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PubMed2004

Isolation, identification, and selection of lactic acid bacteria from alfalfa sprouts for competitive inhibition of foodborne pathogens.

Several studies have investigated the control of pathogens on alfalfa sprouts, and some treatments have been shown to be effective in reducing pathogen populations. However, control methods investigated thus far only provide pathogen control at a given point in the sprouting process and can affect germination. Competitive inhibition of pathogens with lactic acid bacteria might provide pathogen control throughout the sprouting process and up to consumption. The purpose of this study was to isolate and identify lactic acid bacteria from alfalfa sprouts to inhibit the growth of foodborne pathogens. Fifty-eight lactic acid bacteria isolates were obtained from alfalfa seeds and sprouts. These isolates were evaluated for inhibitory action against Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes by agar spot tests. All pathogens were inhibited by 32 (55%) of the isolates, S. enterica by 56 (97%), E. coli O157:H7 by 49 (84%), and L. monocytogenes by 41 (71%). The isolates were identified by the Analytical Profile Index evaluation of carbohydrate utilization. Isolates obtained from a sample of alfalfa seeds and identified as Lactococcus lactis subsp. lactis showed zones of inhibition of 4.0 mm or greater for all pathogens. One of these isolates, Lactococcus lactis subsp. lactis (L7), and an isolate previously obtained, Pediococcus acidilactici (D3), were evaluated for competitive inhibition of S. enterica, E. coli O157:H7, and L. monocytogenes in deMan Rogosa Sharpe agar and broth. Pathogen populations were significantly reduced by day 5. The selected isolates will be further evaluated in future studies for inhibitory action toward S. enterica, E. coli O157:H7, and L. monocytogenes during sprouting.

Antibiosis↗

PubMed2006

Detection of Escherichia coli in packaged alfalfa sprouts with an electronic nose and an artificial neural network.

A rapid method for the detection of Escherichia coli (ATCC 25922) in packaged alfalfa sprouts was developed. Volatile compounds from the headspace of packaged alfalfa sprouts, inoculated with E. coli and incubated at 10 degrees C for 1, 2, and 3 days, were collected and analyzed. Uninoculated sprouts were used as control samples. An electronic nose with 12 metal oxide electronic sensors was used to monitor changes in the composition of the gas phase of the package headspace with respect to volatile metabolites produced by E. coli. The electronic nose was able to differentiate between samples with and without E. coli. To predict the number of E. coli in packaged alfalfa sprouts, an artificial neural network was used, which included an input layer, a hidden layer, and an output layer, with a hyperbolic tangent sigmoidal transfer function in the hidden layer and a linear transfer function in the output layer. The network was shown to be capable of correlating voltametric responses with the number of E. coli. A good prediction was possible, as measured by a regression coefficient (R2 = 0.903) between the actual and predicted data. In conjunction with the artificial neural network, the electronic nose proved to have the ability to detect E. coli in packaged alfalfa sprouts.

Biosensing Techniques↗

PubMed2000

Clones of pea aphid, Acyrthosiphon pisum (Hemiptera: aphididae) distinguished using genetic markers, differ in their damaging effect on a resistant alfalfa cultivar.

CUF 101, a resistant cultivar of alfalfa, was exposed to 15 clones of Acyrthosiphon pisum Harris collected from alfalfa fields in three regions of France (east, south, central west) to determine whether the level of resistance varied across the different clones. The survival of alfalfa seedlings infested at the cotyledon stage was assessed using a standardized method. Although no difference in seedling mortality was detected between clones grouped by region, there was a significant variation among the 15 pea aphid clones. In particular, two clones of southern origin were more aggressive. In addition, the different pea aphid clones were characterized using allozyme and RAPD-PCR markers. Among the 15 clones, seven allozyme genotypes (plus one when adding colour polymorphism) and 12 RAPD-PCR genotypes were distinguished. The two southern clones differing by their aggressiveness on the resistant alfalfa belonged to the same allozyme and RAPD genotype which was distinct from the other pea aphid clones. Our results reinforce the need to take into account aphid genetic diversity in breeding programmes for resistance in cultivated plants.

Agriculture↗

PubMed2002

Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa (Medicago sativa L.).

