Acclimation Phase Research Articles

Disturbances in the Biosynthesis or Signalling of Brassinosteroids That Are Caused by Mutations in the HvDWARF, HvCPD and HvBRI1 Genes Increase the Tolerance of Barley to the Deacclimation Process

Tolerance to deacclimation is an important physiological feature in plants in the face of global warming, which is resulting in incidents of increases in winter temperatures. The aim of the work was to explore how disturbances in the signalling and synthesis of brassinosteroids (BR) influence the deacclimation tolerance of barley. One group of mutants and their reference cultivars (Bowman and Delisa) was cold-acclimated, deacclimated and then tested for frost tolerance at − 12 °C. After cold acclimation, the second group of plants was additionally exposed to frost (− 6 °C) and then, deacclimated and tested for frost tolerance at − 12 °C. The deacclimated brassinosteroid mutants were characterised by an increased tolerance to frost, and consequently, had a higher tolerance to deacclimation than their wild-type cultivars. The mechanism of this phenomenon may be partly explained by analysing the hormonal homeostasis in the crowns. For all of the tested plants, a characteristic feature of the response to the deacclimation phase was an increase in the growth-promoting hormones and abscisic acid compared to the cold acclimation phase. The increase was greater in the BR-deficient (BW084) and BR-insensitive (BW312) mutants compared to the Bowman reference cultivar. Mutant 522DK was characterised by a lower accumulation of total cytokinins and gibberellins as well as an enhanced auxin deactivation compared to the Delisa. In the second group, when the plants were exposed to a temperature of − 6 °C before deacclimation, the hormonal homeostasis was further altered in both the mutants and reference cultivars, but all of the mutants had a higher frost tolerance than the wild types.

Anaerobic phenol biodegradation: kinetic study and microbial community shifts under high-concentration dynamic loading.

The anaerobic biodegradation of phenol has been realised in a sequencing batch reactor (SBR) under anaerobic conditions with phenol as sole carbon and energy source and with glucose as co-substrate. A step-change increase of phenol loading (from 100 up to 2000mg/L of phenol concentration in the feed solution) has been applied during the acclimation phase in order to progressively induce the development of a specialised microbial consortium. This approach, combined with the dynamic sequence of operations characterising SBRs and with the high biomass retention time, led to satisfactory phenol and COD removal efficiencies with values > 70% for the highest phenol input (2000mg/L) fed as the single carbon and energy source. Analysis of removal efficiencies and biodegradation rates suggested that the use of glucose as co-substrate did not induce a significant improvement in process performance. Kinetic tests have been performed at different initial phenol (400-1000mg/L) and glucose (1880-0mg/L) concentrations to kinetically characterise the developed biomass: estimated kinetic constants are suitable for application and no inhibitory effect due to high concentrations of phenol has been observed in all investigated conditions. The microbial community has been characterised at different operating conditions through molecular tools: results confirm the successful adaptation-operation approach of the microbial consortium showing a gradual increase in richness and diversity and the occurrence and selection of a high proportion of phenol-degrading genera at the end of the experimentation. Key Points • Anaerobic phenol removal in the range of 70-99% in a sequencing batch reactor. • Negligible effect of co-substrate onremoval efficiencies and biodegradation rates. • No biomass inhibition due to phenol concentration in the range of 400-1000mg/L. • Increasing phenol loads promoted the culture enrichment of phenol-degrading genera.

