Accumulation Of Organic Acids Research Articles

Assessment of organic acid accumulation and its related genes in peach

Fruit acidity is an important determinant of peach organoleptic quality, but its regulatory mechanism remains elusive. Measurement of organic acids in ripe fruits of seventy-five peach cultivars revealed the predominant components malate and citrate, accompanied by quinate. Organic acid accumulation increased at early stages of fruit growth, but exhibited a more dramatic reduction in low-acid cultivar during later stages of fruit development compared to high-acid cultivars. Low-acid cultivars showed citrate degradation and less transport of malate into the vacuole due to up- and down-regulation of a GABA pathway gene GAD and a malate transporter gene ALMT9, respectively. The NAD-MDH1 gene might control the rate-limiting step in malate synthesis, while three genes, PDK, PK, and ADH, could affect citrate synthesis through the pyruvate-to-acetyl-CoA-to-citrate pathway. Altogether, these results suggested that malate accumulation is controlled at the level of metabolism and vacuolar storage, while metabolism is crucial for citrate accumulation in peach.

Dynamics of microbial community and changes of metabolites during production of type Ι sourdough steamed bread made by retarded sponge-dough method.

Dynamics of microbial community and changes of metabolites during production of type Ι sourdough steamed bread made by retarded sponge-dough method (SSB) were studied. Lactobacillus sanfranciscensis and Lactobacillus pontis were the dominant bacterial species. Particularly, relative abundances of Lactobacillus sanfranciscensis were significantly higher than that of other sub-dominant bacterial species. The dominant fungal species were Saccharomyces cerevisiae and Kazachstania humilis, and the latter was the most predominant. A stable bacterial and fungal consortia was established in sponge dough retarded from 12 to 24h and main dough proofed from 30 to 60min. Metabolism preference for maltose of Lactobacillus sanfranciscensis favoured a mutualistic association with maltose-negative Kazachstania humilis, and hence contributing to their competitiveness and dominance. Volatile compounds became more abundant with much more esters as sponge retarding time extended. Probably, the accumulation of organic acids and ethanol contributed mostly to formation of ethyl esters in sponge dough during retarding.

Metabolism of Lactobacillus sakei Chr82 in the Presence of Different Amounts of Fermentable Sugars.

Lactobacillus sakei is widely used as a starter culture in fermented sausages since it is well adapted to meat environments and able to maintain high viability thanks to secondary pathways activated when hexoses are depleted (i.e., metabolism of pentoses and amino acids). In this study, a commercial strain of L. sakei was inoculated in a defined medium with ribose or glucose as the carbon source, at optimal or reduced concentrations, to evaluate its different physiological and metabolic responses in relation to different growth conditions. The results obtained with different approaches (HPLC, 1H-NMR, flow cytometry) evidenced different growth performances, amino acid consumptions and physiological states of cells in relation to the carbon source as an active response to harsh conditions. As expected, higher concentrations of sugars induced higher growth performances and the accumulation of organic acids. The low sugars amount induced the presence of dead cells, while injured cells increased with ribose. Arginine was the main amino acid depleted, especially in the presence of higher ribose, and resulted in the production of ornithine. Moreover, the 1H-NMR analysis evidenced a higher consumption of serine at the optimal sugars concentration (pyruvate production). This information can be helpful to optimize the use of these species in the industrial production of fermented sausages.

