Alkali-soluble Fractions Research Articles

In Vitro Studies of Pumpkin (Cucurbita moschata var. Kashi Harit) Seed Protein Fraction(s) to Evaluate Anticancer and Antidiabetic Properties.

Chronic diseases like cancer and diabetes are the major public health concerns of India and worldwide. Nowadays, plant-derived products are in great demand for the treatment of these diseases. Pumpkin seeds are traditionally implicated for their pharmacological properties, as exemplified by benign prostatic hyperplasia. Earlier, pumpkin seed proteins were extracted by the Osborne method, and their functional and nutritional qualities were evaluated. Here, the aim is to assess in vitro, the anticancer and antidiabetic properties of seed protein fractions. HepG2, MDA-MB-231, and MCF-7 cell lines were treated with water-soluble (WF) and alkali-soluble fractions (AF) to assess cytotoxicity, while pancreatic β-cells and insulin resistance (IR) - HepG2 cell lines were treated with WF to evaluate the antidiabetic potential. WF and AF showed cytotoxic effects towards HepG2 and MDA-MB-231 cell lines, suggesting apoptosis-mediated anticancerous activity. WF potentiates glucose-stimulated insulin secretion in pancreatic β-cells, in a dose-dependent manner. In IR-HepG2 cell line studies, control, metformin, and WF-treated groups showed uptake of glucose, when compared to the diabetic group, which is well-correlated with the upregulated expressions of GLUT2 and GLUT4 transporters in these groups. These results indicate that proteins from WF and AF may have anticancerous and antidiabetic properties and thus have the potential to utilize pumpkin proteins in the management of cancer and diabetes.

Общее содержание и фракционный состав белка в семенах сортов сои селекции ФГБНУ ФНЦ ВНИИМК

The use of high-protein soybean cultivars is one of the most important reserves for solving the problem of protein deficiency in the production of feed and food products. In recent years, soybean cultivars with high productivity potential and improved biochemical composition of seeds have been developed in the V.S. Pustovoit All-Russian Research Institute of Oil Crops. The cultivars approved for usage in various regions of the Russian Federation were assessed by the total protein content in seeds and its fractional composition as the main biochemical characteristics of raw materials. The cultivars with a high content of water-soluble (albumin) and stable indicators of salt- and alkali-soluble (globulins and glutelins) fractions, respectively, were noted. It was established that the studied indicators depended not only on the genetic properties of the cultivars, but also on the characteristics of the conditions of the reproduction year. Thus, in soybean seeds of the 2021 harvest, the cultivars Iney (39.0%), Triada (39.9%) and Graya (42.0%) stood out with the highest protein content; in terms of albumin content in protein – Graya and Bars (91.8 and 92.0%, respectively). And in the seeds of the 2022 harvest, the maximum protein content was observed in the cultivars Puma (38.9%), Graya (39.4%) and Gnom (40.2%), albumin content – Barguzin (92.7%), Bars (94.5%) and Puma (95.1%). A weakly positive correlation was noted between the total protein content and the proportion of the water-soluble fraction in it (r = +0.33).

Vicilin and legumin storage proteins are abundant in water and alkali soluble protein fractions of glandless cottonseed

In this work, we sequentially extracted water (CSPw)- and alkali (CSPa)-soluble protein fractions from glandless cottonseed. SDS-Gel electrophoresis separated CSPw and CSPa to 8 and 14 dominant polypeptide bands (110–10 kDa), respectively. Liquid chromatography-electrospray ionization-tandem mass spectrometry identified peptide fragments from 336 proteins. While the majority of peptides were identified as belonging to vicilin and legumin storage proteins, peptides from other functional and uncharacterized proteins were also detected. Based on the types (unique peptide count) and relative abundance (normalized total ion current) of the polypeptides detected by mass spectrometry, we found lower levels (abundance) and types of legumin isoforms, but higher levels and more fragments of vicilin-like antimicrobial peptides in glandless samples, compared to glanded samples. Differences in peptide fragment patterns of 2S albumin and oleosin were also observed between glandless and glanded protein samples. These differences might be due to the higher extraction recovery of proteins from glandless cottonseed as proteins from glanded cottonseed tend to be associated with gossypol, reducing extraction efficiency. This work enriches the fundamental knowledge of glandless cottonseed protein composition. For practical considerations, this peptide information will be helpful to allow better understanding of the functional and physicochemical properties of glandless cottonseed protein, and improving the potential for food or feed applications.

