and the improvement of visual acuity was similar in both groups. Subjective satisfaction with the anesthetic technique, both for the surgeon and for the patient, was more elevated in the STB group. The final ISAS scores were 1.87 in the TA group and 2.71 in the STB (p<0.005). CONCLUSIONS: The data indicate that more significant anesthesia and analgesia was achieved with the STB, leading to more favorable surgical conditions and enhanced patient and surgeon satisfaction.

Mechanical sludge disintegration: providing an alternative carbon source for nutrient removal.

The primary driver for efficient biological nutrient removal (BNR) in activated sludge treatment is the sufficient supply of soluble carbon. Several methods have been proposed to increase available carbon sources and enhance BNR. This study examines the effect of ultrasonic equipment and mechanical disintegration technologies on surplus activated sludge (SAS), to release additional soluble chemical oxygen demand (SCOD) and volatile fattty acids (VFA), as a carbon food source for BNR. A laboratory sonicator with a maximum power of 550W, a 3KW SONIX radial horn and a deflaker declared to be used in the paper industry were investigated. All caused significant release of SCOD, up to 48 fold. The maximum concentration of VFA reached (from 0-1 mg 1(-1)), was 530 mg 1(-1). To assess the likely impact to BNR, batch (21) anaerobic lab tests examining the use of disintegrated sludge on phosphorus and nitrogen removal were completed. Phosphorus removal was estimated by observing the phosphate release under anaerobic conditions and up to 460% more release was observed relative to controls. In addition, denitrification rates were improved by over 106%. Ultrasonic and mechanical disintegration technologies have been shown to release soluble carbon for BNR, with subsequent laboratory nitrogen and phosphorus removal efficiencies observed to be comparable to acetate.

Mechanical sludge disintegration for the production of carbon source for biological nutrient removal.

The primary driver for a successful biological nutrient removal is the availability of suitable carbon source, mainly in the form of volatile fatty acids (VFA). Several methods have been examined to increase the amount of VFAs in wastewater. This study investigates the mechanism of mechanical disintegration of thickened surplus activated sludge by a deflaker technology for the production of organic matter. This equipment was able to increase the soluble carbon in terms of VFA and soluble chemical oxygen demand (SCOD) with the maximum concentration to be around 850 and 6530 mgl(-1), for VFA and SCOD, respectively. The particle size was reduced from 65.5 to 9.3 microm after 15 min of disintegration with the simultaneous release of proteins (1550 mgl(-1)) and carbohydrates (307 mgl(-1)) indicating floc disruption and breakage. High performance size exclusion chromatography investigated the disintegrated sludge and confirmed that the deflaker was able to destroy the flocs releasing polymeric substances that are typically found outside of cells. When long disintegration times were applied (>or=10 min or >or=9000 kJkg(-1)TS of specific energy) smaller molecular size materials were released to the liquid phase, which are considered to be found inside the cells indicating cell lysis.