Herbage yield of alfalfa (Medicago sativa L.) depends on forage management or environmental conditions that change C and N resource acquisition, and endogenous plants factors such as root organic reserves and number of active meristems. The aim of this work is to study the influence of two sowing dates in summer (12 July or 9 August), N fertilization (0 or 100 kg ha(-1)) and/or irrigation applied during the first year of alfalfa establishment on (i) the accumulation of N organic reserves (soluble proteins and more specifically vegetative storage protein) in taproots during autumn, (ii) the number of crown axillary meristems present at the end of winter and (iii) the dynamics of spring shoot growth. Delaying the sowing date for one month reduced root growth and root N storage, especially vegetative storage proteins (VSP) during autumn. Irrespective of sowing dates, N fertilization did not affect root biomass, number of crown buds, total root N, root soluble protein or VSP concentrations. By contrast, water deficiency during alfalfa establishment in the early summer reduced both root growth and N reserve accumulation. When spring growth resumed, there is a significant linear relationship between leaf area development and soluble protein and VSP concentrations in taproots, and also the number of crown buds. The results showed that an early sowing date and adequate water status during the summer allowed alfalfa plants to accumulate N reserves by increasing taproot mass and soluble protein concentrations, especially VSPs. This resulted in rapid shoot regrowth rates the following spring.

Carbon↗

PubMed2001

Overexpression of malate dehydrogenase in transgenic alfalfa enhances organic acid synthesis and confers tolerance to aluminum.

Al toxicity is a severe impediment to production of many crops in acid soil. Toxicity can be reduced through lime application to raise soil pH, however this amendment does not remedy subsoil acidity, and liming may not always be practical or cost-effective. Addition of organic acids to plant nutrient solutions alleviates phytotoxic Al effects, presumably by chelating Al and rendering it less toxic. In an effort to increase organic acid secretion and thereby enhance Al tolerance in alfalfa (Medicago sativa), we produced transgenic plants using nodule-enhanced forms of malate dehydrogenase and phosphoenolpyruvate carboxylase cDNAs under the control of the constitutive cauliflower mosaic virus 35S promoter. We report that a 1.6-fold increase in malate dehydrogenase enzyme specific activity in root tips of selected transgenic alfalfa led to a 4.2-fold increase in root concentration as well as a 7.1-fold increase in root exudation of citrate, oxalate, malate, succinate, and acetate compared with untransformed control alfalfa plants. Overexpression of phosphoenolpyruvate carboxylase enzyme specific activity in transgenic alfalfa did not result in increased root exudation of organic acids. The degree of Al tolerance by transformed plants in hydroponic solutions and in naturally acid soil corresponded with their patterns of organic acid exudation and supports the concept that enhancing organic acid synthesis in plants may be an effective strategy to cope with soil acidity and Al toxicity.

Adaptation, Physiological↗

PubMed2001

Effects of neem-based and chemical insecticides on some arthropods in alfalfa.

In this study, we tested the effects of two different doses of neem (azadirachtin) on the alfalfa weevil, Hypera variabilis Hbst. (Coleoptera: Curculionidae), aphids and predators (Coccinellids, anthocorids, chrysopids and spiders) and compared the effects with those of a broad spectrum insecticide (malathion) in a controlled experiment in 1998 and 1999. Malathion treatments reduced alfalfa weevil densities significantly (p < 0.01) by 77.9 and 87.4% in 1998 and 1999, respectively. Alfalfa weevil numbers in the low dose neem-treated plots were lower by 45.2% in 1998 and 50.2% in 1999. There were 45.3% fewer alfalfa weevils in the high dose neem-treated plots in 1999. In 1998, aphid numbers were reduced by 11.1, 25.3 and 41% in the low dose neem-treated plots, the malathion-treated plots and the high dose neem-treated plots, respectively. Aphids were more abundant in the malathion-treated plots, whereas they were fewer in the neem-treated plots compared to the control in 1999. The treatments did not have any significant effects on the total numbers of predators.

Animals↗

PubMed2005

[Alfalfa growth and its relation with soil water status in loess hilly and gully region].

This paper studied the dynamics of alfalfa growth and its relation with the excessive depletion and resumption of soil water in loess hilly and gully region. The results showed that alfalfa could grow in this region for 10 years, being most flourishing at the forth and fifth year, but declined gradually because of the excessive depletion of soil water. From 0 to 35 cm above ground, the stem biomass was higher than the leaf biomass, and the ratio of stem to leaf was 1.7:1; at 40 cm above ground, the biomass of stem and leaf was equal; and from 45 to 90 cm above ground, the leaf biomass was higher than the stem biomass, with the ratio of leaf to stem 1.42:1. The soil dry layer was not distinct in first two years of alfalfa growth, but getting thicker with time, being from 110 cm in third year to 260 cm in seventh year, with a 4.6%-6.2% of soil water content. It took 5 years for the natural resumption of soil water in degraded alfalfa grassland, and soil water content was increased with time.

