Concentrations Of Octanoic Acid Research Articles

Semi‐continuous non‐sterile production of medium chain‐length polyhydroxyalkanoates from fatty acids

AbstractMedium chain‐length polyhydroxyalkanoates (mcl‐PHAs) are efficiently synthesized from fatty acids. It was hypothesized that under non‐axenic conditions, the anti‐microbial properties of fatty acids would reduce growth of microbial competitors and allow Pseudomonas putida LS46 to dominate the population resulting in non‐sterile mcl‐PHA production. Non‐sterile batch and fed‐batch cultures produced similar final mcl‐PHA content, monomer composition, and productivity during 24–27 h cultivations when compared to sterile control cultures for initial octanoic acid concentrations ranging from 5 to 40 mM at an initial pH of 6.5. In the absence of a P. putida inoculum, growth was eventually observed in non‐sterile medium after a lag period of up to 120 h, the length of which was dependent on the octanoic acid concentration. The efficacy of prolonged non‐sterile cultivation was tested using a sequential batch reactor (SBR). After 28 days (672 h), 1.62 g L−1 of total biomass was observed, of which the mcl‐PHA content was 47%. This resulted in a PHA titer of 0.77 g L−1, and a volumetric PHA productivity of 32 mg L−1 h−1. The polymer composition remained stable throughout at 87.0 ± 2.7% C8 monomers, and short‐chain length (scl‐) monomers were not detected. This study is the first of its kind to report that purely mcl‐PHAs were produced after prolonged periods in a non‐sterile environment and demonstrate that medium chain‐length fatty acids exert a strong selective pressure toward organisms that synthesize mcl‐PHA. This suggests an opportunity for mcl‐PHA production in open continuous cultivation, which could reduce both fixed and operating costs.

Octanoic acid-rich enteral nutrition attenuated hypercatabolism through the acylated ghrelin-POMC pathway in endotoxemic rats

ObjectivesMetabolic disorders and no response to intravenous nutrition because of sepsis have been urgent problems for clinical nutrition support. Enteral nutrition (EN) has been an important clinical therapeutic measure in septic patients; however, simple EN has not demonstrated good performance. This study aimed to investigate the effects of different concentrations of octanoic acid (OA)-rich EN on hypercatabolism in endotoxemic rats and test whether OA-rich EN could attenuate hypercatabolism through the acylated ghrelin-proopiomelanocortin (POMC) pathway. MethodsRats were randomly divided into six groups: sham, lipopolysaccharide (LPS), LPS + EN and LPS + EN + OA (0.25, 0.5, and 1 g/kg, respectively) groups to investigate the effects of different concentrations of OA-rich EN on hypercatabolism in endotoxemic rats. The rats were then randomly divided into four groups: sham, LPS, LPS + OA, and LPS + OA + Go-CoA-Tat, to test whether OA-rich EN attenuated hypercatabolism through the acylated ghrelin-POMC pathway. Rats received nutrition support via a gastric tube for 3 d (100 kcal/kg daily). Insulin resistance, muscle protein synthesis and atrophy, inflammatory cytokines, ghrelin in circulation and hypothalamus, ghrelin O-acyltransferase (GOAT), and the adenosine 5′-monophosphate-activated protein kinase (AMPK)-autophagy-POMC pathway were measured. ResultsCompared with simple EN, OA-rich EN promoted the acylation of ghrelin in a dose-dependent manner and attenuated POMC-mediated hypercatabolism in endotoxemic rats. Inhibition of GOAT activity decreased the level of acylated ghrelin and aggravated POMC-mediated hypercatabolism conferred by OA-rich EN. ConclusionsOA-rich EN could increase the level of acylated ghrelin and attenuate hypercatabolism through the acylated ghrelin-POMC pathway compared with simple EN in endotoxemic rats.