0277 Sleep Restriction does not Alter the Transcription of Adipose Tissue Insulin-Signaling Regulators

Abstract Introduction Voluntary sleep curtailment decreases insulin sensitivity. However, molecular mechanisms underlying impaired insulin signaling are not completely understood. To gain molecular insights, we examined the transcription of known cellular insulin-signaling regulators in adipose tissue obtained from subjects undergoing experimental sleep restriction. Methods Nineteen healthy subjects (males: 11; age: 19 - 36 years; BMI: 24.5 ± 3.6 kg/m2) underwent a normal (9 hours/night) and a restricted sleep (4 hours/night) sequence in a random order. Each inpatient stay included a screen visit followed by 4 days of acclimation and 9 days of experimental phase consisting of a controlled sleep opportunity. Eucaloric diet was provided to ensure weight maintenance. Abdominal fat sample was obtained at the screen and end of the experimental phase. mRNA was quantified by RT-PCR. Fasting morning blood draws were obtained at the end of acclimation and experimental phases. Mixed models were used for analysis. Results mRNA expression did not differ in normal and restricted sleep condition for SOCS3 [changes in normal Vs. restricted sleep, 0.02 (0.11, -0.01) Vs. 0.01 (0.12, -0.07), p=0.33], PTEN [-0.22 (0.18, -0.39) Vs. -0.10 (0.21, -0.20), p=0.22], PTB1B [-0.003 (0.04, -0.07) Vs. -0.01 (0.06, -0.06), p=0.74] and Cav-1 [-2.45 (0.78, -8.39) Vs. -6.31 (1.68, -8.29), p=0.34]. Further, transcription of insulin-receptor also did not change [0.01 (0.07, -0.06) Vs. -0.03 (0.09, -0.07), p=0.92]. However, within group analysis show significant decreases in Cav-1 mRNA only during sleep restriction (normal: p=0.09; restricted: p=0.003). Importantly, restricting sleep duration was associated with lowering of insulin (0.6 ± 1.9 Vs. -1.6 ± 1.7 uIU/ml; p=0.003), no change in glucose (-1.5 ± 3.8 Vs. -3.7 ± 4.12 mg/dl, p=0.06) and improvement in HOMA-IR index (0.12 ± 0.44 Vs -0.42 ± 0.43, p=0.002). Conclusion Chronic sleep restriction does not alter the transcription of cell-signaling regulators in abdominal adipose tissue. Moreover, restricting sleep duration without increasing calorie intake did not seem to decrease insulin sensitivity as determined by HOMA-IR. Support NIH grants HL114676, Mayo Clinic CCaTS UL1 TR002377; AHA grant 13POST16420009 to NC

Laboratory and on‐farm evaluation of low‐cost salt mixtures for use during salinity acclimation and the nursery phase of Pacific white shrimp ( Litopenaeus vannamei )

The current study evaluates the efficacy of a low-cost salt mixture (LCSM) to replace expensive reconstituted sea salt (RSS) in the salinity acclimation and nursery phase of Pacific white shrimp under laboratory and farm conditions. LCSM was formulated to yield sodium, potassium, calcium and magnesium concentrations closely comparable to that of diluted seawater. Laboratory-based nursery trials were conducted at 2, 6 and 15 g/L salinities, incrementally replacing RSS with LCSM (25%, 50%, 75% and 100%) at four replicates per treatment. Thirty postlarvae were reared for 7 days in 24-L aquaria during the 2 and 6 g/L trials, while the nursery trial for 15 g/L salinity was conducted for 21 days with 400 postlarvae stocked in 150-L tanks. On-farm evaluation of LCSM was carried out in two tank-based systems installed on levees adjacent to shrimp production ponds. RSS was incrementally replaced with LCSM (0%, 50%, 75% and 100%) and 100 postlarvae stocked into each 800-L tank. Salinity acclimation was done from 30 g/L to 6 or 1.5 g/L within 2–3 days by pumping water from adjacent shrimp production ponds. Following salinity acclimation, the S4 system maintained flow-through at 1.5 g/L, while N10 system was maintained static at 6 g/L salinity. At the conclusion, no significant differences were observed for either survival or growth of shrimp postlarvae between RSS and LCSM treatments at all salinities examined. Results reflect the potential use of LCSM to replace RSS, which could be an excellent solution to bring down the cost of production in inland shrimp aquaculture.