Effect of integrated treatment on enhancing the enzymatic hydrolysis of cocksfoot grass and the structural characteristics of co-produced hemicelluloses

BackgroundCocksfoot grass (Dactylis glomerata L.) with high biomass yield and rich cellulose can be used to produce bioethanol as fuel additive. In view of this, ultrasonic and hydrothermal pretreatments followed by successive alkali extractions were assembled into an integrated biorefinery process applied on cocksfoot grass to improve its enzymatic hydrolysis. In this work, the effects of ultrasonic and hydrothermal pretreatments followed by sequential alkali extractions on the enzymatic hydrolysis of cocksfoot grass were investigated. In addition, since large amount of hemicelluloses were released during the hydrothermal pretreatment and alkali extraction process, the yields, structural characteristics and differentials of water- and alkali-soluble hemicellulosic fractions isolated from different treatments were also comparatively explored.ResultsThe integrated treatment significantly removed amorphous hemicelluloses and lignin, resulting in increased crystallinity of the treated residues. A maximum saccharification rate of 95.1% was obtained from the cellulose-rich substrate after the integrated treatment. In addition, the considerable hemicelluloses (31.4% water-soluble hemicelluloses and 53.4% alkali-soluble hemicelluloses) were isolated during the integrated treatment. The released water-soluble hemicellulosic fractions were found to be more branched as compared with the alkali-soluble hemicellulosic fractions and all hemicellulosic fractions were mixed polysaccharides mainly composed of branched xylans and β-glucans.ConclusionThe combination of ultrasonic and hydrothermal pretreatments followed by successive alkali extractions can dramatically increase the enzymatic saccharification rate of the substrates and produce considerable amounts of hemicelluloses. Detailed information about the enzymatic hydrolysis rates of the treated substrates and the structural characteristics of the co-produced hemicelluloses will help the synergistic utilization of cellulose and hemicellulose in cocksfoot grass.

Cell Wall Polysaccharide Composition of Grafted 'Liberty' Watermelon With Reduced Incidence of Hollow Heart Defect.

Grafting watermelon scions to interspecific squash hybrids has been found to increase fruit firmness. Triploid (seedless) watermelon are prone to hollow heart (HH), an internal fruit disorder characterized by a crack in the placental tissue expanding to a cavity. Although watermelon with lower tissue firmness tend to have a higher HH incidence, associated differences in cell wall polysaccharide composition are unknown. Grafting “Liberty” watermelon to “Carnivor” (interspecific hybrid rootstock, C. moschata × C. maxima) reduced HH 39% and increased tissue firmness by 3 N. Fruit with and without severe HH from both grafted and non-grafted plants were analyzed to determine differences in cell wall polysaccharides associated with grafting and HH. Alcohol insoluble residues (AIR) were sequentially extracted from placental tissue to yield water soluble (WSF), carbonate soluble (CSF), alkali soluble (ASF), or unextractable (UNX) pectic fractions. The CSF was lower in fruit with HH (24.5%) compared to those without HH (27.1%). AIRs were also reduced, hydrolyzed, and acetylated for GC-MS analysis of monosaccharide composition, and a portion of each AIR was methylated prior to hydrolysis and acetylation to produce partially methylated alditol acetates for polysaccharide linkage assembly. No differences in degree of methylation or galacturonic and glucuronic acid concentrations were found. Glucose and galactose were in highest abundance at 75.9 and 82.4 μg⋅mg–1 AIR, respectively, followed by xylose and arabinose (29.3 and 22.0 μg⋅mg–1). Mannose was higher in fruit with HH (p < 0.05) and xylose was highest in fruit from grafted plants (p < 0.05). Mannose is primarily found in heteromannan and rhamnogalacturonan I side chains, while xylose is found in xylogalacturonan or heteroxylan. In watermelon, 34 carbohydrate linkages were identified with galactose, glucose, and arabinose linkages in highest abundance. This represents the most comprehensive polysaccharide linkage analysis to date for watermelon, including the identification of several new linkages. However, total pectin and cell wall composition data could not explain the increased tissue firmness observed in fruit from grafted plants. Nonetheless, grafting onto the interspecific hybrid rootstock decreased the incidence of HH and can be a useful method for growers using HH susceptible cultivars.