Differences in metabolites production using the Biolog FF Microplate™ system with an emphasis on some organic acids of Aspergillus niger wild type strains

This paper investigates the differences in some metabolites using Biolog FF Microplate™ system and the production of organic acids such as β-hydroxybutyric, p-hydroxyphenylacetic, and others. Another group of organic acids such as gluconic, oxalic and citric acid were studied during cultivation in a liquid medium. Four different Aspergillus niger (An) wild type strains were used as a model organism. Three strains, from the Banska Stiavnica – Sobov (An – S), Pezinok (An – P) and Slovinky (An – Sl) localities were isolated from contaminated old mining areas with soil with ultra acidic to strong alkaline reactions. The fourth strain isolated from the Gabcikovovo (An – G) locality was used for comparative purposes. According to the RAMP analysis, the strains are clustered into two groups, An – S and An – P (similarity 82%), An – G and An – Sl (similarity 64%) which correlates with the pH values of the original environment. However, significant differences were found in metabolic processes in the reaction with a wide range of organic acids. In general, the reactions with D-lactic acid and D-malic acid correlate with the results of the RAMP analysis of fungal genotype similarities, the An – S and An – P strains had an identical negative reaction, and an identical positive reaction was found in the An – Sl and An – G strains. During incubation the wild-type strains produced substantial amounts of gluconic acid, oxalic acid and small amounts of citric acid. The appearance and accumulation of organic acids was found to be highly pH dependent with the most active strain isolated from an ultra-acidic environment. The comparative strain differs entirely in the production of oxalic acid.

Metabolic and physiological adjustments of maize leaves in response to aluminum stress

Acidic soils with elevated aluminum (Al) saturations are worldwide distributed and harm the crop production in most of the tropical and subtropical regions. Under these conditions, root elongation may be impaired and thus disturbs water and nutrient uptake. Consequently, physiological responses of plants challenged with excess Al may resemble those of drought stresses. Here, we hypothesized that drought tolerant plants are also Al tolerant due to changes in growth, metabolic and physiological adjustments in leaves. Two maize genotypes, BRS1010 and BRS1055, sensitive and tolerant to drought, respectively, were hydroponically grown under controlled conditions and challenged with two Al concentrations (0 and 100 µM AlCl3) for 5 days. After treatment with Al, BRS1055 plants displayed increased leaf and stem elongation whereas the relative root growth rate remained unchanged. This was accompanied by unaltered root structure, photosynthetic efficiency and leaf primary metabolism. In sharp contrast, the BRS1010 plants were sensitive to Al, exhibiting a reduction in leaf and stem elongation and biomass accumulation in shoot and root, as well as greater structural damages in root tips. Additionally, in response to Al, lipid peroxidation increased in BRS1010 leaves in parallel to inhibition of photosynthetic performance and dark respiration. Moreover, compared to control treatment, the genotype BRS1010 displayed a large accumulation of sugars, amino acid, proteins and organic acids in leaves under Al stress. Therefore, the leaf physiology and metabolism are pivotal players in modulating Al tolerance in maize.

Phosphorus relieves aluminum toxicity in oil tea seedlings by regulating the metabolic profiling in the roots

Oil tea (Camellia oleifera Abel.) is an important edible oil tree mainly grown in acidic soils, whose growth and yield can be severely limited due to soil aluminum (Al) toxicity and phosphorus (P) deficiency. In this study, we investigated the physiological and metabolic responses of oil tea to Al and P treatment for an 8-week duration. Al reduced root length, root volume, and plant biomass, while P addition alleviated the effects of Al toxicity. P addition increased P content and reduced Al accumulation in roots. The profiles of 58 metabolites were significantly changed in roots of oil tea seedlings. Al toxicity increased various amino acids, but decreased many kinds of organic acids and carbohydrates. Interestingly, P addition reduced the amino acids accumulation which were induced by Al toxicity, while only a few organic acids changed under P supply. Most carbohydrates, including sucrose and glucose, significantly increased with P addition under Al toxicity. Results indicated that Al toxicity increased the accumulation of amino acids and reduced the accumulation of organic acids and carbohydrates, while the addition of P promoted root growth by alleviating the inhibition of protein synthesis and increasing carbohydrates content. However, P addition did not increase the organic acids content in roots.

Metabolome Profiling Supports the Key Role of the Spike in Wheat Yield Performance.