Adaptation to salinity: Response of biogas production and microbial communities in anaerobic digestion of kitchen waste to salinity stress

Salinity stress during anaerobic digestion is known to cause extensive changes in biogas production and microbial community structure. Thus, our study sought to characterize the adaptation response of bacteria when challenged with increased salinity. Firstly, experiments were conducted at eight salinity levels at a constant kitchen waste/inoculum ratio (K/I= 1.0), which indicated that the effect of salinity on anaerobic digestion was strictly dosage-dependent. Then, kitchen waste anaerobic digestion was conducted for 70 days at five increasing salinity levels (1.0, 2.0, 4.0, 8.0, and 16.0g NaCl/g). Furthermore, six samples taken at the end of each salinity level acclimation phase were analyzed by high-throughput sequencing, which illustrated that Euryarchaeota, Synergistetes, Firmicutes, and Bacteroidetes were dominance at phylum level. Moreover, the proportion of Methanosaeta as major genus among Euryarchaeota was 16.46% after being acclimated 70 days of NaCl acclimation, which was higher than its proportions at the initial sample (22.08%). Methanosarcina were also enriched after acclimation. Therefore, Methanosaeta and Methanosarcina could both potentially adapt to high-salinity environments.

Growth of pre-sprouted sugarcane seedlings submitted to supplementary lighting

ABSTRACT Brazil is the largest producer and exporter of sugarcane in the world, and the sugar and ethanol sector has invested in the development of new technologies and methods of planting to meet the market demand. Thus, the aim of this study was to evaluate the performance of sugarcane at the acclimation phase and under field conditions, from pre-sprouted seedlings exposed to supplementary lighting, through light-emitting diode, in the period of acclimation in a greenhouse. The experiment was carried out in Carpina, PE, Brazil, from January to September 2017. The experimental plots were composed of pre-sprouted seedlings acclimated in greenhouse, exposed to the supplementary lighting systems, 90% Red + 10% Blue (R:B 90/10), 80% Red + 20% Blue (R:B 80/20), 70% Red + 30% Blue (R:B 70/30) and a control. The evaluation of seedling growth was performed through the measurement of biometric indicators: plant height (cm); stem length (cm); stem diameter (cm) and number of tillers. The biometric indicators showed no significant differences, but plants under lighting systems with a greater proportion of the red wavelength (R:B 80/20 and R:B 90/10) showed higher percentage of survival in the field.

Does Dehydration Affect the Adaptations of Plasma Volume, Heart Rate, Internal Body Temperature, and Sweat Rate During the Induction Phase of Heat Acclimation?

Clinical Scenario: Exercise in the heat can lead to performance decrements and increase the risk of heat illness. Heat acclimation refers to the systematic and gradual increase in exercise in a controlled, laboratory environment. Increased duration and intensity of exercise in the heat positively affects physiological responses, such as higher sweat rate, plasma volume expansion, decreased heart rate, and lower internal body temperature. Many heat acclimation studies have examined the hydration status of the subjects exercising in the heat. Some of the physiological responses that are desired to elicit heat acclimation (ie,higher heart rate and internal body temperature) are exacerbated in a dehydrated state. Thus, euhydration (optimal hydration) and dehydration trials during heat acclimation induction have been conducted to determine if there are additional benefits to dehydrated exercise trials on physiological adaptations. However, there is still much debate over hydration status and its effect on heat acclimation. Clinical Question: Does dehydration affect the adaptations of plasma volume, heart rate, internal body temperature, skin temperature, and sweat rate during the induction phase of heat acclimation? Summary of Findings: There were no observed differences in plasma volume, internal body temperature, and skin temperature following heat acclimation in this critically appraised topic. One study found an increase in sweat rate and another study indicated greater changes in heart rate following heat acclimation with dehydration. Aside from these findings, all 4 trials did not observe statistically significant differences in euhydrated and dehydrated heat acclimation trials. Clinical Bottom Line: There is minimal evidence to suggest that hydration status affects heat acclimation induction. In the studies that met the inclusion criteria, there were no differences in plasma volume concentrations, internal body temperature, and skin temperature. Strength of Recommendation: Based on the Oxford Centre for Evidence-Based Medicine Scale, Level 2 evidence exists.

