Behavioral toxicity, histopathological alterations and oxidative stress in Tubifex tubifex exposed to aromatic carboxylic acids- acetic acid and benzoic acid: A comparative time-dependent toxicity assessment.

This study evaluated Acetic acid (AA) and Benzoic acid's (BA) acute and sublethal toxicity by observing mortality, behavioral responses, and changes in the levels of oxidative stress enzymes in Tubifex tubifex. Exposure-induced changes in antioxidant activity (Catalase, Superoxide dismutase), oxidative stress (Malondialdehyde concentrations), and histopathological alterations in the tubificid worms were also noted across exposure intervals. The 96 h LC50 values of AA and BA to T. tubifex were 74.99 and 37.15 mg/l, respectively. Severity in behavioral alterations (including increased mucus production, wrinkling, and reduction in clumping) and autotomy showed concentration-dependent trends for both toxicants. Although histopathological effects also showed marked degeneration in the alimentary and integumentary systems in highest exposure groups (worms exposed to 14.99 mg/l for AA and 7.42 mg/l for BA) for both toxicants. Antioxidant enzymes (catalase and superoxide dismutase) also showed a marked increase of up to 8-fold and 10-fold for the highest exposure group of AA and BA respectively. While species sensitivity distribution analysis revealed T. tubifex as most sensitive to AA and BA compared to other freshwater vertebrates and invertebrates, General Unified Threshold model of Survival (GUTS) predicted individual tolerance effects (GUTS-IT), with slower potential for toxicodynamic recovery, as a more likely pathway for population mortality. Study findings demonstrate BA with greater potential for ecological effects compared to AA within 24 h of exposure. Furthermore, ecological risks to critical detritus feeders like T. tubifex may have severe implications for ecosystem services and nutrient availability within freshwater habitats.

Techno-Economic Analysis of Producing Glacial Acetic Acid from Poplar Biomass via Bioconversion.

Most of the current commercial production of glacial acetic acid (GAA) is by petrochemical routes, primarily methanol carbonylation. GAA is an intermediate in the production of plastics, textiles, dyes, and paints. GAA production from biomass might be an economically viable and sustainable alternative to petroleum-derived routes. Separation of acetic acid from water is a major expense and requires considerable energy. This study evaluates and compares the technical and economic feasibility of GAA production via bioconversion using either ethyl acetate or alamine in diisobutylkerosene (DIBK) as organic solvents for purification. Models of a GAA biorefinery with a production of 120,650 tons/year were simulated in Aspen software. This biorefinery follows the path of pretreatment, enzymatic hydrolysis, acetogen fermentation, and acid purification. Estimated capital costs for different scenarios ranged from USD 186 to 245 million. Recovery of GGA using alamine/DIBK was a more economical process and consumed 64% less energy, due to lower steam demand in the recovery distillation columns. The estimated average minimum selling prices of GGA were USD 756 and 877/ton for alamine/DIBK and ethyl acetate scenarios, respectively. This work establishes a feasible and sustainable approach to produce GGA from poplar biomass via fermentation.

An interim internal Threshold of Toxicologic Concern (iTTC) for chemicals in consumer products, with support from an automated assessment of ToxCast™ dose response data.

Additional non-animal methods are urgently needed to meet regulatory and animal welfare goals. TTC is a broadly used risk assessment tool. TTC based on external dose has limited utility for multi-route exposure and some types of structure activity relationship assessments. An internal TTC (iTTC), where thresholds are based on blood concentration, would extend the applicability of TTC. While work is on-going to develop robust iTTC thresholds, we propose an interim conservative iTTC. Specifically, an interim iTTC of 1 µM, supported by the published experience of the pharmaceutical industry, a literature review of non-drug chemical/receptor interactions, and analysis of ToxCast™ data. ToxCast™ data were used to explore activity versus the 1 µM interim iTTC and recommendations for the analysis and interpretation of HTS data. Test concentration-based points of departure were classified to identify quality of fit to the Hill Model. We identified, for exclusion from the approach, estrogen receptor and androgen receptor targets as potent chemical/receptor interactions potentially associated with low dose exposure to non-pharmaceutical active ingredients in addition to the original TTC exclusions. With these exclusions, we conclude that a 1 µM plasma concentration is unlikely to be associated with significant biological effects from chemicals not intentionally designed for biological activity.