Although the relevance of spike bracts in stress acclimation and contribution to wheat yield was recently revealed, the metabolome of this organ and its response to water stress is still unknown. The metabolite profiles of flag leaves, glumes and lemmas were characterized under contrasting field water regimes in five durum wheat cultivars. Water conditions during growth were characterized through spectral vegetation indices, canopy temperature and isotope composition. Spike bracts exhibited better coordination of carbon and nitrogen metabolisms than the flag leaves in terms of photorespiration, nitrogen assimilation and respiration paths. This coordination facilitated an accumulation of organic and amino acids in spike bracts, especially under water stress. The metabolomic response to water stress also involved an accumulation of antioxidant and drought tolerance related sugars, particularly in the spikes. Furthermore, certain cell wall, respiratory and protective metabolites were associated with genotypic outperformance and yield stability. In addition, grain yield was strongly predicted by leaf and spike bracts metabolomes independently. This study supports the role of the spike as a key organ during wheat grain filling, particularly under stress conditions and provides relevant information to explore new ways to improve wheat productivity including potential biomarkers for yield prediction.

Achieve clean and efficient biomethane production by matching between digestate recirculation and straw-to-manure feeding ratios

Liquid digestate recirculation can fundamentally solve the problem of voluminous liquid digestate discharge for biogas projects. However, the uncertainty of the effect of recirculation under different feedstock restricts the application of recirculation technology. In this study, the comprehensive effects of straw to manure feeding ratios and liquid digestate recirculation on anaerobic digestion performance and microbial community structure were investigated. Recirculation was beneficial for biomethane production and digestion stability in digesters of corn stalk and straw/manure 3:1 by alleviating the loss of ammonia and alkalinity, while it aggravated the accumulation of ammonia and organic acids and reduced methane yield under 1:1, 1:3 and pig manure. The feeding ratios and recirculation formed a combined effect on ammonia concentration in the fermentation system, and when the total ammonia concentration was above 1500 mg/L, acids accumulation and decline in methane production would occur whether with recirculation or not. The microbial community structure varied corresponding to the fermentation state. In the well-run digesters, which were 3:1 with recirculation and 1:1 without recirculation, the dominant methanogens were Methanosaeta, while in the inhibited digesters, Methanosarcina and Methanosphaera dominated the methanogen community. Based on producing 1 GJ energy, the strategy of 3:1 with recirculation reduced the discharge of liquid digestate by 81.9% and the use of clean water by 65.4% compared to that of 1:1 without recirculation. An integrated approach of adjusting feedstock formula and selectively employing liquid digestate recirculation was proposed to produce liquid digestate on-demand with downstream application requirement, which will make biogas industry eco-friendly and cost-effective.

Characterization of Novel Intron Splice Mutations in Patients with Propionic Acidemia

Propionic Acidemia (PA) is a rare genetic metabolic disorder characterized by a deficiency in propionyl CoA carboxylase (PCC), an enzyme responsible for the proper breakdown of certain proteins and lipids. As a result, patients exhibit an abnormal accumulation of toxic organic acids, which can cause detrimental health problems. PA derives from mutations in PCCA and PCCB genes, which are responsible for expressing the vital subunits of PCC. Mutations in intronic sequences may cause errors in RNA processing, specifically with RNA splicing. If intronic segments are improperly included in the final mRNA form, the resultant products become nonfunctional. The goal of this project was to determine whether novel intron splice site mutations induce improper mRNA processing and, thus, nonfunctional proteins. To achieve this, we collaborated with genetics testing company Prevention Genetics to construct minigene plasmids containing intron mutations from patients. The minigene system was transfected into mouse fibroblast cells to allow mRNA processing to occur. RNA was isolated, reverse‐transcribed into cDNA, and sequenced to determine whether the mutated introns are splicing differently from the wildtype. Initial results indicate several identified intronic mutations contribute to an altered splicing pattern in patients with PA. Knowledge of the effect of these mutations on gene expression will strengthen the genetic database to help doctors diagnose PA in their patients, as well as help develop preventive and personalized treatments.Support or Funding InformationUWSP OSCAR Travel Grant (Up to $3,000 for three students)