Biomass↗

PubMed2005

[Dynamics of soil nitrogen, phosphorus and organic matter in alfalfa-crop rotated farmland in semiarid area of Northwest China].

Pasture-crop rotation is regarded as a key planting system in the semiarid area of China's Loess Plateau. This paper studied the dynamics of soil nitrogen, phosphorus and organic matter within the two years of alfalfa-crop rotation. The results showed that in comparing with continuous alfalfa planting, alfalfa-crop rotation induced a decline of soil total nitrogen and organic matter contents by 5.4% and 19.5%, and 46.8% and 28.2%, respectively, in the first and second year, but no significant difference was found in soil total phosphorus. Soil nutrient availability was improved due to the rotation. In the first and second year of rotation, soil nitrate nitrogen and available phosphorus contents increased by 15.5% and 159.1%, and 44.5% and 48.0%, respectively. Planting spring wheat could maintain soil fertility, the second was fallow and planting potato, while planting corn accelerated the depletion of soil total nitrogen, organic matter and available phosphorus. As a result, in the alfalfa-crop rotation, planting spring wheat could be more available to the maintenance of soil fertility.

Biomass↗

PubMedDate not supplied

[Symbiosis between the nodule bacterium Sinorhizobium meliloti and alfalfa (Medicago sativa) under salinization conditions].

Two hundred forty-three isolates of alfalfa nodule bacteria (Sinorhizobium meliloti) were obtained from legume nodules and soils sampled in the northern Aral region, experiencing secondary salinization. Isolates obtained from nodules (N isolates) were significantly more salt-tolerant than those from soils (S isolates) when grown in a liquid medium with 3.5% NaCl. It was found that wild species of alfalfa, melilot, and trigonella preferably formed symbioses with salt-tolerant nodule bacteria in both salinized and nonsalinized soils. Only two alfalfa species, Medicago falcata and M. trautvetteri, formed efficient symbioses in soils contrasting in salinity. The formation of efficient symbiosis with alfalfa in the presence of 0.6% NaCl was studied in 36 isolates (N and S) differing in salt tolerance and symbiotic efficiency. Fifteen isolates formed efficient symbioses in the presence of salt. The increase in the dry weight of the plants was 25-68% higher than in the control group. The efficiency of symbiotic interaction under salinization conditions depended on the efficiency of the isolates under standard conditions but did not correlate with the source of nodule bacteria (soil or nodule) or their salt tolerance. The results indicate that nodule bacterium strains forming efficient symbioses under salinization conditions can be found.

Adaptation, Physiological↗

PubMed1990

Cantharidin decreases in vitro digestion of alfalfa and smooth bromegrass.

Blister beetles (Coleoptera:Meloidae) containing the toxin cantharidin can be incorporated with alfalfa (Medicago sativa L) during forage conservation. Cantharidin inadvertently ingested with animal feed may cause illness or death. Little information is available on the effects of cantharidin on ruminant microbial digestion. The objective of our study was to determine cantharidin effects on digestibility of alfalfa and smooth bromegrass (Bromus inermis Leyss) by measuring in vitro digestible dry matter (IVDDM) and cell wall digestion (CWD). Alfalfa dry matter digestibility, measured after IVDDM at 48 and 96 h fermentation periods, decreased as cantharidin concentration increased. Increasing cantharidin concentration also significantly reduced IVDDM of smooth bromegrass at 24 and 96 h digestion time. The CWD of alfalfa and smooth bromegrass decreased as cantharidin concentration increased. These results indicate that ingestion of cantharidin by ruminants may decrease microbial digestion of fibrous feeds and therefore may decrease the efficiency of feed utilization by ruminants.

Animals↗

PubMed1979

Effect of dietary alfalfa, pectin, and wheat bran on azoxymethane-or methylnitrosourea-induced colon carcinogenesis in F344 rats.