Influence of IR radiation on the biological value of flax seeds

Relevance. The growing demand for flax seeds as a biologically active food component is explained by the rising interest to the healthy lifestyle. In this regard, the requirements for food safety of biologically active raw materials are increasing. Heat treatment of plant materials is an effective method for the eliminating of factors that reduce nutritional and biological value food components. Thermal treatment of flax seeds with infra-red irradiation (IR) is a promising direction for the stabilizing of seeds component composition. Short-term high-temperature treatment of raw materials under the influence of IR (micronization) increases the microbiological purity of raw materials. However, there is not enough information about how the biological value parameters changing. The aim of this study was to study the effect of the micronization process on the biological value of flax seeds.Results. Total protein content of tested flax seeds did not changed after applying of IR treatment. The increase in the content of crude oil in micronized flax seeds is explained by the conversion of phospholipids into extractable lipids. A comparative analysis of the protein complex of flax seeds before and after micronization showed a change in the ratio of protein fractions: the content of the water-soluble fraction (albumin) decreased in four-times, the content of glutens, an alkali-soluble fraction, increased significantly, the content of globulins slightly increased. Around 20% of proteins passed into an insoluble residue. The adequacy of the final results of the low temperature cold-pressing and the short-term high-temperature treatment with IR radiation in the ratio of protein fractions in flax seeds was shown. Changes in the ratio of protein fractions occurring during these technological operations are similar. It was concluded that under the influence of shortterm high-temperature IR-treatment the soft denaturation of the proteins is occurred. That effect of micronization on flax seed increases the protein digestibility

Comparison of the wood bonding performance of water- and alkali-soluble cottonseed protein fractions

The interests in biobased wood adhesives have been steadily increasing in recent years. Cottonseed protein isolate has shown potential as a renewable biobased adhesives. For a better understanding of the adhesive performance and mechanisms of cottonseed protein, we sequentially separated the isolated material into water-soluble (CSPw) and alkali-soluble (CSPa) fractions. The adhesive properties of both fractions on bonding maple wood veneers were tested at their natural pH (4.0 for CSPw and 7.0 for CSPa) and a common pH 11.0. The dry, wet, and soaked (i.e. wet and then re-dried) strength at break of the wood pairs bonded by CSPa were always higher than the values found for CSPw under the same conditions. Per the solubility and rheological analysis, the observed differences in bonding performance could be attributed to the fact that CSPw is more hydrophilic and lower in pI. ATR FTIR analysis was directly applied to the adhesive-coated surface area of maple strips cohesively broken by shear tests. Qualitative FTIR spectral features and quantitative contact angle measurement of the adhesive-coated maple surface evidenced the better wettability of cured CSPa than CSPw adhesives. Lesscarbohydrates leached out of CSPa during water soaking relative to CSPw. These observations increased the mechanistic knowledge of seed protein products functioning as wood adhesives, and would be helpful for the design and tuning of their future functional performance in green applications.

Distribution of radiocarbon in sediments of the cooling pond of RBMK type Ignalina Nuclear Power Plant in Lithuania.

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for”Channelized Large Power Reactor”). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947–2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947–1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4–13.6 pMC during the first 15 years of plant operation. However, during the 2000–2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000–2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.