Micropropagación de Prosopis pallida (Humb &Bonpl. Ex Willd.) Kunth a partir de yemas apicales

Prosopis pallida, conocido como algarrobo, es una especie emblemática de los bosques secos del norte del Perú. Es de gran importancia económica por su uso en la producción de leña y carbón, así como en la producción de algarrobina proveniente de sus frutos. Actualmente las actividades humanas han deforestado grandes poblaciones de algarrobo en el bosque seco, por lo que es muy importante una propagación masiva para planes de reforestación a gran escala en esos ecosistemas, con la finalidad de conservar la especie y también las características genéticas de individuos élite. El objetivo de la investigación fue establecer un protocolo para la propagación in vitro de algarrobo. Previo a la siembra in vitro, se evaluaron tres tratamientos pregerminativos para poder acelerar la germinación de las semillas con la finalidad de obtener mayor material de propagación. Luego se evaluó el efecto del medio de plantas leñosas con la adición de cuatro concentraciones (0; 0,5; 1,0 y 1,5 mg/L) de citoquininas (BAP y ZEA) sobre la propagación in vitro de Prosopis pallida, habiendo realizado tres ensayos debido a la poca efectividad de brotación de las yemas apicales, resultando mejor la ausencia de citoquininas en yemas apicales con sus dos cotiledones, usando tapas de algodón en los tubos de ensayo. En esta etapa se evaluó el número de nudos, altura de plántula y número de brotes. Para el enraizamiento se ensayó con tres concentraciones (0; 0,5 y 1,0 mg/L) de auxinas (NAA, IBA y IAA), y se evaluó el porcentaje de enraizamiento, longitud de la raíz y número de raíces; obteniéndose mejores resultados con 0,5 mg/L IBA. En la fase de aclimatación se evaluó el porcentaje de aclimatación en dos tipos de sustratos, obteniéndose mejores resultados con sustrato comercial de turba y vermiculita.

Microbial Community Rearrangements in Power-to-Biomethane Reactors Employing Mesophilic Biogas Digestate

The biological conversion of hydrogen (H2) and carbon dioxide (CO2) to methane (CH4), is accomplished by the hydrogenotrophic methanogens (HM). HMs are difficult to cultivate in pure culture, but they are readily available in the mixed culture of effluents from the anaerobic degradation of organic matter, i.e. the fermentation effluent of biogas plants. The rate-limiting step in the work of CH4-forming microbial communities is the low solubility of H2 in the aqueous environment. In our approach, the simple fed-batch fermentation technique was selected to supply the gaseous substrates for the microbial community at laboratory scale and mesophilic temperature. Periodically withdrawn samples were analyzed for process parameters and the microbial communities were studied using Terminal Restriction Fragment Length Polymorphism (T-RFLP) of the mcrA gene and Ion Torrent whole metagenome DNA sequencing. The metagenome data were evaluated by both read-based and genome-centric bioinformatics tools. The rearrangements in the mixed microbial communities, triggered by switching the operating conditions to biological power-to-biomethane (bio-P2M), have been established. The production rates were 6.30 mL CH4 L-1 h-1 during the acclimation phase and 9.21 mL CH4 L-1 h-1 by the fully adapted community, respectively. The diversity of the anaerobic microbiota decreased as the bio-P2M process progressed. Feeding the community with H2 apparently promoted the abundance of several genera, in particular Candidatus Cloacimonas and Herbinix. The diversity of the Archaea community decreased considerably upon daily feeding with H2 and CO2. The predominant Archea genus was Methanobacterium in every reactor, Methanothrix persisted for the first 4 weeks, while the initially less abundant genus Methanoculleus gained advantage during the adaptation to the sustained bio-P2M process. The accumulation of acetate indicated a strong involvement of homoacetogenic bacteria.