Food waste composting - Is it really so simple as stated in scientific literature? – A case study

Food waste has recently gained much worldwide interest due to its influence on the environment, economy and society. Gathering and recycling of food waste is the essential issue in the waste management and the interest in processing food waste arises mainly out of influence of the processes of food putrefaction on the environment. Composting of food waste encounters a number of technical challenges, arising weak physical structure of food waste with weak porosity, high content of water, low carbon-to-nitrogen relation and fast hydrolysis and accumulation of organic acids during composting. Therefore, the aim of this study was to investigate the challenges facing installations intended for food waste composting, with the purpose to their optimization with use of appropriate additives. Physico-chemical, biochemical characteristics and phytotoxicity of the produced compost has been measured. Two additives (20% biochar and 20% sawdust) were chosen from experimental variants I-XII containing different additives (biochar, Devonian sand, sawdust) in diverse concentration. The use of selected additives seems to slightly increase potential of hydrogen value and carbon-to-nitrogen ratio, while decreasing electrical conductivity in comparison with control sample. The results obtained also show that the addition of biochar leads to an increase dehydrogenase, phosphatase and arylsulphatase activities and addition of sawdust has a positive effect on beta-D-glucosidase, protease, phosphatase and arylsulphatase activities. The phytotoxicity test shows that the compost made of food waste (control sample) and with addition of biochar is toxic to plants. By contrast, the addition of sawdust shows that the compost was not phytotoxic. In conclusion, the addition of additives does not provide unambiguous results in terms of the quality of the final product in all monitored parameters. Therefore, we can state that food waste was reduced and hygienized, and that the final product does not meet conditions for mature compost.

Efficient production of surfactin from xylose-rich corncob hydrolysate using genetically modified Bacillus subtilis 168.

As one of the most powerful biosurfactants, surfactin has extensive application prospects in numerous industrial fields. Bacillus subtilis 168 was genetically modified to produce surfactin by increasing the supply of the precursor fatty acyl-CoA by overexpressing 4' phosphopantetheinyl transferase, medium-chain acyl-acyl carrier protein (ACP) thioesterase and fatty acyl CoA ligase (encoded by sfp, bte, and yhfL, respectively), and knocking out acyl-CoA dehydrogenase (encoded by fadE). The resulting recombinant strain BSFX022 produced 2203mg/L surfactin with xylose as carbon source. The lower accumulation of organic acids with xylose as carbon source made it possible to maintain surfactin production in a non-buffered fermentation system, and the yield reached 2074mg/L. Furthermore, to reduce the costs, waste biomass such as corncob hydrolysate and monosodium glutamate wastewater (MGW) were used, and 2032mg/L of surfactin was produced in the optimal waste-based medium. To our best knowledge, this is the first report of surfactin production using genetically modified Bacillus subtilis 168 with xylose as carbon source.

Light-responsive expression atlas reveals the effects of light quality and intensity in Kalanchoë fedtschenkoi, a plant with crassulacean acid metabolism.