Humic Acid Transformation by the Fungus Cerrena unicolor Growing on Cellulose and Glucose

Microbial degradation of lignocellulose and soil organic matter is an important process controlling CO2 flow into the atmosphere, which is mostly carried out by fungi. The alkali-soluble fraction, which is represented mostly by the so-called humic acids (HA), dark-colored compounds of phenolic nature, constitute ~30‒70% of soil Corg. This is the first report on efficient degradation of soil HA under cellulolytic conditions; cellobiose dehydrogenase (CDH), an oxidative enzyme of the cellulolytic complex, was shown to play the key role in this process. Growth of a wood-decomposing fungus Cerrena unicolor on cellulose (CDH and laccase production) and glucose (laccase production) resulted in HA decolorization by 60 and 20%, respectively. HA depolymerization in the presence of CDH and its polymerization in the presence of laccase were shown by gel filtration experiments with the culture liquid and pure enzyme preparations. HA degradation in the presence of CDH was inhibited by radical scavengers, indicating the radical nature of this process (probably the Fenton’s reaction). HA depolymerization by CDH decreased in the presence of laccase, while HA polymerization by laccase decreased in the presence of CDH. Thus, the interaction of these enzymes affects HA transformation under cellulolytic conditions. These results improve our understanding of the mechanisms of microbial degradation of the aromatic components of soil humus and of the ecological functions of wood-decomposing fungi grown under cellulolytic conditions.

Resolving the nanostructure of sodium carbonate extracted pectins (DASP) from apple cell walls with atomic force microscopy and molecular dynamics

The diluted alkali-soluble fraction of the cell wall pectic matrix extracted with sodium carbonate (DASP) from apple fruit (M. domestica cv. Golden Delicious) was subjected to extensive analysis aimed at refining the current view concerning its molecular structure. Pectins were examined by means of atomic force microscopy (AFM) and HPLC chemical analysis. In addition to this, computational chemistry was employed to characterize the structural features of the basic plant cell wall polysaccharides and their possible assemblies. The AFM imaging revealed that DASP molecules deposited on mica structurally resembled rod-like objects, consisting of relatively long linear sections separated by bend points or branches. Locally molecules also formed aggregates, which were visible as an amorphous phase, concentrated around linear sections. Based on chemical analysis combined with molecular dynamics (MD) the linear chains were identified as sections of unbranched homogalacturonan, while the second most abundant polysaccharide present in DASP – arabinose – was considered to constitute the amorphous aggregates. The study showed that despite being present in small amounts, rhamnose is an important factor affecting the formation of the characteristic shape of DASP molecules on mica. The structural characterization of the bend points showed that linear molecules oriented at specific angles are most likely to be formed by two sections of homogalacturonan separated by a single rhamnose unit. AFM images confirmed that this is a common feature of the molecular structure of the DASP fraction, suggesting a possible role in the networking of pectic polysaccharides. Rhamnose interspersions within the homogalacturonan chains lead to the formation of spatial structures, which resemble kinked rods with segments having the ability to change their relative positions. The higher mobility of the linear sections as well as the higher number of segments increases the number of possible interactions with surrounding molecules and thus increases its ability to form gels. Therefore, it is expected that the number of rhamnose units and the length of the linear homogalacturonan sections will be one of the factors that influence the gelling abilities of pectin. Furthermore, it was proposed that branch points are created, similar to bend points, by single interspersions of rhamnose, which connect three homogalacturonan chains or short sections (two or three dimers) of rhamnogalacturonan-I with a homogalacturonan side branch. The third proposed alternative was a complex of two adjacent homogalacturonan chains, one of them having a single rhamnose insertion causing a bend in the structure.

Experience of biotechnology method applications in meat processing industry

Nowadays one of the main regulatory documents governing the future of food production in Russia is the “Food Security Doctrine of the Russian Federation” formulated in order to implement the state economic policy in the field of ensuring food security of the Russian Federation, aimed at reliable provision of the country’s population with food products, the development of domestic agricultural and fishery complexes. In the past 40 years, the use of nano- and biotechnologies in the processing of animal and fish raw materials has been widely developed. A large number of scientific studies are aimed at biotechnology method applications in the production of meat products, in particular the use of enzyme proteolytic preparations. The aim of the research presented in this article was to study the dynamics of the hydrolysis of water-, saltand alkali-soluble fractions of low-grade beef and lamb proteins with Megaterin, an enzyme preparation of animal origin. The fulfilled studies allow more precise approach to the use of enzyme preparations for the processing of basic raw materials by the meat industry.