The effect of dietary alfalfa, pectin, and wheat bran on colon carcinogenesis was studied in female inbred F344 rats. Weanling rats were fed semipurified diets containing 0 or 15% alfalfa, pectin, or wheat bran. At 7 weeks of age, all animals except controls were given azoxymethane (AOM) sc at a dose rate of 8 mg/kg body weight/week for 10 weeks or methylnitrosourea (MNU) intrarectally at a dose rate of 2 mg/rat twice a week for 3 weeks. The AOM-treated group was autopsied 40 weeks and the MNU-treated group 30 weeks after the first injection of the carcinogen. No tumors were observed in the colon or other organs of untreated rats fed the various diets. The animals fed the alfalfa diet and treated with MNU had a higher incidence of colon tumors than did those fed the control diet or the diets containing pectin or wheat bran. The incidence of MNU-induced colon tumors did not differ between the animals fed the control diet or the diets containing pectin or wheat bran. However, the incidence of AOM-induced colon tumors in rats fed diets containing pectin or wheat bran was lower than that in rats fed the control diet or the alfalfa diet. These results thus indicate that the effect of fiber in colon carcinogenesis depends on the type of fiber and, possibly, the fiber's mode of action.

Animals↗

PubMedDate not supplied

Extraction of light filth from whole leaves of alfalfa, lemon balm, papaya, and spearmint: collaborative study.

Results are reported for a collaborative study to extend AOAC method 44.A06-44.A08 to extraction of light filth from whole leaves of alfalfa, lemon balm, papaya, and spearmint. A 5 g (spearmint) or 10 g (alfalfa, lemon balm, papaya) test portion is defatted with isopropanol in a simple reflux apparatus. Rat hairs, insect fragments, and whole insects are isolated by wet sieving on a No. 230 sieve, a deaerating boil in 40% isopropanol, and flotation with mineral oil-heptane (85 + 15) from Tween 80-Na4EDTA (1 + 1) and 40% isopropanol in a Wildman trap flask. Each product was spiked at a different level. For rat hairs, recoveries averaged 82.2% from alfalfa, 88.9% from lemon balm, 80.6% from papaya, and 79.6% from spearmint. Recoveries of whole or equivalent insects from these products averaged 66.1, 218.8, 69.4, and 85.4%, respectively; recoveries of insect fragments from these products averaged 89.6, 94.4, 94.1, and 88.1%, respectively. The method has been adopted official first action for extraction of light filth from whole leaves of alfalfa, papaya, and spearmint. The extension of the method to lemon balm was not recommended because of interferences by intrinsic whole insects, which were the same species as the spike material.

Animals↗

PubMed1997

Comparison of maize and alfalfa silages on milk production, milk composition and blood components of dairy cows.

Twenty multiparous Friesian cows, 60 to 100 days postpartum, were allotted to two groups of 10 cows according to calving date, lactation number, and daily milk production and were assigned randomly to one of two diets in a crossover design experiment. The control diet (maize diet) was 55% maize silage (dry basis), 20% soybean meal, 22% ground maize, and 3% mineral and vitamin mix. The treatment diet (alfalfa diet) was 55% alfalfa silage, 10% soybean meal, 32% ground maize, and 3% mineral and vitamin mix. The two diets contained similar quantities of crude protein and metabolizable energy. The diets were offered individually as total mixed rations in two equal portions at 09:00 and 20:00 h in amounts to achieve ad libitum intake. The two groups of cows were allowed exercise in an open lot without shade from 11:00 to 16:30 h and 22:00 to 05:30 h. The cows were milked daily at 06:00 and 17:00 h. The dry matter, metabolizable energy and crude protein intakes, milk production, and milk fat, protein, lactose, total solids and solids not fat contents, as well as milk fat and protein yields and body condition score, were not significantly affected when maize silage was given to lactating cows, compared with that of cows given alfalfa silage. No differences were observed in blood serum concentrations of glucose, total protein, albumin, urea, triglycerides, cholesterol, Na, K, Ca, P and Mg between maize and alfalfa silages.

Animal Feed↗

PubMed1965

STUDIES ON CARBOHYDRATE-METABOLIZING ENZYMES. THE HYDROLYSIS OF ALPHA-GLUCOSIDES, INCLUDING NIGEROSE, BY EXTRACTS OF ALFALFA AND OTHER HIGHER PLANTS.