Assessment of inoculating various epiphytic microbiota on fermentative profile and microbial community dynamics in sterile Italian ryegrass.

AIMS: To evaluate the effects of various epiphytic microbiota from Italian ryegrass (IR), maize (MZ) and sorghum (SG) on fermentative profile and microbial community dynamics in sterile IR. METHODS AND RESULTS: Using microbiota transplantation, the irradiated IR was treated with the following: (i) sterile water; (ii) epiphytic microbiota on IR (IRIR); (iii) epiphytic microbiota on MZ (IRMZ); (iv) epiphytic microbiota on SG (IRSG). After 60 days of ensiling, MZ and SG microbiota significantly (P < 0·05) decreased lactic acid (LA) and acetic acid (AA) concentrations compared to IR microbiota, while SG microbiota notably (P < 0·05) reduced the ratio of LA to AA than MZ and IR microbiota. Apparently (P < 0·01) higher amounts of Lactobacillus genus were observed in IRIR and IRMZ groups on 60 day compared to IRSG group, and the dominant Lactococcus genus on 3 day was eventually replaced by Enterobacteriaceae and Lactobacillus in IRSG group. CONCLUSIONS: Exogenous microbiota could evidently affect the fermentative profile and microbial community dynamics of IR silage. The numbers of Enterobacteriaceae and Lactobacillus were mainly responsible for this. SIGNIFICANCE AND IMPACT OF THE STUDY: Identifying the role of microbe during ensiling is of great significance to manipulate the fermentation products and improve the preservation of silage.

Mutated fabG gene encoding oxidoreductase enhances the cost-effective fermentation of jasmine rice vinegar in the adapted strain of Acetobacter pasteurianus SKU1108.

A low-nutrient adapted strain, Acetobacter pasteurianus G-40, was successfully obtained by repetitive cultivation of A. pasteurianus 7E-13 under selective pressure. The adapted strain could grow well and produce 3.45-fold higher amounts of acetic acid than 7E-13 in jasmine rice wine containing 6% ethanol at 37 °C in a shaking flask. The G-40 strain also exhibited higher amounts of acetic acid (5.16%) in 2-L jar fermentor compared with 7E-13, where the bio-conversion yield to acetic acid from ethanol was 71% and 55.5% in the adapted strain and parental strain, respectively. In addition, genome sequence analysis of G-40 revealed that the strain has mutations in the 6 genes, of which the fabG gene encoding oxidoreductase is largely mutated by the partial recombination with a highly homologous fabG homolog present in the large plasmid of the strain. Over-expression of the mutated fabG gene and also the replacement of the original fabG gene in the chromosome with the mutated one obviously enhanced growth and acetic acid production of 7E-13 in the rice wine without any nutrient supplementation, indicating that the mutation in the fabG gene is mainly involved in higher fermentation ability under low-nutrient conditions. Thus, the results suggest that the adapted G-40 strain has proven useful for the cost-effective fermentation of rice vinegar.

Assessment of the physicochemical properties and bacterial composition of Lactobacillus plantarum and Enterococcus faecium-fermented Astragalus membranaceus using single molecule, real-time sequencing technology.