Treatment of food processing wastes for the production of medium chain fatty acids via chain elongation

The production of medium chain fatty acids (MCFAs) through reverse β-oxidation was investigated both on synthetic and real substrates. From preliminary batch tests emerged that caproic acid was maximized under an acetate/ethanol molar ratio of 5:1 at neutral pH. This ratio was then adopted in different semi-continuous tests operating with different amounts of the two reactants. It emerged that the MCFAs yield reached the maximum level of 6.7% when the total molar substrate amount was around 40–45 mmol/d, while the process was inhibited for values higher than 400 mmol/d. Semi-continuous tests using real waste as substrates, namely food waste condensate, cheese whey, and winery wastewater, confirmed the results obtained with the synthetic substrates. Better performances were obtained when an adequate molar ratio of the acetate and the electron-donor compound was naturally present. Therefore, a MCFAs yield of 25% and 10.5% was obtained for condensate of food waste and acidic cheese whey, respectively. Regarding MCFAs composition, caproic acid was the dominant form but small concentrations of octanoic acid were also found in the tests where ethanol was the electron donor (synthetic substrates and food waste condensate). Octanoic acid was not produced in test where lactic acid represented the electron donor molecules (cheese whey). Condensate and synthetic samples were dominated by Pseudoclavibacter caeni with an abundance of 38.19% and 33.38% respectively, while Thomasclavelia (24.13%) and Caproiciproducens (11.68%) was the most representative genus in acidic cheese whey sample.

Sugar-Induced Cell Death in the Yeast S. cerevisiae Is Accompanied by the Release of Octanoic Acid, Which Does Not Originate from the Fatty Acid Synthesis Type II Mitochondrial System

Incubation of the yeast S. cerevisiae with glucose, in the absence of other nutrients, leads to Sugar-Induced Cell Death (SICD), accompanied by the accumulation of Reactive Oxygen Species (ROS). Yeast acidifies the environment during glucose metabolism not only as a result of the activity of the H+-ATPase of the plasma membrane but also due to the release of carboxylic acids. Acetic acid is known to induce apoptosis in growing yeast. We analyzed the composition of the incubation medium and found octanoic acid (OA) but no other carboxylic acids. Its concentration (0.675 µM) was significantly lower than the one at which OA had a toxic effect on the cell. However, the theoretically calculated concentration of OA inside the cell (about 200 μM) was found to be high enough to lead to cell necrosis. To test the hypothesis that OA might cause SICD, we used a ΔACP1 strain incapable of synthesizing OA in the yeast mitochondrial Fatty Acid Synthesis type II system (FAS-II). The deletion of the ACP1 gene did not affect the OA content in the medium. But, on the other hand, OA is a precursor of lipoic acid, which has antioxidant properties. However, strains with deleted genes for lipoic acid biosynthesis from OA (ΔPPT2, ΔLIP2, ΔLIP5, and ΔSGV3) showed no change in ROS and SICD levels. Thus, lipoic acid synthesized in FAS-II does not protect cells from ROS accumulated during SICD. We conclude that OA synthesized in the mitochondrial FAS-II system and its derivative lipoic acid are not involved in SICD in yeast S. cerevisiae.

Transcriptomic and physiological analysis of the effect of octanoic acid on Meloidogyne incognita

Root knot nematodes are the most devastating root pathogens, causing severe damage and serious economic losses to agriculture worldwide. Octanoic acid has been reported as one of the nematicides, and its mode of action is not fully understood. The main objective of this study was to elucidate the effect of octanoic acid on Meloidogyne incognita by transcriptomic analysis combined with physiological and biochemical assays. In the toxicity assays with octanoic acid, the threshold concentration with nematicidal activity and the maximum concentration to which nematodes could respond were 0.03 μL/mL and 0.08 μL/mL respectively. Microscopic observation combined with protein and carbohydrates assays confirmed that the structure of the second-stage juveniles (J2s) was severely disrupted after 72 h of immersion in octanoic acid. Transcriptome analysis has shown that octanoic acid can interfere with the nematode energy metabolism, lifespan and signaling. Although the effects are multifaceted, the findings strongly point to the cuticle, lysosomes, and extracellular regions and spaces as the primary targets for octanoic acid. In addition, nematodes can withstand the negative effects of low concentration of octanoic acid to some extent by up-regulating the defense enzyme system and heterologous metabolic pathways. These findings will help us to explore the nematicidal mechanism of octanoic acid and provide important target genes for the development of new nematicides in the future.