BackgroundCrassulacean acid metabolism (CAM), a specialized mode of photosynthesis, enables plant adaptation to water-limited environments and improves photosynthetic efficiency via an inorganic carbon-concentrating mechanism. Kalanchoë fedtschenkoi is an obligate CAM model featuring a relatively small genome and easy stable transformation. However, the molecular responses to light quality and intensity in CAM plants remain understudied.ResultsHere we present a genome-wide expression atlas of K. fedtschenkoi plants grown under 12 h/12 h photoperiod with different light quality (blue, red, far-red, white light) and intensity (0, 150, 440, and 1,000 μmol m–2 s–1) based on RNA sequencing performed for mature leaf samples collected at dawn (2 h before the light period) and dusk (2 h before the dark period). An eFP web browser was created for easy access of the gene expression data. Based on the expression atlas, we constructed a light-responsive co-expression network to reveal the potential regulatory relationships in K. fedtschenkoi. Measurements of leaf titratable acidity, soluble sugar, and starch turnover provided metabolic indicators of the magnitude of CAM under the different light treatments and were used to provide biological context for the expression dataset. Furthermore, CAM-related subnetworks were highlighted to showcase genes relevant to CAM pathway, circadian clock, and stomatal movement. In comparison with white light, monochrome blue/red/far-red light treatments repressed the expression of several CAM-related genes at dusk, along with a major reduction in acid accumulation. Increasing light intensity from an intermediate level (440 μmol m−2 s−1) of white light to a high light treatment (1,000 μmol m–2 s–1) increased expression of several genes involved in dark CO2 fixation and malate transport at dawn, along with an increase in organic acid accumulation.ConclusionsThis study provides a useful genomics resource for investigating the molecular mechanism underlying the light regulation of physiology and metabolism in CAM plants. Our results support the hypothesis that both light intensity and light quality can modulate the CAM pathway through regulation of CAM-related genes in K. fedtschenkoi.

Evaluation of the comparative morphological and quality in fig (Sichuan, China) with different colors under different ripening stages

Fig (Ficus carica L.) has been used in China as food and medicine for millennia, and globally has been consumed increasingly as a healthy food. Sichuan, especially the Weiyuan area, always had the reputation of producing best fig quality. The comparative morphological and quality of 6 fig cultivars were correlated with the main planting fig with three different colors in Sichuan, China: Yellow (Orphan, Browns Wick), Red (Bpjihon, Masui Dauphine, Wild-type), Purple (Japanese Purple Fruit). This study aimed to explore the morphological characteristics in fig, and composition, content and dynamic changes rule of the organic acids and anthocyanins in different parts (peel and pulp) of fruits under different ripening stages (eight mature and full mature). These provide important theoretical bases for the improvement, production, and quality assessment of fig cultivars. In this experiment, high performance liquid chromatography (HPLC) for the determination of organic acids and anthocyanins in figs was established for the first time. Each organic acid and anthocyanin component had a linear coefficient of >0.996, and good values were obtained for linear correlation, precision, and reproducibility. During the ripening of fig, malic acid, quinic acid, and citric acid were the main organic acids of fig, followed by tartaric acid and succinic acid, with the lowest content found for fumaric acid. The highest anthocyanin content was observed for cyanidin-3-O-glucoside, followed by cyanidin-3-O-rutinoside, and cyanidin-3,5-diglucoside had the least content. The accumulation pattern of organic acids and anthocyanins was observed to change. The organic acids accumulation pattern changed from malic acid and quinic acid to malic acid, citric acid accumulation or malic acid, citric acid and quinic acid to the accumulation of the three organic acids. The accumulation pattern of anthocyanins was mainly composed of cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside accumulation, and the change during ripening was not significant. This pattern may play an important role in the determination of acidity, sweetness, and flavor quality of fig fruits in Sichuan, China.

Expression pattern of sugars and organic acids regulatory genes during watermelon fruit development

Watermelon has a fleshy fruit and that is the reason sugars and organic acids play a key role in taste formulation. So far, there is no comprehensive study in watermelon regarding accumulation and regulation of sugars and organic acids. To understand the behaviour of sugars and organic acids two watermelon inbred lines “203Z” (high sugar, low acid) and “SW” (low sugar, high acid) were used. The contents of each sugars and organic acids at three different developmental stages were measured via ion chromatography. Total 38 genes which were involved in sugars and organic acids metabolism and transport were screened out in watermelon fruit flesh. Genes for sugars and organic acids regulation and transport were highly expressed during watermelon fruit ripening. Fructose was observed as the main sugar and malic acid was the main organic acid in watermelon fruit flesh. WMFBPA-2 that is involved in fructose breakdown was positively and significantly correlated with fructose. Aluminum activated malate transporters and malate dehydrogenase genes were involved in malate regulation and degradation. It was concluded that WMALMT-3 may participate in the regulation of malic acid and its accumulation in vacuole during watermelon fruit development. WMCS was found to be associated with citric acid regulation. This study will improve our understanding and lay foundation to explore the function of these genes and improvement of watermelon fruit quality.