We investigated if fermentation with probiotic cultures could improve the production of health-promoting biological compounds in Astragalus membranaceus. We tested the probiotics Enterococcus faecium, Lactobacillus plantarum and Enterococcus faecium + Lactobacillus plantarum and applied PacBio single molecule, real-time sequencing technology (SMRT) to evaluate the quality of Astragalus fermentation. We found that the production rates of acetic acid, methylacetic acid, aethyl acetic acid and lactic acid using E. faecium + L. plantarum were 1866.24 mg/kg on day 15, 203.80 mg/kg on day 30, 996.04 mg/kg on day 15, and 3081.99 mg/kg on day 20, respectively. Other production rates were: polysaccharides, 9.43%, 8.51%, and 7.59% on day 10; saponins, 19.6912 mg/g, 21.6630 mg/g and 20.2084 mg/g on day 15; and flavonoids, 1.9032 mg/g, 2.0835 mg/g, and 1.7086 mg/g on day 20 using E. faecium, L. plantarum and E. faecium + L. plantarum, respectively. SMRT was used to analyze microbial composition, and we found that E. faecium and L. plantarum were the most prevalent species after fermentation for 3 days. E. faecium + L. plantarum gave more positive effects than single strains in the Astragalus solid state fermentation process. Our data demonstrated that the SMRT sequencing platform is applicable to quality assessment of Astragalus fermentation.

Exploitation of acid-tolerant microbial species for the utilization of low-cost whey in the production of acetic acid and propylene glycol.

Whey from cheese and yoghurt production operations contains useful constituents such as whey protein and lactose. However, the separation and extraction processes are difficult and costly, and hence, whey has limited end user demand and is typically disposed of as waste. Treatment and disposal of these high BOD wastes are both energy intensive and expensive. However, improper disposal of these wastes can pollute surface and ground water resources. The use of these low or negative cost substrates for the production of value-added products such as acetic acid and propylene glycol (PG) is of great significance in changing overhead costs to revenue streams. The present study focuses on bioproduction of acetic acid and PG from whey lactose and whey powder containing lactose and protein as an alternative to high cost nutritive medium. It was found that Lactobacillus buchneri, an acid-tolerant bacterium, is able to ferment lactose at pH ~ 4.2 to low molecular weight compounds such as acetic acid and PG each at 25-30 g L-1 concentration when using lactose as a major carbon substrate. The typical molar ratio of acetic acid to PG was close to 1:1 at the end of fermentation. The productivity of acetic acid and PG was improved using a high cell density fermentation with cotton cheesecloth as an immobilization matrix. The use of whey powder with immobilized fermentation system showed a similar performance to that of cultures fed with pure lactose at pH 4.2, resulting in a 57% conversion of lactose in whey to acetate and PG in total, against a stoichiometric maximum of 72%.

Assessment of the contribution of cocoa-derived strains of Acetobacter ghanensis and Acetobacter senegalensis to the cocoa bean fermentation process through a genomic approach.

Acetobacter ghanensis LMG 23848(T) and Acetobacter senegalensis 108B are acetic acid bacteria that originate from a spontaneous cocoa bean heap fermentation process and that have been characterised as strains with interesting functionalities through metabolic and kinetic studies. As there is currently little genetic information available for these species, whole-genome sequencing of A. ghanensis LMG 23848(T) and A. senegalensis 108B and subsequent data analysis was performed. This approach not only revealed characteristics such as the metabolic potential and genomic architecture, but also allowed to indicate the genetic adaptations related to the cocoa bean fermentation process. Indeed, evidence was found that both species possessed the genetic ability to be involved in citrate assimilation and displayed adaptations in their respiratory chain that might improve their competitiveness during the cocoa bean fermentation process. In contrast, other properties such as the dependence on glycerol or mannitol and lactate as energy sources or a less efficient acid stress response may explain their low competitiveness. The presence of a gene coding for a proton-translocating transhydrogenase in A. ghanensis LMG 23848(T) and the genes involved in two aromatic compound degradation pathways in A. senegalensis 108B indicate that these strains have an extended functionality compared to Acetobacter species isolated from other ecosystems.

Acetification of rice wine by Acetobacter aceti using loofa sponge in a low-cost reciprocating shaker.