Characterization of the key odorants of ripe Capparis spinosa L. fruit and changes in concentrations after storage by means of molecular sensory science

To characterize the key odorants in ripe Capparis spinosa L. fruit (RCF) and to investigate changes in the odorants after storage, volatiles were captured by both solid-phase microextraction and solvent extraction combined with solvent-assisted flavor evaporation; a total of 22 aroma-active regions were detected in the isolates by gas chromatography–olfactometry. Of 19 odor-active compounds identified positively, 13 odorants were found in RCF for the first time; their flavor dilution factors ranging from 1 to 512 were measured by an aroma extract dilution assay. Eleven odorants were determined as the key odorants by stable isotope dilution analysis, odor activity value (OAV) calculation, and recombination experiments. To further investigate the changes in odorants after storage, their concentrations and OAVs were determined. The results showed that the number of key odorants did not change before and after storage, but the concentrations of octanoic acid, sotolon, and 3-methylbutanoic acid increased markedly.

Use of ethanol extract of Chuanminshen Violaceum to inhibit the deterioration of frying oil

Influence of ethanol extract of Chuanminshen Violaceum (EEC) on the changes in physicochemical characteristics of soybean, rapeseed, and palm oils during frying was investigated. Composition analysis revealed that a total of 16 compounds with possible antioxidant activity were contained in the obtained EEC, such as bergaptol, curcumenol, viscutin, homobutein, nissolicarpin, and 4-hydroxyisopimpinellin. Similar to tert-butylhydroquinone (TBHQ), EEC inhibited the increases in acid value, carbonyl value, and total polar compound content of frying oil during frying. The decrease in content of polyunsaturated fatty acids and the increase in content of saturated fatty acids were also significantly inhibited in TBHQ-added or EEC-added oils. More than 45 % of the reduction in concentration of octanoic acid was obtained in EEC-added oils, which was comparable to those observed in TBHQ-added oils. Thermal oxidative degradation of polyunsaturated fatty acids was proven to be retarded by adding EEC and TBHQ to moderate the deterioration of frying oil. Thus, the potential use of EEC as a natural antioxidant was demonstrated to extend the usage life of vegetable oils with a high content of polyunsaturated fatty acids during frying.

Synergistic enhancement of fine-kaolinite-particle hydrophobic agglomeration by combining dodecylamine with octanoic acid

Because it is difficult to hydrophobically agglomerate fine kaolinite particles to obtain stronger, larger flocs using only dodecylamine (DDA) as a flocculant, octanoic acid (OA) was used as a synergistic flocculant to improve DDA-induced fine-kaolinite particle agglomeration. Particle settlement tests were conducted to study flocculation and synergistic flocculation behaviours of fine kaolinite particles for different DDA and/or OA concentrations. Results showed that OA strengthened DDA-induced particle agglomeration. Aggregate sedimentation rates and Stokes’ equivalent diameters exceeded 21.7 m/h and 84.4 µm, respectively. A clearer kaolinite suspension was obtained and a more compact aggregate layer accumulated within 3 min. Contact angles and Fourier-transform infrared (FTIR) spectroscopy were used to investigate kaolinite hydrophobicity before and after hydrophobisation and mechanisms of DDA and/or OA interactions with the kaolinite surface. Results suggested that faster sedimentation and larger equivalent-diameter aggregates were both related to significantly increased kaolinite-surface hydrophobicity. FTIR data confirmed that enhanced kaolinite surface hydrophobicity was owed to DDA and OA physisorption. The kaolinite micro-particle aggregation mechanism was analysed by SEM images. Kaolinite particle self-aggregation changed after OA was adsorbed on the kaolinite Si–O basal plane. Owing to DDA/OA synergistic effects, kaolinite particles hydrophobically agglomerated by actions of Al–O/Al–O and Al–O/Si–O faces, thereby promoting fine-kaolinite particle agglomeration and sedimentation. Study findings could lead to development of enhanced water-purification methods.