Study of physiological and biochemical responses to freezing stress in pomegranate (Punica granatum L.) trees during acclimation and deaclimation cycle

ABSTRACTChanges in freezing tolerance of four pomegranate (Punica granatum L.) cultivars, including ‘Alak Torsh’ (AT), ‘Tabestaneh Torsh’ (TT), ‘Poostsefid Torsh’ (PT), and ‘Poostsyah Shirin’ (PS), and its correlation with physiological and antioxidant responses were investigated in shoot samples during cold acclimation and deacclimation. Half part of shoot samples exposed to controlled freezing temperatures (−11,-14, and −17ºC) to determine lethal temperature (LT50) values based on relative electrolyte leakage method, and the other part was used for measuring physiological parameters at each time-point from September 2016 to March 2017. Totally, seasonal patterns were similar in four cultivars and their freezing tolerance changed depending on air temperatures and acclimation state alteration. In pomegranate shoots, LT50 values showed a positive correlation with MDA, starch, and antioxidant enzyme activity and a negative correlation with soluble carbohydrates, proline, and total phenolic content. The highest SOD, POD, and PPO activity for countering the stressful effect of low temperatures during acclimation and deacclimation, and the highest osmoregulant and total phenolic content coincided with the maximum cold hardiness in mid-winter. Of all studied cultivars, ‘PS’ started the acclimation phase later, but it showed the highest freezing tolerance (−16.98ºC) in mid-winter and resisted entering deacclimation phase to a greater extent (−15ºC).

Wintertime photosynthesis and spring recovery of Ilex aquifolium L.

Abstract: Former studies using the chlorophyll fluorescence technique on evergreen Ilex aquifolium L. showed that its photosynthetic potential for electron transport in winter recovers quickly when exposed to more favorable conditions. Since little is known, however, about its photosynthetic carbon gain in winter, we investigated its leaf gas exchange over an entire winter and spring period. Measurements were made rotationally in the field and in the laboratory to also investigate if I. aquifolium profits from warmer phases during winter in terms of net carbon gain. From the end of autumn until the end of spring, three different climate-driven phases of photosynthetic responses could be distinguished: first, an acclimation phase which lasted until February and was characterized by a gradually decreasing light-saturated gross photosynthesis (Amax(gross)), decreasing apparent quantum yield of CO2-assimilation (ΦΦi) and a decreasing ability of these parameters to recover overnight inside the laboratory. At the same time, maximal quantum yield of PSII (Fv/Fm) could fully regenerate. In this phase, single warmer days had a positive effect on carbon assimilation. Second, a phase of relatively constant but low photosynthesis which was virtually unaffected by temperature, lasting for almost two months occurred. Here, Amax(gross) and Φi had lost their ability to recover from winter conditions in the field, while Fv/Fm was much less affected. I. aquifolium was still able to conduct positive light-saturated net photosynthesis at a leaf temperature of -0.5 °C, but during this time it could not profit from milder temperatures in terms of carbon gain. Third, a phase of increasing photosynthesis (spring recovery) occurred, starting in March when the 5-day average temperature was above 5 °C and radiation in the field increased, and where all parameters slowly recovered from winter depressions. Our findings show that I. aquifolium is photosynthetically active over the whole winter, even at temperatures around 0 °C. In terms of carbon gain, however, I. aquifolium does not profit from warmer phases during winter, despite the fast recovery seen in chlorophyll fluorescence measurements.

Microbial community dynamics during aerobic granulation in a sequencing batch reactor (SBR).

Microorganisms in aerobic granules formed in sequencing batch reactors (SBR) remove contaminants, such as xenobiotics or dyes, from wastewater. The granules, however, are not stable over time, decreasing the removal of the pollutant. A better understanding of the granule formation and the dynamics of the microorganisms involved will help to optimize the removal of contaminants from wastewater in a SBR. Sequencing the 16S rRNA gene and internal transcribed spacer PCR amplicons revealed that during the acclimation phase the relative abundance of Acinetobacter reached 70.8%. At the start of the granulation phase the relative abundance of Agrobacterium reached 35.9% and that of Dipodascus 89.7% during the mature granule phase. Fluffy granules were detected on day 43. The granules with filamentous overgrowth were not stable and they lysed on day 46 resulting in biomass wash-out. It was found that the reactor operation strategy resulted in stable aerobic granules for 46 days. As the reactor operations remained the same from the mature granule phase to the end of the experiment, the disintegration of the granules after day 46 was due to changes in the microbial community structure and not by the reactor operation.

