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The soil microbial carbon pump (MCP) is increasingly acknowledged as being directly linked to soil organic carbon (SOC) accumulation and stability. Given the close coupling of carbon (C) and nitrogen (N) cycles and the constraints imposed by their stoichiometry on microbial growth, N addition might affect microbial growth strategies with potential consequences for necromass formation and carbon stability. However, this topic remains largely unexplored. Based on two multi‐level N fertilizer experiments over 10 years in two soils with contrasting soil fertility located in the North (Cambisol, carbon‐poor) and Southwest (Luvisol, carbon‐rich), we hypothesized that different resource demands of microorganism elicit a trade‐off in microbial growth potential (Y‐strategy) and resource‐acquisition (A‐strategy) in response to N addition, and consequently on necromass formation and soil carbon stability. We combined measurements of necromass metrics (MCP efficacy) and soil carbon stability (chemical composition and mineral associated organic carbon) with potential changes in microbial life history strategies (assessed via soil metagenomes and enzymatic activity analyses). The contribution of microbial necromass to SOC decreased with N addition in the Cambisol, but increased in the Luvisol. Soil microbial life strategies displayed two distinct responses in two soils after N amendment: shift toward A‐strategy (Cambisol) or Y‐strategy (Luvisol). These divergent responses are owing to the stoichiometric imbalance between microbial demands and resource availability for C and N, which presented very distinct patterns in the two soils. The partial correlation analysis further confirmed that high N addition aggravated stoichiometric carbon demand, shifting the microbial community strategy toward resource‐acquisition which reduced carbon stability in Cambisol. In contrast, the microbial Y‐strategy had the positive direct effect on MCP efficacy in Luvisol, which greatly enhanced carbon stability. Such findings provide mechanistic insights into the stoichiometric regulation of MCP efficacy, and how this is mediated by site‐specific trade‐offs in microbial life strategies, which contribute to improving our comprehension of soil microbial C sequestration and potential optimization of agricultural N management. [ABSTRACT FROM AUTHOR]

Abstract Green lettuce (Lactuca sativa L.) is a popular leafy vegetable grown and consumed worldwide for its crisp texture and nutritional value. This study investigates the impact of different inorganic fertilizers on the growth and productivity of green lettuce, with the aim of determining the most effective fertilizers for producing vibrant green lettuce. The research was carried out at the Jaya Wijaya Research Centre, Faculty of Agriculture, Slamet Riyadi University, employing a randomized design with a single factor: the type of inorganic fertilizer. The experimental treatments included Nutrimax, NPK 25.7.7, and a control group, each replicated four times. Lettuce plants treated with Nutrimax exhibited superior performance across various metrics, including plant height (32.63 cm), leaf color intensity (3.25), leaf count (13.5 leaves), fresh weight (94.75 grams), and dry weight (5.33 grams). Statistical analysis using Analysis of Variance, followed by the Least Significant Difference test at a significance level of 5%, revealed a significant influence of fertilizer treatment on the growth and yield of green lettuce plants. The type of fertilizer applied significantly affected the growth and yield of green lettuce cultivated using a floating hydroponic system. The number of leaves on the plant directly impacted the fresh weight of the leafy vegetables. These findings can serve as a valuable guide for optimizing green lettuce cultivation practices to achieve maximum yields.

Sweet potato (Ipomoea batatas (L.) Lam.) has a potential to become a new field crop for higher latitudes. Sweet potato was cultivated for the first time in the fields of Estonia. During the study, the photosynthetic characteristics and yields of sweet potato cultivars 'Evangeline' and 'Covington' were investigated under fertilisation with two nitrogen (N) rates (0 and 100 kg ha-1 N) and various fertilisers in 2018, 2019 and 2021. Variation in fertiliser rate and composition had no effect on CO2 assimilation rate (A) and stomatal conductance (gs). The negative relationship between photosynthetic nitrogen use efficiency (PNUE) and intrinsic water-use efficiency (iWUE) among cultivars and treatments indicated that water availability could limit nutrient availability and ultimately reduce the potential yield in northern growing regions. The highest sweet potato tuber yield (t ha-1) was obtained from 'Evangeline' and 'Covington' at N0 in 2021. A comparison of yields of 2018 and 2021 experiments suggests that sweet potatoes can be grown in high latitudes. It can be concluded that depending on weather conditions, cultivars and soil properties, fertilisers can promote high plant productivity. Further studies should focus on sweet potato plants traits that enable the efficient use of nutrients and water during a short and potentially dry growing season. [ABSTRACT FROM AUTHOR]