Correlation between Off-flavor and Morphology of Papaya (Carica papaya L.) Fruits

Aims: To investigate the correlation between fruit morphology and off-flavor characteristics which are naturally present in papaya.
 Place and Duration of Study: Department of Food Science and Technology (Sensory Laboratory and Food Analysis Services Laboratory), Centre for Tropical Horticulture Study (Chemistry Laboratory) and Indonesian Centre for Rice Research of Indonesian Agriculture Ministry (Flavor Laboratory), between December 2014 and September 2015.
 Methodology: Morphology descriptions of 6 papaya varieties, i.e. “Carisya”, “Callina”, “Sukma”, “Merah Delima”, “Burung” and “Bangkok”; off-flavor description using Quantitative Descriptive Analysis; semi-quantification of volatile compounds by using Headspace Solid-Phase Micro-Extraction and Gas Chromatography-Mass Spectrometry have been conducted.
 Results: The stinky-sour odor had positive correlation with the presence of butanoic acid (r=0.879) and octanoic acid (r=0.876). The stinky-sour odor had negative correlation with the weight (r= -0.836), length (r= -0.873), flesh thickness (r= -0.887), and ripe peel color (r= -0.838) in accordance to the octanoic acid content which showed negative correlation to fruit weight (r= -0.871), length (r= -0.830) and ripe peel color (r= -0.911). The stinky-sour odor as well as the concentration of butanoic and octanoic acid were most dominant in “Burung” and “Carisya” papayas. “Callina” and “Sukma” papayas had the weakest off- flavor intensity.
 Conclusion: The off-flavor perception of papaya was dominated by stinky-sour odor. The presence of octanoic acid might deliver synergism impact to butanoic acid in giving the perception of stinky-sour odor. High concentration of octanoic acid and strong intensity of stinky-sour odor were closely related to the small type of fruit weight (650 g or less), short size fruit (16.5 cm or less), thin flesh (less than 3 cm), and papaya varieties with orangish ripe peel color. These phenomena can be utilized in selection process in the field selection criteria to breed favorable papaya varieties.

A Yeast-Based Biosensor for Screening of Short- and Medium-Chain Fatty Acid Production.

Short- and medium-chain fatty acids (SMCFA) are important platform chemicals currently produced from nonsustainable resources. The engineering of microbial cells to produce SMCFA, however, lacks high-throughput methods to screen for best performing cells. Here, we present the development of a whole-cell biosensor for easy and rapid detection of SMCFA. The biosensor is based on a multicopy yeast plasmid containing the SMCFA-responsive PDR12 promoter coupled to GFP as the reporter gene. The sensor detected hexanoic, heptanoic and octanoic acid over a linear range up to 2, 1.5, and 0.75 mM, respectively, but did not show a linear response to decanoic and dodecanoic acid. We validated the functionality of the biosensor with culture supernatants of a previously engineered Saccharomyces cerevisiae octanoic acid producer strain and derivatives thereof. The biosensor signal correlated strongly with the octanoic acid concentrations as determined by gas chromatography. Thus, this biosensor enables the high-throughput screening of SMCFA producers and has the potential to drastically speed up the engineering of diverse SMCFA producing cell factories.

A Combined Computational and Experimental Study on the Polymerization of ε-Caprolactone

This paper reports the study on the synthesis of poly(e-caprolactone)—PCL by ring-opening polymerization (ROP) of e-caprolactone (CL) monomer with focus on mathematic developing of the growth mechanisms of polymer chain. Kinetics and mathematical modeling of ROP of CL was carried out to replicate the different experimental conditions. The computational results of conversion and molecular weight of the polymer were found to be comparable with the experimental results of nuclear magnetic resonance (NMR) spectroscopy and showed that the polymerization is highly dependent on the moisture (ROH). Moreover, parametric studies have shown how the concentrations of octanoic acid and catalyst affect the conversion and molecular weight of the polymer. The study here presented provides further understanding of synthesis of PCL, reporting mathematical models of PCL synthesis which can be used for predicting the characteristic of this biocompatible and biodegradable polymer.