Weighted Gene Co-expression Network Analysis (WGCNA) Reveals the Hub Role of Protein Ubiquitination in the Acquisition of Desiccation Tolerance in Boea hygrometrica.

Boea hygrometrica can survive extreme drought conditions and has been used as a model to study desiccation tolerance. A genome-wide transcriptome analysis of B. hygrometrica showed that the plant can survive rapid air-drying after experiencing a slow soil-drying acclimation phase. In addition, a weighted gene co-expression network analysis was used to study the transcriptomic datasets. A network comprising 22 modules was constructed, and seven modules were found to be significantly related to desiccation response using an enrichment analysis. Protein ubiquitination was observed to be a common process linked to hub genes in all the seven modules. Ubiquitin-modified proteins with diversified functions were identified using immunoprecipitation coupled with mass spectrometry. The lowest level of ubiquitination was noted at the full soil drying priming stage, which coincided the accumulation of dehydration-responsive gene BhLEA2. The highly conserved RY motif (CATGCA) was identified from the promoters of ubiquitin-related genes that were downregulated in the desiccated samples. An in silico gene expression analysis showed that the negative regulation of ubiquitin-related genes is potentially mediated via a B3 domain-containing transcription repressor VAL1. This study suggests that priming may involve the transcriptional regulation of several major processes, and the transcriptional regulation of genes in protein ubiquitination may play a hub role to deliver acclimation signals to posttranslational level in the acquisition of desiccation tolerance in B. hygrometrica.

Electricity production and treatment of high-strength dairy wastewater in a microbial fuel cell using acclimated electrogenic consortium

Microbial fuel cells are innovative technologies that can efficiently remove chemical oxygen demand and biochemical oxygen demand, while simultaneously generating electricity, with a minimal environmental footprint. High efficiencies have recently been achieved for the treatment of low-strength wastewater. However, in treatment of a real high-strength wastewater, such as dairy effluent, the efficiency decreases drastically due to operational instability associated with environmental fluctuations, difficulty of maintaining the run for long periods, and fouling. In order to overcome these issues, a new initialization method was developed, with a start-up phase employing an inoculum composed of a consortium of fermenting and metal-reducing bacteria, followed by acclimation and treatment phases. The protocol employed enabled removal of 90% of total biochemical oxygen demand, 62% of total chemical oxygen demand, 72% of total Kjeldahl nitrogen, 71% of sodium, and 65% of ultraviolet absorbing substances from dairy wastewater. Furthermore, the microbial fuel cell produced maximum power densities of 1.45 W/m3 in the acclimation phase and 1.32 W/m3 in the treatment phase. The findings demonstrated that microbial fuel cells powered by real high-strength dairy wastewater can achieve high efficiencies.