Different strains of a microorganism growing in the same environment display a wide variety of growth rates and growth yields. We developed a coarse-grained model to test the hypothesis that different resource allocation strategies, corresponding to different compositions of the proteome, can account for the observed rate-yield variability. The model predictions were verified by means of a database of hundreds of published rate-yield and uptake-secretion phenotypes of Escherichia coli strains grown in standard laboratory conditions. We found a very good quantitative agreement between the range of predicted and observed growth rates, growth yields, and glucose uptake and acetate secretion rates. These results support the hypothesis that resource allocation is a major explanatory factor of the observed variability of growth rates and growth yields across different bacterial strains. An interesting prediction of our model, supported by the experimental data, is that high growth rates are not necessarily accompanied by low growth yields. The resource allocation strategies enabling high-rate, high-yield growth of E. coli lead to a higher saturation of enzymes and ribosomes, and thus to a more efficient utilization of proteomic resources. Our model thus contributes to a fundamental understanding of the quantitative relationship between rate and yield in E. coli and other microorganisms. It may also be useful for the rapid screening of strains in metabolic engineering and synthetic biology.

Objective: Mixed or high-yielding breeds of livestock need lipid resources in the diet to provide energy requirements. In order to increase fat consumption and improve its digestibility, the use of lysophospholipids is believed to have advantages. Moreover, the dietary inclusion of fat helps reduces the consumption of grains and prevents metabolic disorders such as acidosis while maintaining other conditions of gastrointestinal physiology. The current study was performed to investigate the effects of consumption of different levels of lysophospholipids on the performance, quantitative and qualitative traits of carcass, apparent digestibility, some blood parameters and liver enzymes in Afshari × Zell male fattening lambs. Materials and methods: In this study, 24 Afshari × Zell male lambs with an average weight of 29.85± 9.1 kg and age of 4 months were used. In this study, 24 Afshari × Zell male lambs with an average weight of 29.85± 9.1 kg and age of 4 months were used. The experiment was conducted in 4 treatments and six replications over 90 days. Experimental treatments were included: 1) control group without adding lysophospholipid in the diet and with diets containing lipid source, 2) treatment containing lipid source plus 0.25% lysophospholipid in the diet, 3) treatment containing lipid source plus 0.50% Lysophospholipid in the diet, 4) The treatment contained a lipid source plus the addition of 0.75% lysophospholipid in the diet. the diets were fed individually to animals. Results: The results showed that the addition of lysophospholipid supplement to the diet of fattening lambs had a significant effect on daily feed intake. The use of 0.75% lysophospholipid supplement increased feed intake (1590g / day). In the present study, the use of 0.75% of lysophospholipid supplement in the diet reduced the numerical value of feed conversion ratio, but this reduction was not significant. The final live weight was higher in the treatments of lysophospholipid supplementation than in the control group. Also, the group that received 0.75% of the lysophospholipid supplement had a higher final weight (54.20 kg) than the control group as well as other groups. Dry matter and crude protein digestibility were not significantly different in the experimental groups. However, the apparent digestibility of crude fat in all groups receiving lysophospholipid supplementation increased compared to the control (74, 73.72 and 75.12%). The digestibility of neutral detergent fiber (NDF) had increased in all groups that received lysophospholipid supplementation (68, 68.24 and 69.22%). However, the digestibility of acid detergent fiber (ADF) increased significantly (30.32%) only in the group that received 0.75% of lysophospholipid supplement. Experimental treatments did not affect the concentrations of serum glucose and crude protein in experimental animals. Also, serum urea, cholesterol, triglyceride, LDL and VLDL concentrations increased with lysophospholipid supplementation. However, the serum HDL concentration decreased. Moreover, experimental treatments had no effect on the concentration of liver enzymes in blood serum. Although the concentrations of alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase were numerically higher than the control group on day 90 in the groups receiving lysophospholipid supplementation, but this increase was not statistically significant. Conclusion: The overall result of the present study showed that growth performance as well as valuable carcass parts was improved by dietary inclusion of 0.75% lysophospholipid. The apparent digestibility of ether extract and NDF were the highest in treatment containing 0.75% lysophospholipid. Decreased blood cholesterol and urea nitrogen were observed in the group received 0.25% lysophospholipid supplement. [ABSTRACT FROM AUTHOR]