Studies Regarding the Main Compositional Parameters and Some Volatile Compounds in Spirits from Iaşi Vineyard

The distillates obtained from wine, both raw and aged, are highly appreciated alcoholic beverages due to the refinement and fineness that characterizes them. Romania’s viticultural conditions are very favourable for these products - which in the last centuries have made regions such as Cognac and Armagnac in France famous. In Romania the aged distillate of wine is called “vinars” and in the Republic of Moldova it is named “divin”. This study analyses how the main compositional parameters and volatile compounds are influenced by the raw material wine, distillation technology, distillation steps, removal of the lower-quality fractions (heads and tails). The raw material used to make the distillates was a mixture of two wines of Fetească albă and Fetească regală, harvest of 2015, from Iasi vineyard. The proposed experimental protocol consisted of the double distillation of a volume of 1000 L of raw material. For the distillation, a simple copper distillery with a deflector was used. From each 10 L of distillate obtained, samples were taken and analysed via gas-chromatography.In the first and second distillation, the largest amounts of acetic acid are found in the head. The highest concentrations of octanoic acid are recorded in tails, as does hexanoic acid. The product obtained after the first distillation recorded an average alcoholic strength of 33.5% vol, which increased after the second distillation, so that the final distillate has an alcoholic strength of 58.5% vol. Concerning the acid profile, the following can be concluded: Acetic acid can be considerably diminished with the removal of the head fractions; Octanoic, hexanoic and decanoic acids fall into the class of short chain fatty acids, can affect the organoleptic qualities but are easily esterify the resulting compounds giving pleasing odour; aging in oak or mulberry wood barrels of crude distillates to achieve the maximum potential is recommended.

A Clostridium Group IV Species Dominates and Suppresses a Mixed Culture Fermentation by Tolerance to Medium Chain Fatty Acids Products.

A microbial community is engaged in a complex economy of cooperation and competition for carbon and energy. In engineered systems such as anaerobic digestion and fermentation, these relationships are exploited for conversion of a broad range of substrates into products, such as biogas, ethanol, and carboxylic acids. Medium chain fatty acids (MCFAs), for example, hexanoic acid, are valuable, energy dense microbial fermentation products, however, MCFA tend to exhibit microbial toxicity to a broad range of microorganisms at low concentrations. Here, we operated continuous mixed population MCFA fermentations on biorefinery thin stillage to investigate the community response associated with the production and toxicity of MCFA. In this study, an uncultured species from the Clostridium group IV (related to Clostridium sp. BS-1) became enriched in two independent reactors that produced hexanoic acid (up to 8.1 g L−1), octanoic acid (up to 3.2 g L−1), and trace concentrations of decanoic acid. Decanoic acid is reported here for the first time as a possible product of a Clostridium group IV species. Other significant species in the community, Lactobacillus spp. and Acetobacterium sp., generate intermediates in MCFA production, and their collapse in relative abundance resulted in an overall production decrease. A strong correlation was present between the community composition and both the hexanoic acid concentration (p = 0.026) and total volatile fatty acid concentration (p = 0.003). MCFA suppressed species related to Clostridium sp. CPB-6 and Lactobacillus spp. to a greater extent than others. The proportion of the species related to Clostridium sp. BS-1 over Clostridium sp. CPB-6 had a strong correlation with the concentration of octanoic acid (p = 0.003). The dominance of this species and the increase in MCFA resulted in an overall toxic effect on the mixed community, most significantly on the Lactobacillus spp., which resulted in a decrease in total hexanoic acid concentration to 32 ± 2% below the steady-state average. As opposed to the current view of MCFA toxicity broadly leading to production collapse, this study demonstrates that varied tolerance to MCFA within the community can lead to the dominance of some species and the suppression of others, which can result in a decreased productivity of the fermentation.