SUN-097 AgRP Neurons Determine Survival in Activity-Based Anorexia Model

Anorexia Nervosa (AN) is an eating disorder characterized by severe hypophagia, high levels of physical activity, harsh weight loss and an intense fear of weight gain. It has the highest mortality rate among psychiatric illnesses and, due to the unknown underlying neurobiology, it is challenging to treat. Agouti-related protein (AgRP) neurons, which are localized in the arcuate nucleus in the hypothalamus, are both necessary and sufficient or feeding in adult animals.To uncover new neural circuits that may contribute towards vulnerability to AN or might be affected by AN, we employed the specific diphtheria toxin receptor-expressing mice (AgRP-DTR) which, by the selective ablation of AgRP neurons, allow to test the impact of an impaired AgRP circuit function under the activity-based anorexia (ABA) paradigm. ABA is a bio-behavioral phenomenon described in rodents and refers to the weight loss, hypophagia and paradoxical hyperactivity that develops in rodents exposed to running wheels and restricted food access, and provides a model for the key symptoms of AN. Mice that express DTR only in AgRP neurons and subcutaneously injected with diphtheria toxin (DTX) at postnatal day 3 lost more than 50% of AgRP neurons on postnatal day 7 compared to control. The same percentage of neuronal loss was detected in 8 weeks old mice. In addition, the neonatal animals developed normally after AgRP ablation, did not show any phenotypic effects and maintained normal food intake and weight when fed ad libitum. On postnatal day 36 (P36), males and females animals were housed with access on a running wheel and fed ad libitum for 4 days (acclimation phase). On P40, for 72 hours animals were fed for only two hours daily. Following the fasting phase, free access to food was returned and the running wheel was removed. Continuous multi-day analysis of running wheel activity showed that both controls and AgRP-DTR mice kept constant weight and food intake during acclimation. In contrast, although mice became hyperactive within the 24 hours following the onset of food restriction (FR), we noted a 10% mortality on day 2 and 70% mortality at day 4 among the AgRP DTR mice. Moreover, the survived AgRP-DTR mice failed to return to normal food intake and weight even when ad libitum food was provided. Overall, AgRP neurons showed to be crucial for the full development of ABA symptoms. The results suggest that our new experimental setting is able to correlate particular neurons populationto vulnerability, onset and progression of anorexia nervosa.

Development of aerobic granular sludge under tropical climate conditions: The key role of inoculum adaptation under reduced sludge washout for stable granulation

Aerobic granular sludge (AGS) is a promising technology for wastewater treatment. However, the success of the process depends on the formation of stable granular biomass, which is associated with the microbiological aspects of the sludge and reactor operating conditions. In this study, the development of AGS from a poor nitrifying flocculent sludge obtained in a sewage treatment plant designed only for organic matter removal was assessed in a sequencing batch reactor (SBR) under tropical climate conditions (temperatures of 28 ± 4 °C). The results showed that, despite the alternating anaerobic-aerobic conditions during the granules selection phase under high sludge washout rates (low settling time), readily biodegradable organic matter was mainly removed aerobically. The formed granules were unstable, exhibiting a substantial amount of filaments and pasty consistency. The biomass characteristics (e.g., sludge volume index, density, diameter and settling velocity) were negatively impacted as complete granulation was reached, while biomass loss and degranulation became inevitable. Poor nitrification and no enhanced biological phosphate removal (EBPR) were observed. Implementation of a new operational strategy incorporating an adaptation of the seed sludge under reduced washout conditions (high settling time) prior to the granules selection stage enabled most of the influent organics to be removed anaerobically. Besides allowing a feast-famine regime to be established in the reactor, the sludge acclimation phase favoured the development of slow-growing organisms and suppressed the appearance of filamentous-like structures. Fast-settling granules with regular shape remained stable in the long-term, while high ammonium (>95%) and total nitrogen removal (>90%) was obtained. However, EBPR activity was very unstable, most likely due to the high temperatures. The findings of this study are important for the spreading of the AGS technology worldwide, especially in developing countries where the conditions are different in all aspects.

Temperature and De‐icing Salt, Effect on the Activated Sludge Respiration

The respiratory activity of microorganisms in sewage sludge is affected by several physicochemical factors, and a considerable amount of information concerning the influence of individual factors has been recorded. However, very little is known about their effects in combination. In the recent past, the concentration of chlorides entering wastewater has increased greatly and the major source is sodium chloride, which is used in large quantities to de‐ice roads in winter. In this article, the effects of various concentrations of sodium chloride at different temperatures on the respiratory activity of the microorganisms have been examined. It is found that low temperature (6°C) and high concentrations of NaCl (1 M) had drastic effects on the metabolism of the microorganisms in activated sludge; the acclimation phase of activated sludge is 117 h. Not only is their respiratory activity strongly depressed but also the length of their acclimation period is greatly magnified.