Refining the energetic costs of cellular maintenance is essential for predicting microbial growth and survival in the environment. Here, we evaluate a simple batch culture method to quantify energy partitioning between growth and maintenance using microcalorimetry and thermodynamic modeling. The constants derived from the batch culture system were comparable to those that have been reported from meta‐analyses of data derived from chemostat studies. The model accurately predicted temperature‐dependent biomass yield and the upper temperature limit of growth for Desulfovibrio alaskensis G20, suggesting the method may have broad application. An Arrhenius temperature dependence for the specific energy consumption rate, inferred from substrate consumption and heat evolution, was observed over the entire viable temperature range. By combining this relationship for specific energy consumption rates and observed specific growth rates, the model describes an increase in nongrowth associated maintenance at higher temperatures and the corresponding decrease in energy available for growth. This analytical and thermodynamic formulation suggests that simply monitoring heat evolution in batch culture could be a useful complement to the recognized limitations of estimating maintenance using extrapolation to zero growth in chemostats. [ABSTRACT FROM AUTHOR]

During the two successive seasons of 2018/2019 and 2019/2020 the feild experiment was conducted in Al- Aqwaz, Giza Governorate, aiming to study the effect of three planting dates (1st of December, 15th of December and 1st of January) and three irrigation regimes (50, 75 and 100% of the irrigation requirements for each of the selected planting date) on the vegetative growth, chlorophyll, tuber chemical composition (nitrogen, potassium, phosphorus and calcium), tuber yield and its quality parameters (specific gravity, dry matter, protein and starch). The results showed that there were significant effects for the treatments of planting dates and irrigation regimes on all of the studied characters, in both seasons of study. Also, the effect of irrigation regems was more pronounced comparing with the effect of plantting dates on studied characters. However, The planting on the first of December and/or the irrigation with 100% of the irrigation water requirements were the most satisfactory treatments for exhibiting the most favorable vegetative growth, highest yield as well as tuber quality for potato cv. Spunta planted in Al-Aqwaz, Giza Governorate or any other similar areas. [ABSTRACT FROM AUTHOR]

Cooperation in microbial communities via production of public goods is susceptible to social cheating, since selfish individuals that do not contribute to their synthesis but benefit from their production thrive in the presence of cooperators. This behavior has been observed in the laboratory using bacterial and yeast models. Moreover, growing evidence indicates that cheating is frequent in natural microbial communities. In the laboratory, social cheating can promote population collapse or "tragedy of the commons" when excessive. Nevertheless, there are diverse mechanisms that counteract cheating in microbes, as well as theoretical and experimental evidence that suggests possible beneficial roles of social cheaters for the microbial populations. In this mini review manuscript we compile and discuss such possible roles. [ABSTRACT FROM AUTHOR]