AIMS: To maximize acetification rate (ETA) by adsorption of acetic acid bacteria (AAB) on loofa sponge matrices (LSM). METHODS AND RESULTS: AAB were adsorbed on LSM, and the optimal shaking rate was determined for maximized AAB growth and oxygen availability. Results confirm that the 1 Hz reciprocating shaking rate with 40% working volume (liquid volume 24 l, tank volume 60 l) achieved a high oxygen transfer coefficient (k(L)a). The highest ETA was obtained at 50% (w:v) LSM-AAB:culture medium at 30 ± 2°C (P ≤ 0·05). To test process consistency, nine sequential acetification cycles were run using LSM-AAB and comparing it with no LSM. The highest ETA (1·701-2·401 g l(-1) d(-1)) was with LSM-AAB and was associated with the highest biomass of AAB, confirmed by SEM images. CONCLUSIONS: Results confirm that LSM-AAB works well as an inert substrate for AAB. High oxygenation was maintained by a reciprocating shaker. Both shaking and LSM were important in increasing ETA. SIGNIFICANCE AND IMPACT OF THE STUDY: High cell biomass in LSM-AAB provides good conditions for higher ETAs of quick acetification under adequate oxygen transfer by reciprocating shaker. It is a sustainable process for small-scale vinegar production system requiring minimal set-up cost.

Model selection for microbial nutrient uptake using a cost-benefit approach.

We consider the uptake of various carbon sources by microorganisms based on four fundamental assumptions: (1) the uptake of nutrient follows a saturation characteristics (2) substrate processing has a benefit but comes at costs of maintaining the process chain (3) substrate uptake is controlled and (4) evolution optimized the control of substrate uptake. These assumptions result in relatively simple mathematical models. In case of two substrates, our main finding is the following: Depending on the overall topology of the metabolic pathway, three different behavioral patterns can be identified. (1) both substrates are consumed at a time, (2) one substrate is preferred and represses the uptake of the other (catabolite repression), or (3) a cell feeds exclusively on one or the other substrate, possibly leading to a population that splits in two sub-populations, each of them specialized on one substrate only. Batch-culture and retentostat data of toluene, benzoate, and acetate uptake by Geobacter metallireducens are used to demonstrate that the model structure is suited for a quantitative description of uptake dynamics.

Efficient production of pullulan using rice hull hydrolysate by adaptive laboratory evolution of Aureobasidium pullulans.

Pullulan production by Aureobasidium pullulans CCTCC M 2012259 using rice hull hydrolysate as the carbon source was conducted. The acetic acid in the hydrolysate was demonstrated to exert a negative effect on pullulan biosynthesis. Instead of employing expensive methods to remove acetic acid from the hydrolysate, a mutant A. pullulans ARH-1 was isolated following 20 cycles of adaptive laboratory evolution of the parental strain on medium containing acetic acid. The maximum pullulan production achieved by the adapted mutant at 48 h using the hydrolysate of untreated rice hull was 22.2 g L(-1), while that obtained by the parental strain at 60 h was 15.6 g L(-1). The assay of key enzymes associated with pullulan biosynthesis revealed that acetic acid inhibited enzyme activity rather than suppressing enzyme synthesis. These results demonstrated that adaptive evolution highly improved the efficiency of pullulan production by A. pullulans using the hydrolysate of untreated rice hull.

An economical biorefinery process for propionic acid production from glycerol and potato juice using high cell density fermentation.

An economically sustainable process was developed for propionic acid production by fermentation of glycerol using Propionibacterium acidipropionici and potato juice, a by-product of starch processing, as a nitrogen/vitamin source. The fermentation was done as high-cell-density sequential batches with cell recycle. Propionic acid production and glycerol consumption rates were dependent on initial biomass concentration, and reached a maximum of 1.42 and 2.30 g L(-1) h(-1), respectively, from 50 g L(-1) glycerol at initial cell density of 23.7 gCDW L(-1). Halving the concentration of nitrogen/vitamin source resulted in reduction of acetic and succinic acids yields by ~39% each. At glycerol concentrations of 85 and 120 g L(-1), respectively, 43.8 and 50.8 g L(-1) propionic acid were obtained at a rate of 0.88 and 0.29 g L(-1) h(-1) and yield of 84 and 78 mol%. Succinic acid was 13 g% of propionic acid and could represent a potential co-product covering the cost of nitrogen/vitamin source.

Assessment of gastric emptying function after gastrectomy using a real-time ¹³C breath test.