The optical properties in alkali-soluble fractions extracted from newly shed litters in a subalpine forest

Humification of plant detritus is an important pathway for soil organic matter formation. The long-standing studies considered that humification proceeds at very late stages of litter decomposition, while the degree of humification in newly shed litters before decomposition remains unclear. In this study, we aimed to explore the degree of humification and conjugate structures of humic substances in newly shed litters, and their variations between litter types with different chemical components and between seasons with different environmental conditions. In this study, we collected fresh foliar (evergreen vs. deciduous and tree vs. shrub), twig, flower, and fruit litters by litter traps in a subalpine forest on the eastern Tibetan Plateau monthly from April to November 2016. The humification degrees of these newly shed litters were evaluated by the optical properties (i.e., ΔlogK, E4/E6, and A600/C) of the alkaline-extracted humic acid-like solutions. E4/E6 and ΔlogK are often used to evaluate the degree of humification, and these values were also used to classify the maturity levels of humic substances. We found that the ΔlogK, E4/E6, and A600/C values varied greatly among seasons with a higher degree of humification observed in August than in the other months for foliar litter. Compared with other litter components, foliar litter exhibited higher ΔlogK, E4/E6, and A600/C values, indicating that fresh foliar litter had a lower degree of humification than the other litters. Twig litter had more stable and abundant precursors of soil organic matter with a higher degree of humification. Moreover, higher degrees of humification with lower ΔlogK and E4/E6 values were observed in evergreen and tree litter species than in deciduous and shrub species, indicating that deciduous and shrub species retained strong abilities to sequester carbon (C). The degree of humification in newly shed litters was strongly affected by chemical components. Twig litter had more stable and abundant precursors of soil organic matter with high degree of humification. Deciduous species and shrub species retained strong abilities to sequester C in cold biomes. Additionally, the humic substances in newly shed litters were very young (type Rp), as assessed by the ΔlogK and A600/C values according to the Kumada’s classification, implying that these humic substances might have faster turnover times but strongly contribute to soil organic matter formation in this subalpine forest.

Phosphorus Fractionation in Soils Fertilized with Recycled Phosphorus Products

Phosphorus (P) will be exhausted, and its recovery and cycling will play a pivotal role in agricultural systems. Different technologies have been developed to recover P from waste materials, such as mono-incineration, acid digestion, and coprecipitation of P from wastewaters. The aim of this study was to assess the plant availability of P from different recycled P products by using a sequential chemical P fractionation of soil P and to study the fate of P applied to the soil. We evaluated the plant P availability in soils fertilized with eight recycled P products in comparison with two commercial fertilizers (triple superphosphate [TSP] and rock phosphate [Rock-P]) by means of a sequential chemical extraction of soil P and combined this data with previously published information for soil isotopically exchangeable P (IEP) and P uptake by plants (PU). We sequentially extracted inorganic P with alkaline extractants and an acid solution and analyzed the increase in P fractions caused by the application of different fertilizers. P extracted by alkali solutions was positively correlated with the IEP and with PU, whereas P extracted by the acid solution was negatively correlated with these parameters. In soils fertilized with recycled P products obtained by a chemical procedure (magnesium-ammonium-phosphate), soil P was extracted mainly by alkali extractants, while in soils fertilized with P products obtained by thermal procedures (i.e. sewage sludge ashes), soil P was extracted by the acid solution and was of low plant availability. Sequential chemical fractionation of soil P is suitable for characterizing the plant availability of P from recycled P products. The increase in the alkali soluble fraction in soil characterizes the portion of P available to plants, while the acid soluble fraction characterizes the recalcitrant portion. Phosphorus from fertilizers obtained by chemical procedures, like magnesium-ammonium-phosphate, is mainly extracted by alkali solutions and is comparable to water-soluble P fertilizers, while P from products obtained by thermal processes is mainly extracted by acid solutions and remains mostly unavailable to plants.