• The roles of colistin resistance-regulating two-component regulatory system (crrAB) were explored. • The crrAB-positive Klebsiella pneumoniae isolates showed higher survival rates in the early stages of exposure to high colistin concentration. • Contribution of crrAB to virulence was identified by serum resistance assay and Galleria mellonella larvae survival assay. • crrAB would provide advantages for Klebsiella pneumoniae survival by increasing the final growth yield and initial survival against colistin. Alternation of the colistin resistance–regulating two-component regulatory system (crrAB) is a colistin-resistance mechanism in Klebsiella pneumoniae (K. pneumoniae), but its role in bacteria is not fully understood. Twelve colistin-susceptible K. pneumoniae clinical isolates were included in this study: six crrAB -positive and six crrAB -negative. We deleted the crrAB genes from two crrAB -positive isolates and complemented them. We measured the growth yields by determining growth curves in lysogeny broth and minimal media with or without Fe2+. In vitro selection rates for colistin resistance were determined by exposure to colistin, and survival rates against high concentrations of colistin (20 mg/L) at the early stage of growth (20 min) were investigated. Virulence was determined using a serum bactericidal assay and Galleria mellonella larval infection. The presence of crrAB was not associated with colistin resistance and did not increase the in vitro selection rate of colistin resistance after exposure. The growth yield of crrAB -positive isolates was higher in lysogeny broth media and increased when Fe2+ was added to minimal media. The crrAB -positive isolates showed higher survival rates in the early stages of exposure to high colistin concentrations. Decreased serum resistance was identified in the crrAB -deleted mutants. More G. mellonella larvae survived when infected by crrAB -deleted mutants, and higher survival rates of bacteria were identified within the larvae infected with wild-type than crrAB -deletant isolates. Conclusion: Through rapid response to external signals, crrAB would provide advantages for K. pneumoniae survival by increasing the final growth yield and initial survival against colistin treatment. This may partly contribute to the bacterial virulence. [ABSTRACT FROM AUTHOR]

The currently accepted biochemistry and bioenergetics of ammonia-oxidizing bacteria (AOB) show an inefficient metabolism: only 53.8% of the energy released when a mole of ammonia is oxidised and less than two of the electrons liberated can be directed to the autotrophic anabolism. However, paradoxically, AOB seem to thrive in challenging conditions: growing readily in virtually most aerobic environment, yet limited AOB exist in pure culture. In this study, a comprehensive model of the biochemistry of the metabolism of AOB is presented. Using bioenergetics calculations and selecting the minimum estimation for the energy dissipated in each of the metabolic steps, the model predicts the highest possible true yield of 0.16 gBio/gN and a yield of 0.13 gBio/gN when cellular maintenance is considered. Observed yields should always be lower than these values but the range of experimental values in literature vary between 0.04 and 0.45 gBio/gN. In this work, we discuss if this variance of observed values for AOB growth yield could be understood if other non-considered alternative energy sources are present in the biochemistry of AOB. We analyse how the predicted maximum growth yield of AOB changes considering co-metabolism, the use of hydroxylamine as a substrate, the abiotic oxidation of NO, energy harvesting in the monooxygenase enzyme or the use of organic carbon sources. • The maximum growth yield of AOB is calculated and agrees with the experimental observations. • The TEEM2 and The Energy Dissipation methods have been found wanting in this case. • Changes in the growth yield function of different substrates are also calculated. • The relationship between AOB and heterotrophs is discussed. [ABSTRACT FROM AUTHOR]

We performed kinetic studies of the growth of sulfate-reducing bacteria (SRB) indigenous to the water in an oilfield in Japan. The SRB growth was most active in injection water supplemented with ethanol; therefore, the SRB inhabiting the injection water of the reservoir were assumed to grow predominantly by assimilating sulfate and ethanol and generating H2S. Based on this mechanism and the results of incubation experiments in the injection water, we derived numerical models that calculate the growth rate and H2S generation of the SRB under three variables (temperature, sulfate concentration, and ethanol concentration). [ABSTRACT FROM AUTHOR]

Copyright of Jornal of Al-Muthanna for Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Jornal of Al-Muthanna for Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An endophytic species of Micrococcus was isolated from Aloe vera leaf (syn. Aloe barbadensis) and screened for protease production with five other species of Micrococcus. Data indicated that endophytic Micrococcus aloeverae AE-6 MCC 2184 and Micrococcus yunnanensis DSM 21948 showed efficient protease production potential and secreted active protease at high salt (10%), temperature (40 °C) and in wide range of pH 8-10. Unlike M. yunnanensis DSM 21948, protease production by M. aloeverae AE-6 MCC 2184 was stringently controlled by pH. Protease induction study using different group of peptides, peptide carbohydrates and peptide macronutrient combinations showed variable response with both the organisms. Result indicated that the amount of protease was not directly related to cell biomass but it depends on nature of inducible peptides. In this study we also developed a modified agar-well assay for semi-quantitative data from large number of replicates. [ABSTRACT FROM AUTHOR]