Transcriptomic analysis by RNA-seq of Escherichia coli O157:H7 response to prolonged cold stress

The adaptability of Escherichia coli O157:H7 to different environmental stresses, including prolonged cold stress, poses a threat to food safety. In order to elucidate the prolonged cold response in E. coli O157:H7, genes related to prolonged coldresistance and their expression changes in E. coli O157:H7 ATCC35150 were screened and identified by analyzing their transcriptomedifferences between normal (37 °C) and low temperature storage (4 °C or −20 °C, 10 d), using RNA-sequencing. According to our results, 425 differentially expressed genes (DGEs) were identified responding to cold stresses in this study. Gene rpoS was significantly up-regulated (more than two fold; p < 0.05) and was referred to be the critical switch for the whole regulation in the response to prolonged cold stress. Moreover, cold shock genes played an important role only in the acclimation phase of E. coli O157:H7 in the early stage of cold stress, and were down-regulated in the adaptation stage. Specifically, E. coli O157:H7 would promote its resistance to prolonged cold stress mainly by increasing the expression of genes involved in the synthesis of unsaturated fatty acids and the accumulation of trehalose and betaine.

Performance study on organic carbon, total nitrogen, suspended solids removal and biogas production in hybrid UASB reactor treating real slaughterhouse wastewater

The performance of slaughterhouse wastewater treatment was studied in Hybrid Upflow Anaerobic Sludge Blanket Reactor (HUASBR) consisting of polypropylene media as attached growth surface. During acclimation phase, the amount of real slaughterhouse wastewater was gradually increased, whereas the amount of synthetic wastewater was proportionally decreased in a mixed feed to the reactor. The batch performance was evaluated by feeding 1000 ml of raw slaughterhouse wastewater and observing consistent Chemical Oxygen Demand (COD) removal over a batch period of 72 h. After attaining maximum COD removal efficiency and maximum methane gas production, the reactor was operated under continuous mode with gradually increasing Total Organic Carbon (TOC) loading rate. The reactor showed steady increase in the TOC removal efficiency as well as incremental biogas production. In this study, TOC loading rate was varied in the range of (1.12–14.19)kg TOC/m3/d corresponding to decremental Hydraulic Retention Time (HRT) of (24–6) hours. The HUASBR enhanced the TOC removal efficiency in slaughterhouse wastewater up to maximum of 95.85% under the TOC loading rate of 6.97 kg TOC/m3/d for 10 h HRT. The TSS removal efficiency was observed to be in the range of (72–98) % throughout the study. Similarly, The TN removal was also recorded between (48–78) % out of all the continuous operations. The maximum methane gas production rate was observed as 61.5 L/d at 10 h HRT.

Chronic impact of sulfamethoxazole: how does process kinetics relate to metabolic activity and composition of enriched nitrifying microbial culture?

AbstractBACKGROUNDThis study investigated utilization kinetics of ammonia‐nitrogen induced by chronic sulfamethoxazole (SMX) exposure on biomass with an enriched nitrifying community. A lab‐scale activated sludge system was supplied with 100 mg COD L‐1 of peptone mixture and 50 mg N L‐1 of ammonia nitrogen at a SRT of 15 days. At steady‐state, the reactor was operated with additional daily SMX dosing of 50 mg L‐1 for 35 days. Profiles of oxygen uptake rates and nitrogen fractions obtained in respirometric/batch experiments were used for estimation of nitrification kinetics.RESULTSAcute inhibitory impact of SMX was expressed with high levels of half saturation constants and endogenous decay rates. After 35 days, half saturation constants significantly increased while higher active biomass fractions and recovered endogenous decay rates were estimated. At the end of the acclimation phase, 92% nitrification was achieved with 10 mg L‐1 SMX utilization.CONCLUSIONInterpretation of modeling results with the outcomes of molecular analysis facilitated explanation of autotrophic/heterotrophic bacteria behavior in the course of SMX exposure. Removal of SMX may be attributed to co‐metabolism with ammonia oxidation and/or activity of SMX utilizing heterotrophic bacteria. © 2017 Society of Chemical Industry