BACKGROUND/AIMS: Effectiveness of gastric emptying after pylorus-preserving gastrectomy (PPG) remains unclear and a method for continuous assessment is needed. We assessed post-PPG gastric emptying with a continuous real-time ¹³C breath test (BreathID system, Oridion, Israel). METHODOLOGY: Gastric emptying function was assessed by ¹³C breath test in 12 post-PPG patients and 9 post-distal gastrectomy (DG) patients. Continuous ¹³C-acetic acid breath test was performed using the BreathID system. Endoscopic study was also completed. RESULTS: Diarrhea was significantly less common in PPG than DG patients (p=0.021). No other questionnaire items and endoscopic findings showed a significant difference. In the ¹³C-acetic acid breath test, the gastric emptying coefficient (GEC) was significantly greater in PPG than DG patients (p=0.025). No other test parameters showed a significant difference. CONCLUSIONS: Emptying function in the remnant stomach was assessed successfully by the continuous ¹³C-acetic acid breath test. A greater GEC suggested better gastric emptying in PPG patients.

Enhanced growth of lactobacilli in soymilk upon immobilization on agrowastes.

Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. The objective of this study was to evaluate the effects of agrowastes from durian (Durio zibethinus), cempedak (Artocarpus champeden), and mangosteen (Garcinia mangostana) as immobilizers for lactobacilli grown in soymilk. Rinds from the agrowastes were separated from the skin, dried, and ground (150 microm) to form powders and used as immobilizers. Scanning electron microscopy revealed that lactobacilli cells were attached and bound to the surface of the immobilizers. Immobilized cells of Lactobacillus acidophilus FTDC 1331, L. acidophilus FTDC 2631, L. acidophilus FTDC 2333, L. acidophilus FTDC 1733, and L. bulgaricus FTCC 0411 were inoculated into soymilk, stored at room temperature (25 degrees C) and growth properties were evaluated over 168 h. Soymilk inoculated with nonimmobilized cells was used as the control. Utilization of substrates, concentrations of lactic and acetic acids, and changes in pH were evaluated in soymilk over 186 h. Immobilized lactobacilli showed significantly better growth (P < 0.05) compared to the control, accompanied by higher production of lactic and acetic acids in soymilk. Soymilk containing immobilized cells showed greater reduction of soy sugars such as stachyose, raffinose, sucrose, fructose, and glucose compared to the control (P < 0.05).

Assessment of myocardial metabolism in diabetic rats using small-animal PET: a feasibility study.

UNLABELLED: This feasibility study was undertaken to determine whether kinetic modeling in conjunction with small-animal PET could noninvasively quantify alterations in myocardial perfusion and substrate metabolism in rats. METHODS: All small-animal PET was performed on either of 2 tomographs. Myocardial blood flow and substrate metabolism were measured in 10 male Zucker diabetic fatty rats (ZDF, fa/fa) and 10 lean littermates (Lean, Fa/+) using (15)O-water, 1-(11)C-glucose, 1-(11)C-acetate, and 1-(11)C-palmitate. Animals were 12.0 +/- 1.4-wk old. RESULTS: Consistent with a type 2 diabetic phenotype, the ZDF animals showed higher plasma hemoglobin A(1c), insulin, glucose, and free fatty acid (FFA) levels than their lean controls. Myocardial glucose uptake (mL/g/min) was not significantly different between the 2 groups. However, higher glucose plasma levels in the ZDF rats resulted in higher myocardial glucose utilization (nmol/g/min) (Lean, 629 +/- 785, vs. ZDF, 1,737 +/- 1,406; P = 0.06). Similarly, myocardial FFA uptake (mL/g/min) was not significantly different between the 2 groups, (Lean, 0.51 +/- 28, vs. ZDF, 0.72 +/- 0.19; P = not significant) However, due to higher FFA plasma levels, utilization and oxidation (nmol/g/min) were significantly higher in the ZDF group (Lean, 519 +/- 462, vs. ZDF, 1,623 +/- 712, P < .001; and Lean, 453 +/- 478, vs. ZDF, 1,636 +/- 730, P < .01). CONCLUSION: Noninvasive measurements of myocardial substrate metabolism in ZDF rats using small-animal PET are consistent with the expected early metabolic abnormalities that occur in this well-characterized model of type 2 diabetes mellitus. Thus, small-animal PET demonstrates significant promise in providing a means to link the myocardial metabolic abnormalities that occur in rat of disease with the human condition.