Production of γ-Aminobutyric Acid and Its Supplementary Role in the TCA Cycle in Rice (Oryza sativa L.) Seedlings

Germination of rice (Oryza sativa L.) results in rapid accumulation of γ-aminobutyric acid (GABA), but its precise role in the process remains unclear. In this study, we analyzed GABA shunt-related amino acids [glutamate (Glu), alanine (Ala), and GABA] and tricarboxylic acid (TCA)-cycle-related organic acids (pyruvate, citrate, α-ketoglutarate, succinate, fumarate, and malate) in rice, under dark and anaerobic conditions, to investigate the role of GABA in rice germination. The change in the GABA content before and after germination was compared using 2 cultivars selected from 18 varieties of Korean rice. Correlation analysis indicated that the metabolism of GABA in germinating rice might be related to Ala metabolism. In a two-way stress study, GABA content was found to be positively related to TCA-cycle organic acid contents (α-ketoglutarate, succinate, fumarate, and malate) but show a negative relation with GABA shunt-related amino acid contents (Glu, Ala). In the dark, accumulation of TCA-cycle organic acids was observed, but Glu and Ala levels were reduced. GABA treatment (1 mM) in dark conditions produced TCA-cycle organic acids at levels similar to those in light conditions. In anaerobic conditions, TCA-cycle-related compounds accumulated at a high level, but Glu and Ala were remarkably reduced compared with normal conditions. As a result, GABA shunt is connected with TCA-cycle organic acids, but not amino acids. In conclusion, the present research suggests that GABA, accumulated in certain stress conditions, supplies organic acids such as succinate to the TCA cycle.

The Role of Selected Lactic Acid Bacteria on Organic Acid Accumulation during Wet and Spray-Dried Fish-based Silages. Contributions to the Winning Combination of Microbial Food Safety and Environmental Sustainability.

Organic acid contents of acidified and fermented fish silages made from gibel carp (Caracius gibelio) and klunzinger’s ponyfish (Equulites klunzingeri) fishes, and from fish processing residues or by-products, were determined and studied. The silages were undertaken in wet and spray-dried fish-based raw-materials for 3 weeks at room temperature (ca. 25 °C). Selected lactic acid bacteria (LAB) of Enterococcus gallinarum, Lactobacillus brevis, Lactobacillus plantarum, Pediococcus acidilactici, and Streptococcus spp. were employed to produce fermented fish-based silages, while acidified silage was prepared resorting to the addition of formic acid (3%, v/v). Lactic and propionic acids were the dominant produced organic acids, while succinic acid was formed at the smallest amounts in fermented silages. In the acidified silage, lactic and formic acids were produced in amounts higher than 800 and 1000 mg organic acid/100 g sample, respectively. Among the fermented fish-based silages, LAB strains unfolded considerable ability to presumptively produce propionic acid in gibel carp silage (>2370 mg organic acid/100 g sample). Spray-dried fermented silages displayed significantly higher organic acid content than wet silages. Propionic acid accumulation was found at the highest levels in gibel carp silage fermented with L. plantarum (6335.40 mg propionic acid/100 g sample). This research effort pointed out the good capability of various selected lactic acid bacteria strains to produce significant amounts of organic acids—especially lactic, acetic, and propionic acids—during the fermentation of fish-based silages. In terms of food safety and quality, such a production of relatively high amounts of organic acids in wet and spray-dried fish-based silages clearly indicated their suitableness to be used for animal feed.