Different strains of a microorganism growing in the same environment display a wide variety of growth rates and growth yields. We developed a coarse-grained model to test the hypothesis that different resource allocation strategies, corresponding to different compositions of the proteome, can account for the observed rate-yield variability. The model predictions were verified by means of a database of hundreds of published rate-yield and uptake-secretion phenotypes of Escherichia coli strains grown in standard laboratory conditions. We found a very good quantitative agreement between the range of predicted and observed growth rates, growth yields, and glucose uptake and acetate secretion rates. These results support the hypothesis that resource allocation is a major explanatory factor of the observed variability of growth rates and growth yields across different bacterial strains. An interesting prediction of our model, supported by the experimental data, is that high growth rates are not necessarily accompanied by low growth yields. The resource allocation strategies enabling high-rate, high-yield growth of E. coli lead to a higher saturation of enzymes and ribosomes, and thus to a more efficient utilization of proteomic resources. Our model thus contributes to a fundamental understanding of the quantitative relationship between rate and yield in E. coli and other microorganisms. It may also be useful for the rapid screening of strains in metabolic engineering and synthetic biology., Competing Interests: VB, DR, JG, TG, Hd No competing interests declared, (© 2023, Baldazzi et al.)

Partial cutting is thought to be an alternative to achieve sustainable management in boreal forests. However, the effects of intermediate harvest intensity (45%-80%) on growth remain unknown in black spruce (Picea mariana (Mill.) B.S.P.) stands, one of the most widely distributed boreal species with great commercial interest. In this study, we analysed the effect of three experimental shelterwood and one seed-tree treatments on tree radial growth in even-aged black spruce stands, 10 years after intervention. Our results show that radial growth response 8-10 years after cutting was 41% to 62% higher than in untreated plots, with stand structure, treatment, tree position relative to skidding trails, growth before cutting and time having significant interactions. The stand structure conditioned tree growth after cutting, being doubled in younger and denser stands. Tree spatial position had a pronounced effect on radial growth; trees at the edge of the skidding trails showed twice the increase in growth compared to interior trees. Dominant trees before cutting located close to the skidding trails manifested the highest growth response after cutting. This research suggests that the studied treatments are effective to enhance radial wood production of black spruce especially in younger stands, and that the edge effect must be considered in silvicultural management planning. [ABSTRACT FROM AUTHOR]

field experiment was conducted during winter (rabi) season of 2013-14 at Agronomy Research Farm of N. D. University of Agriculture & Technology, Kumarganj, Faizabad (U.P.) to study the "Effect of integrated nutrient management on the growth, yield and quality of wheat (Triticum aestivum L.)". Treatments consist of 12 levels of fertility were evaluated in a randomized block design. The plant height, dry matter accumulation, no. of effective tillers m-2 and grain yields were significantly higher under incorporation of 125% recommended dose of fertilizer + 25% N through vermicompost, however, test weight, nitrogen and protein content were shows no significant differences. [ABSTRACT FROM AUTHOR]

In living cells, growth is the result of coupling between substrate catabolism and multiple metabolic processes that take place during net biomass formation and cellular maintenance processes. A crucial parameter for growth evaluation is its yield, i.e. the efficiency of the transformation processes. The yeast Candida utilis is of peculiar interest since its mitochondria exhibit a complex I that is proposed to pump protons but also an external NADH dehydrogenase that do not pump protons. Here, we show that in C. utilis cells grown on non-fermentable media, growth yield is 30% higher as compared to that of Saccharomyces cerevisiae that do not exhibit a complex I. Moreover, ADP/O determination in C. utilis shows that electrons coming from internal NADH dehydrogenase go through proton pumping complex I, whereas electrons coming from external NADH dehydrogenases do not go through proton pumping complex I. Furthermore, we show that electron competition strictly depends on extra-mitochondrial NADH concentration, i.e. the higher the extra-mitochondrial NADH concentration, the higher the competition process with a right way for electrons coming from external NADH dehydrogenases. Such a complex regulation in C. utilis allows an increase in growth yield when cytosolic NADH is not plentiful but still favors the cytosolic NADH re-oxidation at high NADH, favoring biomass generation metabolic pathways. [ABSTRACT FROM AUTHOR]