Investigation of cell wall polysaccharides from flour made with waste peel from unripe banana (Musa sapientum) biomass.

The peel from unripe banana biomass is an agroindustrial waste. The present study aimed: (i) to extract pectin from enzymatically-treated waste peel from unripe banana biomass (WPUBB) using a Box-Behnken design to optimize the extraction conditions (temperature, pH and extraction time) and obtain a maximum yield and (ii) to fractionate the polysaccharides from WPUBB employing sequential extractions using different solvents. The optimized product was obtained at 86 °C, pH 2.00, for 6h and it presented a yield of 11.63%. The optimized product had low galacturonic acid content and a high amount of glucose (82.3%), suggesting the presence of starch (as confirmed by the bi-dimensional heteronuclear single quantum coherence NMR spectrum). All of the fractionated polysaccharides had a high glucose content. Low amounts of pectin were found in the water, chelating and diluted alkali-soluble fractions. The fractions extracted using NaOH indicated the presence of glucuronoarabinoxylans. Glucose was the main monosaccharide found in all the fractions extracted from the WPUBB. Although the present study suggests that WPUBB is still not suitable for pectin extraction using current technologies, other compounds, such as resistant starch and glucuronoarabinoxylans, were found, suggesting that WPUBB could be used in the development of food formulations. © 2019 Society of Chemical Industry.

Deletion of admB gene encoding a fungal ADAM affects cell wall construction in Aspergillus oryzae.

Mammals possess a unique signaling system based on the proteolytic mechanism of a disintegrin and metalloproteinases (ADAMs) on the cell surface. We found two genes encoding ADAMs in Aspergillus oryzae and named them admA and admB. We produced admA and admB deletion strains to elucidate their biological function and clarify whether fungal ADAMs play a similar role as in mammals. The ∆admA∆admB and ∆admB strains were sensitive to cell wall-perturbing agents, congo red, and calcofluor white. Moreover, the two strains showed significantly increased weights of total alkali-soluble fractions from the mycelial cell wall compared to the control strain. Furthermore, ∆admB showed MpkA phosphorylation at lower concentration of congo red stimulation than the control strain. However, the MpkA phosphorylation level was not different between ∆admB and the control strain without the stimulation. The results indicated that A. oryzae AdmB involved in the cell wall integrity without going through the MpkA pathway.

The combined effect of ultrasound and enzymatic treatment on the nanostructure, carotenoid retention and sensory properties of ready-to-eat carrot chips

Fat-free crispy carrot snacks, could be an interesting proposal for consumers eager to increase their vegetable consumption, if the carotenoids naturally occurring in carrots could be retained during the drying processes used in their production. In an attempt to enhance carotenoid retention during the snacks production, ultrasound (US) and enzymatic treatment (EN) were applied as pre-treatment operations. Carrot slices were first sonicated for 20 min (25 kHz, 0.4 W/cm2), and then soaked in a light sucrose solution (110 g/L) with or without pectin lyase enzyme (2 g/L), and finally were conventionally dried to a crispy state. Final product quality was assessed, paying attention to the carotenoid content, and changes in molecular pectin structure. Both the applied pre-treatments caused transformations of diluted alkali soluble pectin fraction in the form of shortening the skeleton length. Moreover, a decrease in the diameter of pectin polymers was noticed for samples treated with ultrasound, whereas enzyme action resulted opposite alteration. The US turned out to be a less effective factor in enhancing carotenoid retention of dried carrot chips than the EN; however, their simultaneous application not only had a positive effect on carotenoid retention, but also led to a higher sensory appreciation of the product colour.