Differences in crystal growth behaviors of boehmite particles with octanoic acid and sodium octanoate under supercritical hydrothermal conditions

Crystal growth behaviors of boehmite particles with octanoic acid and sodium octanoate under supercritical hydrothermal condition were investigated. It was confirmed that adding carboxylic acid is effective in synthesizing hexagonal plate particles with high aspect ratios, while rhombic plate particles were obtained with nitric acid at similar pH condition. To investigate the modification under basic condition, sodium octanoate was used as the additive instead of octanoic acid. The increase in concentration of octanoic acid brought about high aspect ratio boehmite particles, while adding sodium octanoate resulted in low aspect ratio boehmite. Since the particles synthesized at more acidic condition were densely covered by octanoic acid, it is considered that the surface modification by octanoic acid was facilitated at such acidic condition. These results indicate that pH in the reaction field is one of the important factors to obtain the carboxylic acid modified boehmite particles with high aspect ratios, as well as other factors such as the carboxylic acid concentration and treatment time.

English

The aim of this study was to evaluate the effect of indigenous yeasts on the aroma of  fermented Chenin Blanc grape must by determining the volatile compounds, the odor activity value (OAV) and carrying out sensory analyses. The must, fermented by Hanseniaspora opuntiae/Saccharomyces cerevisiae combinations, presented higher concentrations of compounds such as ethyl acetate, ethyl hexanoate, 2-methyl-1-propanol and 2-phenylethanol, and a lower production of acids and acetaldehyde. This fermented must presented higher OAV values for compounds such as 2-methyl-1-propanol and ethyl acetate, 687.06 and 1264.16, respectively. 2-phenylethanol was produced by H. opuntiae and Hanseniaspora guilliermondii in combination with S. cerevisiae in amounts that resulted in OAV values of 5.63 and 4.62, respectively. In appropriate concentrations, these volatile compounds contribute positively to the aromatic quality of the fermented must. The highest mean acceptability and purchasing intention scores were obtained by the must fermented by H. opuntiae/S. cerevisiae. In the must fermented by H. guilliermondii/ S. cerevisiae, the absence of ethyl hexanoate and high concentrations of octanoic acid and acetaldehyde probably contributed to its low acceptability. Thus, it was suggested that the yeast genus Hanseniaspora in combination with S. cerevisiae, showed the potential to positively impact the wine aroma.   Key words: Non-Saccharomyces yeasts, volatile compounds, odor activity value, acceptability test, Hanseniaspora, “São Francisco Valley region”.

Establishment of a Gastric Cell-Based Assay System for Exploring Inhibitors of Octanoylated Ghrelin Production

Ghrelin, a gastric hormone, is a growth hormone-releasing peptide. Its serine-3 acylation with octanoic acid is essential for its orexigenic activity, and therefore, inhibition of the acylation of ghrelin may help in decreasing appetite and preventing obesity. This study aimed to establish a human gastric cell-based assay system to evaluate candidate inhibitors of octanoylated ghrelin production. In human gastric carcinoma AGS cells, obligatory factors for the posttranslational modification of ghrelin, such as certain prohormone convertases responsible for processing of proghrelin to the mature ghrelin and the enzyme-catalyzing acyl-modification of ghrelin, were well expressed, but ghrelin was expressed at low levels. Accordingly, we transfected a ghrelin-expressing vector into AGS cells and isolated a stable ghrelin-expressing cell line (AGS-GHRL8). AGS-GHRL8 cells secreted octanoylated ghrelin in accordance with the concentrations of octanoic acid in the culture medium. Given that ingested heptanoic acid is used for the acyl-modification of ghrelin, we evaluated whether heptanoic acid inhibits production of octanoylated ghrelin in AGS-GHRL8 cells. Butyric acid was used as a control. Indeed, heptanoic acid predictably decreased the secretion of octanoylated ghrelin, whereas butyric acid did not. The AGS-GHRL8 line established in this study will facilitate the screening of inhibitors of octanoylated ghrelin production.