In this work, the simultaneous degradation of BPA and cheese whey (CW) in semi-continuous activated sludge reactors was studied. The acclimation process and microbial growth on BPA, CW and BPA + CW were analyzed. In addition, the effect of increasing CW concentration on the BPA degradation by acclimated activated sludge was also studied. In order to reduce the factors involved in the analysis of the simultaneous degradation of BPA and CW, the effect of bisphenol A (BPA) on activated sludge not previously exposed to BPA (native activated sludge) was studied. Results demonstrate that BPA concentrations lower than 40 mg l had a negligible effect on the growth of native activated sludge. In the semi-continuous reactors, the presence of CW increased the acclimation time to 40 mg l of BPA. Once the capability of degrading BPA was acquired, the removal of BPA was not affected by the presence of CW. Increasing the CW concentration did not affect the removal of BPA by the acclimated activated sludge. Additionally, the CW consumption was not modified by the presence of BPA. Kinetic and stoichiometric coefficients reported in the present work can be useful in developing mathematical models to describe the simultaneous aerobic biodegradation of a biogenic substrate, such as CW, and BPA by activated sludge. [ABSTRACT FROM AUTHOR]

The article reflects on the complex relationship between microbial growth rate and yield and its implications on ecosystem. Topics discussed include fundamental traits of microbes, bacterial growth efficiency (BGE), and relationship between growth rate and yield in various environmental conditions and ecological strategies.

Partial cutting is thought to be an alternative to achieve sustainable management in boreal forests. However, the effects of intermediate harvest intensity (45%–80%) on growth remain unknown in black spruce (Picea mariana (Mill.) B.S.P.) stands, one of the most widely distributed boreal species with great commercial interest. In this study, we analysed the effect of three experimental shelterwood and one seed-tree treatments on tree radial growth in even-aged black spruce stands, 10 years after intervention. Our results show that radial growth response 8–10 years after cutting was 41% to 62% higher than in untreated plots, with stand structure, treatment, tree position relative to skidding trails, growth before cutting and time having significant interactions. The stand structure conditioned tree growth after cutting, being doubled in younger and denser stands. Tree spatial position had a pronounced effect on radial growth; trees at the edge of the skidding trails showed twice the increase in growth compared to interior trees. Dominant trees before cutting located close to the skidding trails manifested the highest growth response after cutting. This research suggests that the studied treatments are effective to enhance radial wood production of black spruce especially in younger stands, and that the edge effect must be considered in silvicultural management planning.

Abstract: In the present study phytoavailability of Cd, growth yield, cellular Cd accumulation and oxidative stress responses were studied in leafy vegetable Amaranthus caudatus under soil amendments. The test plant was cultivated in Cd contaminated soil (6ægCdg−1 soil) amended with different doses: 0.5, 2, 5 and 10 percent of rice husk (RH), saw dust (SD), farmyard manure (FYM), farmyard in combination with nitrogen, and phosphorus and potassium (FYM+NPK). Phytoavailability of Cd in amended soil and cellular Cd accumulation in edible parts (shoot) of A. caudatus declined maximally with 5 percent dose of each amendment, and decrease in Cd content in tissues was 36, 45, 23 and 14 percent under FYM, FYM+NPK, RH and SD amendments, respectively, over the value recorded in plants grown in Cd contaminated non-amended soil (Cd+NA soil). The shoot yield in control plant cultivated in the absence of Cd without amendment (Cd−NA soil) was 18.1ñ0.98gfwplant−1 and it was declined up to 50 percent (9.2ñ0.80gfwplant−1) when plants were grown in Cd+NA soil. Amendments with 5 percent doses of FYM+NPK and FYM enhanced the yield up to 26.5ñ0.57 and 20.5ñ1.00gfwplant−1, respectively, which may be correlated with better mineral nutrients and organic carbon content in amended soil. RH and SD amendments with similar doses improved in yield up to 16.9ñ0.43 and 15.2ñ0.45gfwplant−1, respectively, however, it was still less than that of control. Further, correlation analysis of growth yield, Cd concentration and oxidative stress under these conditions suggest that with the decrease in cellular Cd concentration following amendment the level of oxidative markers (oxidants: O2 − and H2O2 and lipid peroxidation: malondialdehyde; MDA) declined as a result of significant enhancement in the activity of enzymatic antioxidants (peroxidase, ascorbate peroxidase, superoxide dismutase, dyhydroascorbe reductase and catalase). Thus, the present technique can efficiently reduce the metal load in food chain and also increase plant yield, hence it could be applied in catchments area of urban cities where metal contamination has become an unavoidable factor. [ABSTRACT FROM AUTHOR]