Nutrient Distribution and Bioavailability in a Tropical Microtidal Estuary, Southwest India

ABSTRACT Renjith, K.R.; Joseph, M.M.; Ratheesh Kumar, C.S.; Manju, M.N., and Chandramohanakumar, N., 2016. Nutrient distribution and bioavailability in a tropical microtidal estuary, southwest India. This study estimates the spatial and seasonal variations of phosphorus and nitrogen fractions in the surface sediments of Cochin Estuary to assess their bioavailability and the factors governing biogeochemical distribution. Seasonal variations of the dissolved nutrients suggest that phosphorous buffering activity is very high in the estuary, and there could be a nitrogen limitation in the absence of any external input. Iron-bound and calcium-bound inorganic fractions were the major forms of sedimentary phosphorus in the central estuary. Upstream regions were characterised by higher proportions of organic phosphorus, mainly as alkali-soluble fractions. Bioavailable fractions ranged from 2.61% to 90.43% of total phosphorus and show a significant increase during the lean pre-monsoon period. This increase, which ...

HUMIFIED FRACTION OF ORGANIC MATTER DUE TO PLANT MIXTURE CULTIVATION

ABSTRACT - The aim of this study was to assess the organic matter changes in quantity and quality, particularly of the humic fraction in the surface layer (0-20 cm), of a Typic Plinthustalf soil under different management of plant mixtures used as green manure for mango (Mangifera indica L.) crops. The plant mixtures, which were seeded between rows of mango trees, were formed by two groups of leguminous and non -leguminous plants. Prior to sowing, seeds were combined in different proportions and compositions constituting the following treatments: 100% non-leguminous species (NL); 100% leguminous species (L); 75% L and 25% NL; 50% L and 50% NL; 25% L and 75% NL; and 100% spontaneous vegetation, considered a control. The plant mixtures that grew between rows of mango trees caused changes in the chemical composition of the soil organic matter, especially for the treatments 50% L and 50% NL and 25% L and 75% NL, which increased the content of humic substances in the soil organic matter. However, the treatment 25% L and 75% NL was best at minimising loss of total organic carbon from the soil. The humic acids studied have mostly aliphatic characteristics, showing large amounts of carboxylic and nitrogen groups and indicating that most of the organic carbon was formed by humic substances, with fulvic acid dominating among the alkali soluble fractions.

Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost

This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100–6000mgcarbonL−1. 13C CPMAS-NMR and GC–MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS 13CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass.GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R2=−0.85; p<0.01, n=6).

Co-Production of Fungal Biomass Derived Constituents and Ethanol from Citrus Wastes Free Sugars without Auxiliary Nutrients in Airlift Bioreactor

The potential of two zygomycetes fungi, Mucor indicus and Rhizopus oryzae, in assimilating citrus waste free sugars (CWFS) and producing fungal chitosan, oil, and protein as well as ethanol was investigated. Extraction of free sugars from citrus waste can reduce its environmental impact by decreasing the possibility of wild microorganisms growth and formation of bad odors, a typical problem facing the citrus industries. A total sugar concentration of 25.1 g/L was obtained by water extraction of citrus waste at room temperature, used for fungal cultivation in shake flasks and airlift bioreactor with no additional nutrients. In shake flasks cultivations, the fungi were only able to assimilate glucose, while fructose remained almost intact. In contrast, the cultivation of M. indicus and R. oryzae in the four-liter airlift bioreactor resulted in the consumption of almost all sugars and production of 250 and 280 g fungal biomass per kg of consumed sugar, respectively. These biomasses correspondingly contained 40% and 51% protein and 9.8% and 4.4% oil. Furthermore, the fungal cell walls, obtained after removing the alkali soluble fraction of the fungi, contained 0.61 and 0.69 g chitin and chitosan per g of cell wall for M. indicus and R. oryzae, respectively. Moreover, the maximum ethanol yield of 36% and 18% was obtained from M. indicus and R. oryzae, respectively. Furthermore, that M. indicus grew as clump mycelia in the airlift bioreactor, while R. oryzae formed spherical suspended pellets, is a promising feature towards industrialization of the process.