Nitrate amendment to control sulphide accumulation in shrimp ponds

The production of shrimp is often performed in earthen outdoor ponds in which the input of feed and faeces on the bottom results in deterioration of the water quality that results in a negative impact on the aquatic animals and the environment.Nitrate application in shrimp ponds could improve pond water and sediment quality by oxidizing anaerobic zones of the sediment. This study was conducted to evaluate the possible benefits of nitrate treatment in combination with probiotics application to decrease sulphide formation in shrimp ponds, which is a crucial problem during the growth phase of shrimp. Three sets of experiments were conducted to describe the mechanism of nitrate treatment: a dual dose nitrate treatment at the start and after 14 days that investigated nitrate treatment with concentrations of 50, 100 and 200 mg/L NO3−, a multiple dose nitrate treatment where lower doses of nitrate (12.5, 25 and 50 mg/L NO3−) were tested with more frequent application (every 4 days) and a microbially assisted nitrate treatment in which 50 mg/L NO3− treatment was applied every 4 days with and without presence of a single probiotic application. A batch system including shrimp feed and faeces, representing the bottom waste produced during 90 days of shrimp culture, was used to test the effect of nitrate addition under anaerobic conditions that mimic the dead zones in shrimp pond bottoms where high amounts of organic matter accumulate. Nitrate addition acted as a curative solution for hydrogen sulphide (H2S) accumulation, rather than preventive. Nitrate amended treatments (12.5 mg/L.day NO3) decreased the accumulated H2S in the headspace of incubation bottles by 93 ± 3% compared to the controls. Nitrate addition increased pH and decreased organic acids accumulation to trace amounts. To justify the decrease in H2S concentration apart from the effect sulphur speciation through pH increase, a separate test was conducted to compare the effect of NaOH with nitrate treatment, in which nitrate treatment resulted in a 62.8% higher decrease in H2S concentrations than the NaOH treatment. The use of a denitrifying strain did not improve the beneficial effect of nitrate, indicating that intrinsic capacity for anoxic conversion of waste by the present community was sufficient. In conclusion, nitrate treatment showed a potential to control H2S accumulation in the shrimp ponds that is a critical problem during the growth of shrimp.

Effect of commercial starter cultures on the quality characteristics of fermented fish-chili paste

The effects of commercial starter cultures on the quality characteristics of fermented fish-chili paste were investigated. Five batches of fish-chili paste were prepared with different starter cultures, namely, SBM-52 (Staphylococcus xylosus, Staphylococcus carnosus, Pediococcus pentosaceus and Pediococcus lactis), PRO-MIX5 (Staphylococcus xylosus, Lactobacillus plantarum and Lactobacillus sakei), WBX-43 (Staphylococcus xylosus and Staphylococcus carnosus), V3 (Lactobacillus plantarum), and CO (spontaneous fermentation) as the control. The results showed that all the starter cultures accelerated the growth of lactic acid bacteria and obviously reduced the Enterobacteriaceae count compared with the CO batch. SBM-52, PRO-MIX5 and V3 quickly reduced the pH, and there was no obvious difference in the protease activities among these five batches (P > 0.05). The SBM-52 batch displayed a significantly higher level of total free amino acids than the control (P < 0.05). The accumulation of organic acids was mainly due to lactic acid in all the samples. Volatile analysis indicated that more ester compounds were detected in WBX-43 compared with the other samples. E-nose analysis showed an obvious difference in the overall odor among the different samples. In conclusion, the starter cultures of WBX-43 and SBM-52 could be used for the production of high-quality fish-chili paste with better flavor.