Oleic Acid and Octanoic Acid Sensing Capacity in Rainbow Trout Oncorhynchus mykiss Is Direct in Hypothalamus and Brockmann Bodies

In a previous study, we provided evidence for the presence in hypothalamus and Brockmann bodies (BB) of rainbow trout Oncorhynchus mykiss of sensing systems responding to changes in levels of oleic acid (long-chain fatty acid, LCFA) or octanoic acid (medium-chain fatty acid, MCFA). Since those effects could be attributed to an indirect effect, in the present study, we evaluated in vitro if hypothalamus and BB respond to changes in FA in a way similar to that observed in vivo. In a first set of experiments, we evaluated in hypothalamus and BB exposed to increased oleic acic or octanoic acid concentrations changes in parameters related to FA metabolism, FA transport, nuclear receptors and transcription factors, reactive oxygen species (ROS) effectors, components of the KATP channel, and (in hypothalamus) neuropeptides related to food intake. In a second set of experiments, we evaluated in hypothalamus the response of those parameters to oleic acid or octanoic acid in the presence of inhibitors of fatty acid sensing components. The responses observed in vitro in hypothalamus are comparable to those previously observed in vivo and specific inhibitors counteracted in many cases the effects of FA. These results support the capacity of rainbow trout hypothalamus to directly sense changes in MCFA or LCFA levels. In BB increased concentrations of oleic acid or octanoic acid induced changes that in general were comparable to those observed in hypothalamus supporting direct FA sensing in this tissue. However, those changes were not coincident with those observed in vivo allowing us to suggest that the FA sensing capacity of BB previously characterized in vivo is influenced by other neuroendocrine systems.

Simultaneous Biosynthesis of Two Copolymers in Pseudomonas putida GPo1 Using a Two-Stage Continuous Culture System

The bacterial production of medium-chain-length polyhydroxyalkanoate (PHA) in continuous two-stage cultivation was investigated. Two chemostats were linked in sequence and Pseudomonas putida GPo1 was supplied with different concentrations of octanoic acid in the first and 10-undecenoic acid in the second reactor. PHA isolated from the second bioreactor was a blend of two copolymers typically consisting of poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHO) and poly(3-hydroxy-10-undecenoate-co-3-hydroxy-8-nonenoate-co-3-hydroxy-6-heptenoate) (PHUE) with structural (monomeric) purities of 85-95 mol %, indicating simultaneous PHA accumulation and degradation inside the cell. The maximum PHA content was found to be 53.8% of total cell dry weight, which is very high for mcl-PHA.

Optimization of octanoic acid and sulfur donor concentrations for lipoic acid production by Pseudomonas reptilivora

Using the optimal concentrations of octanoic acid (0.75 mM) and ethyl mercaptan (2 mM), as the most effective sulfur donor, Pseudomonas reptilivora produced 74 microg lipoic acid per dry cell weight at pH 7.5 and 30 degrees C in a fermenter over 9 h. The dry cell weight was 13.9 g l(-1).

Optical-Response Extraction of Au(III) with Bis(2,2'-dipyridyl-6-yl)diazene and Octanoic Acid

The optical-response extraction of Au(III) with an azo compound, bis(2,2′-dipyridyl-6-yl)diazene (BDPDA), was studied. The distribution ratio of Au was increased by the configuration change of BDPDA from trans to cis under UV irradiation (340 nm); however, the distribution ratios under UV irradiation were less than 3 times those under VIS irradiation (465 nm). For further improvement of optical-response extraction, the synergistic extraction of Au using octanoic acid as a synergist was tested. Octanoic acid was coordinated mainly with the complex of Au and cis-BDPDA, and effectively enhanced the hydrophobicity of the complex. The distribution ratio of Au under the UV irradiation increased with increasing the concentration of octanoic acid in the organic phase. In the presence of 3 mol/L octanoic acid, the distribution ratio under the UV irradiation reached up to 10 times that under the VIS irradiation.