Issues in cDNA microarray analysis: quality filtering, channel normalization, models of variations and assessment of gene effects.

We consider the problem of comparing the gene expression levels of cells grown under two different conditions using cDNA microarray data. We use a quality index, computed from duplicate spots on the same slide, to filter out outlying spots, poor quality genes and problematical slides. We also perform calibration experiments to show that normalization between fluorescent labels is needed and that the normalization is slide dependent and non-linear. A rank invariant method is suggested to select non-differentially expressed genes and to construct normalization curves in comparative experiments. After normalization the residuals from the calibration data are used to provide prior information on variance components in the analysis of comparative experiments. Based on a hierarchical model that incorporates several levels of variations, a method for assessing the significance of gene effects in comparative experiments is presented. The analysis is demonstrated via two groups of experiments with 125 and 4129 genes, respectively, in Escherichia coli grown in glucose and acetate.

Assessment of reductive acetogenesis with indigenous ruminal bacterium populations and Acetitomaculum ruminis.

The objective of this study was to evaluate the role of reductive acetogenesis as an alternative H2 disposal mechanism in the rumen. H2/CO2-supported acetogenic ruminal bacteria were enumerated by using a selective inhibitor of methanogenesis, 2-bromoethanesulfonic acid (BES). Acetogenic bacteria ranged in density from 2.5 x 10(5) cells/ml in beef cows fed a high-forage diet to 75 cells/ml in finishing steers fed a high-grain diet. Negligible endogenous acetogenic activity was demonstrated in incubations containing ruminal contents, NaH13CO3, and 100% H2 gas phase since [U-13C]acetate, as measured by mass spectroscopy, did not accumulate. Enhancement of acetogenesis was observed in these incubations when methanogenesis was inhibited by BES and/or by the addition of an axenic culture of the rumen acetogen Acetitomaculum ruminis 190A4 (10(7) CFU/ml). To assess the relative importance of population density and/or H2 concentration for reductive acetogenesis in ruminal contents, incubations as described above were performed under a 100% N2 gas phase. Both selective inhibition of methanogenesis and A. ruminis 190A4 fortification (>10(5) CFU/ml) were necessary for the detection of reductive acetogenesis under H2-limiting conditions. Under these conditions, H2 accumulated to 4, 800 ppm. In contrast, H2 accumulated to 400 ppm in incubations with active methanogenesis (without BES). These H2 concentrations correlated well with the pure culture H2 threshold concentrations determined for A. ruminis 190A4 (3,830 ppm) and the ruminal methanogen 10-16B (126 ppm). The data demonstrate that ruminal methanogenic bacteria limited reductive acetogenesis by lowering the H2 partial pressure below the level necessary for H2 utilization by A. ruminis 190A4.

The use of carbon 11-labeled acetate for assessment of aerobic metabolism.

Carbon 11-labeled acetate has been validated as a tracer of citric acid flux and indirectly of oxidative metabolism. 11C-labeled acetate is predominantly metabolized to 11C-labeled carbon dioxide, which clears from the heart. The myocardial 11CO2 efflux rate that can be estimated by dynamic positron emission tomographic imaging closely correlates with myocardial oxygen consumption over a wide range of flow, substrate use, and metabolic conditions. 11C-labeled acetate clearance rates are indirect indexes of oxidative metabolism. To provide absolute mass fluxes, the 11C-labeled acetate approach would require biochemical validation and configuration of a tracer kinetic model. Clinically, estimates of myocardial oxygen consumption appear to be useful in assessing tissue viability, as shown in patients after acute myocardial infarction or with chronic coronary artery disease. In non-coronary artery disease, 11C-labeled acetate may provide measurement of cardiac efficiency and be useful for monitoring therapy.