Utilization of Rumen Content by Indigenous Microorganisms in a Modified Anaerobic Digester

The current work was designed to assess the effect of modification of model digester on the kinetics that affects efficiency in biogas generation using bovine rumen content as the feedstock. A biogas plant consisting of conventional and modified fixed-dome digesters (each with 2 m3 capacity) was established; and bovine rumen content was used as feedstock. Standard methods were used to determine the kinetic (physicochemical and microbiological) parameters. Identification of fungal and bacterial species involved in the process was carried out by genomic study of the 18S rRNA and 16S rRNA regions, respectively; amplified using universal forward and backward primers for fungi (NS1/NS4), bacteria ((515F/926R) and archaea (Met86F/Met140R); submitted to GenBank and analysed using Blast Programme at National Centre for Biotechnology Information website. A mass balance approach was used to estimate the theoretical gas yield from the total solid/volatile sold lost. It was found that the temperature in both modified and conventional digesters was uniform throughout the hydraulic retention time, between 32 to 34.5°C, indicating a mesophilic range. The pH level was found to be lower in the modified digester compared to the conventional digester, indicating higher accumulation of organic acids. The mean total solid was found to drop from 12.49±0.53 to 3.82±0.21 in the modified digester after digestion, while this was from 13.30±0.4 to 6.69±0.16 in the conventional digester. The mean volatile solid drops from 66.67±1.62 to 36.13±0.27 in the modified digester after digestion, while it was from 69.94±1.54 to 54.23±1.33 in the conventional digester. The theoretical biogas yield was higher in the modified digester (87 mg/l) compared to the conventional one (65 mg/l). The microbial counts were observed to be affected by the kinetic parameters in both the digesters. The organisms identified were: Lactobacillus acidophilus, Bacteroides nordii, Clostridium perfringens, Clostridium acetobutylicum, Proteus vulgaris, Methanosarcina sicilia, Methanosarcina mazei, Methanobrevibacter ruminantium, Fusarium solani, Fusarium graminearum, Aspergillus niger and Penicillium specie. Conclusively, the modified digester, under a manual stirring at 10 round/min, 3 times a day at an interval of six hours, has appreciably generated higher theoretical biogas yield after 8 weeks hydraulic retention time. The agitation of the slurry using the improvised stirrer in the modified digester has significantly facilitated the utilization of the bovine rumen content by the indigenous microorganisms. Modification of digester to enhance mixing of the feedstock should therefore be encouraged in household anaerobic digesters.

Influence of varietal characteristics the cabbage in the quality of the products used for pickling after a long storage period

Relevance. Fermentation of cabbage is a common way of processing, which allows to preserve and strengthen its useful qualities. To date, breeders have proposed a significant number of varieties and hybrids of cabbage, each of which has its own individual biochemical characteristics. Traditional sauerkraut is carried out after harvest. Long storage can affect the change in the content of organic acids and sugars in cabbage.Methods. The aim of the work was to study the parameters of the fermentation process of eight varieties and hybrids of cabbage by selection in the Federal State Budgetary Scientific Institution Federal Scientific Vegetable Center by the intensity of sugar reduction, accumulation of organic acids, organoleptic parameters and activity of lactic acid microorganisms. Fermentation was carried out after a 5-month period of storage of heads.Results. The results showed that the storage period did not affect the fermentation result of most of the studied varieties and hybrids of cabbage. There are varietal differences in the initial content of mono-and disaccharides, organic acids, which affected the fermentation process. The increased content of malic acid in the variety population Podarok, F1 Severyanka contributed to the slowdown of the first stage of fermentation. Varietal features of the Parus population contributed to the slowdown of the first and second stages of fermentation, which was manifested in a decrease in the rate of destruction of sugars. Variety Zymovka 1474 in the process of processing by fermentation accumulates a significant amount of succinic acid, which can characterize its special difference among the studied varieties and hybrids. The best organoleptic characteristics were distinguished by hybrids of fermented cabbage F1 Likova, F1 Natali, F1 Mechta and F1 Snezhinka. The results of the study suggest that the processing of cabbage by fermentation should take into account its individual varietal biochemical features. This will not only preserve the valuable nutritional properties of the cabbage itself, but also strengthen them by optimizing the natural process of lactic acid fermentation. The result will be the best organoleptic effect achieved by an optimal combination of lactic and citric acids and mono-sugars.