Predicting metabolic rates and population sizes of microorganisms in natural environments is a central problem in geomicrobiology. Such predictions can be made on the basis of a thermodynamically consistent rate law that accounts for both kinetic and thermodynamic controls on microbial metabolism. Application of the rate law requires kinetic and growth parameters, the values of which have been determined for pure and mixed cultures growing in laboratory reactors. However, not all parameter values derived from laboratory studies can be validly applied to the environment. This article illustrates a best-choice approach for extrapolating experimentally-derived parameter values to natural environments, using microbial sulfate reduction coupled to acetate oxidation as an example. We compiled kinetic and growth parameters determined by previous laboratory studies and evaluated their applicability to natural environments. Our results suggest that some parameters, such as rate constants and maximum growth yields, can be applied directly to the environment; others, such as half-saturation constants and specific maintenance rates, are best determined using samples recovered from the environment of interest. The best-choice parameter values were applied to simulation of acetotrophic sulfate reduction in the sediments of a freshwater lake. Our analysis shows that the best-choice approach reduces the tasks of parameter fitting and simplifies the modeling exercise. The proposed approach also ensures that parameters in use are consistent with the physiology of indigenous microorganisms, and relevant to the environment of interest. [ABSTRACT FROM PUBLISHER]

Microbes save energy from the environment by synthesizing ATP. Understanding microbial energy conservation is important for both theoretical and practical applications. This paper focuses on the common metabolism of anoxic environments--ferric iron respiration, sulfate respiration, and methanogenesis--and analyzes microbial energy conservation on the basis of the thermodynamics as well as physiological models of respiratory reactions. The results of the analysis show that iron respiration synthesizes 1 to 4 ATPs by transferring eight electrons from H2, acetate, lactate, and ethanol to ferric minerals; sulfate respiration makes 0.25 to more than 3 ATPs by transferring eight electrons from the same suite of electron donors to sulfate; methanogenesis yields 0 to 1 ATP by oxidizing four H and by disproportionating one acetate. The ATP yields are compared to growth yields and energy thresholds of anaerobic metabolism to explore the impact of energy conservation. Specifically, energy conservation controls microbial growth: in geochemical systems, respiring microbes synthesize up to 5 g biomass per mole of ATP. Energy conservation also requires the environment to supply chemical energy at quantities greater than the energy saved by microbes. These results unify our view of microbial metabolism, and can be applied to evaluating the occurrence and significance of microbial life in natural environments. [ABSTRACT FROM AUTHOR]

Abstract: Biodegradation of resorcinol and p-cresol using fungus Gliomastix indicus MTCC 3869 was investigated in batch culture experiments at 28°C temperature and pH of 6 in the medium up to the initial concentration of 1300mg/L and 700mg/L for resorcinol and p-cresol, respectively. Five specific growth kinetic models and five specific degradation rate models were fitted to the experimental data in order to get best fitted kinetic models. The variation of observed growth yield and maintenance energy requirement with the initial substrate concentration was also studied. The model for maintenance energy coefficient was fitted to the experimental data. The model parameters were: m 1 =0.0135h−1, k =0.054, μ max =0.132h−1 for resorcinol and m 1 =0.0229h−1, k =0.011, μ max =0.102h−1 for p-cresol. Two mathematical models comprising of two sets of ODE were solved simultaneously to get degradation profiles with time. The model with varying growth yield and maintenance energy was found to be most appropriate biodegradation model. [Copyright &y& Elsevier]

Arbuscular mycorrhizal fungi (AMF) have the capability to improve crop yields by increasing plant nutrient supply. A pot experiment was conducted under natural conditions to determine the response of AMF inoculation on the growth of maize (Zea mays L.), sorghum (Sorghum bicolor L.), millet (Pennisetum glaucum L.), mash bean (Vigna mungo L.), and mung bean (Vigna radiata. L.) crops during 2008. The experiment was conducted as a completely randomized design in three replications using phosphorus (P)–deficient soil. Three plants were grown in 10 kg soil up to the stage of maximum growth for 70 days. Spores of AMF were isolated from rhizosphere of freshly growing wheat and berseem crops and mixed with sterilized soil with fine particles. Crops were inoculated in the presence of indigenous mycorrhiza with the inoculum containing 20 g sterilized soil mixed with 40–50 AMF spores. Inoculation with AMF improved yield and nutrient uptake by different crops significantly over uninoculated crops. Inoculated millet crop showed 20% increase in shoot dry matter and 21% in root dry matter when compared with other inoculated crops. Increases of 67% in plant nitrogen (N) and iron (Fe) were observed in millet, 166% in plant P uptake was observed in mash beans, 186% in zinc (Zn) was measured in maize, and 208% in copper (Cu) and 48% in manganese (Mn) were noted in sorghum crops. Maximum root infection intensity of 35% by AMF and their soil spore density were observed in millet crop followed by 32% in mash beans. Results suggest that inoculation of AMF may play a role in improving crop production and the varied response of different crops to fungi signifies the importance of evaluating the compatibility of the fungi and plant host species. [ABSTRACT FROM AUTHOR]

This study investigated the effects of 2,4-dichlorophenol on reduction of activated sludge in membrane bioreactors. Significant inhibition on sludge growth and slight reduction in COD removal were observed at higher 2,4-dichlorophenol dosages. The deviation between relative specific COD removal rate (q/q0) and relative specific growth rate (μ/μ0) suggested that a minimum 2,4-dichlorophenol concentration was required for uncoupling of anabolism and catabolism. With the increase of the dosage of 2,4-dichlorophenol, stepwise improvement of biomass bioactivity and the reduction in activated sludge production were achieved simultaneously. Compared with the control bioreactor, the peak distribution of floc size in the 2,4-dichlorophenol added bioreactor shifted to a range of smaller floc size. Besides, addition of 2,4-dichlorophenol caused little variation of microorganism community structure and SVI value of the sludge. After 24-hour operation, the residue 2,4-dichlorophenol concentration in the bioreactors was reduced to a negligible level. [ABSTRACT FROM AUTHOR]

Abstract: Cis-1,2-dichloroethene (cDCE) is a compound of concern at many chloroethene-contaminated sites, since it tends to accumulate during reductive dechlorination of the higher chlorinated ethenes. Stable carbon isotope fractionation during aerobic cDCE biodegradation was observed in groundwater microcosms under varying incubation conditions (room temperature/groundwater temperature; with/without inorganic nutrients), and resulted in an average stable carbon isotope enrichment factor of −15.2±0.5‰. A new enrichment culture, obtained from groundwater microcosms, degraded cDCE concentrations up to 100mgL−1, was active at temperatures between 4 and 23°C, had a pH optimum of ∼7, and could withstand prolonged periods (250d) of starvation. Microbial growth during degradation of cDCE as sole carbon and energy source was demonstrated by protein formation in mineral medium not containing any known auxiliary substrate. The obtained growth yield was 12.5±1.9g of proteinMol−1 of cDCE, with a doubling time of 53±2h at 23°C. Aerobic degradation of cDCE as sole carbon and energy source appears to be a promising biological process for site remediation. [Copyright &y& Elsevier]

Bioethanol made from lignocelluloses biomass resources, provides unique environmental, economic and strategic benefits, when compared to gasoline as automobile fuel. To be able to substitute gasoline by bioethanol, one should over come many obstacles, including the production of furfural and hydroxyl-methyl furfural, which are produced when cellulosic materials are treated in the presence of acids in high temperature and pressure to produce simple sugars. These inhibitory compounds have a profound negative effect on the growth of ethanol producing yeasts and their ethanol production. Saccharomyces cerevisiae Lalvin EC 111 8TM, an industrial ethanologenic strain, was used in media with high concentrations of furfural (i.e. 4, 5 and 6 g/L) to study the tolerance it shows against this compound. Results showed that both the amount of growth and ethanol production were decreased when furfural was present in the media. The amount of decrease was higher in the concentration of 6 g/L of furfural than 4 and 5 g/L. [ABSTRACT FROM AUTHOR]