1. Enzyme preparations from 11 plant sources, from yeast and from the protozoan Tetrahymena pyriformis show nigerase activity, which, in most preparations, was 70-90% of that towards maltose. 2. These enzyme preparations also hydrolysed isomaltose, but there was a wide variation in relative maltase to isomaltase activity. 3. The maltase and nigerase activities of alfalfa and tomato preparations could not be differentiated by heat inactivation or inhibitor methods. However, with turanose used as a competitive inhibitor, evidence suggesting that maltose and nigerose are hydrolysed at different catalytically active sites in the alfalfa preparation was obtained. 4. It is probable that the alfalfa alpha-glucosidase exists as a mixture of isoenzymes.

Biochemical Phenomena↗

PubMed1995

High-affinity RNA-binding domains of alfalfa mosaic virus coat protein are not required for coat protein-mediated resistance.

A virus-based vector was used for the transient expression of the alfalfa mosaic virus coat protein (CP) gene in protoplasts and plants. The accumulation of wild-type CP conferred strong protection against subsequent alfalfa mosaic virus infection, enabling the efficacy of CP mutants to be determined without developing transgenic plants. Expression of the CP mRNA alone without CP accumulation conferred weaker protection against infection. The activity of the N-terminal mutant CPs in protection did not correlate with their activities in genome activation. The activity of a C-terminal mutant suggested that encapsidation did not have a role in protection. Our results indicate that interaction of the CP with alfalfa mosaic virus RNA is not important in protection, thereby leaving open the possibility that interactions with host factors lead to protection.

Alfalfa mosaic virus↗

PubMed2005

Industrial process proteomics: alfalfa protein patterns during wet fractionation processing.

A proteome reference map of major soluble proteins from Medicago sativa (alfalfa) leaves and stems has been established for the first time. Among 195 spots analyzed by mass spectrometry and N-terminal Edman sequencing, 117 spots were unambiguously identified, representing 87 different proteins. Of these 87 proteins, 13 proteins were directly identified from the partial genome of Medicago sativa, 30 from expressed sequenced tags (ESTs) of the model legume Medicago truncatula and 44 from closely relative species by a cross-species protein identification method. The proteome map of Medicago sativa was then set as a reference to study the major high protein content products that are generated during the wet fractionation process of alfalfa green biomass. Using two-dimensional electrophoresis, we studied the variation of the protein patterns at different steps of the industrial-scale process. We clearly show that the process induces significant changes including chemical modifications, proteolytic events, and heat-shock protein responses. Strikingly, a certain level of cellular regulation is conserved during biomass processing, as exemplified by the induction of some heat shock proteins. Finally, all the results obtained in this proteomic study may help to identify novel products and to improve process designs in alfalfa biomass plants.

Chemical Fractionation↗

PubMed1993

Stress responses in alfalfa (Medicago sativa L.). XVIII: Molecular cloning and expression of the elicitor-inducible cinnamic acid 4-hydroxylase cytochrome P450.

We have isolated cDNA clones encoding a novel class of plant cytochrome P450 by screening an alfalfa cDNA expression library with an antibody against an avocado P450 (CYP73A1) that is expressed during fruit ripening but that has not yet been ascribed an in vivo activity. The cDNAs encode a polypeptide of M(r) 58,000, pI 9.3, containing sequence similarity (25 to 31% overall at the amino acid level) to the avocado P450 and mammalian, yeast, and bacterial P450s, particularly in the presumed heme binding region. Expression studies in yeast confirmed that the P450 clones encode cinnamic acid 4-hydroxylase (CA4H), a key enzyme of the phenylpropanoid pathway in plants. CA4H is encoded by a small gene family in alfalfa, which does not appear to contain homologs of the avocado P450. CA4H transcripts are strongly induced by fungal elicitor at the onset of accumulation of isoflavonoid phytoalexins in alfalfa cell suspension cultures.

Amino Acid Sequence↗

PubMed1996

Affinity chromatography, substrate/product specificity, and amino acid sequence analysis of an isoflavone O-methyltransferase from alfalfa (Medicago sativa L.).

Isoflavone O-methyltransferase (IOMT) is a key enzyme in the biosynthesis of the phytoalexin medicarpin in alfalfa. In vivo, the B-ring 4'-hydroxyl group of the isoflavone daidzein is methylated. Surprisingly, the O-methyltransferase activity measured in vitro preferentially methylates the A-ring 7-hydroxyl group, a reaction that probably does not occur in vivo. To resolve this anomaly, we are attempting to clone the alfalfa IOMT. A substrate-based affinity chromatographic system was developed to purify the enzyme (molecular weight 41 kDa) to near homogeneity. Four internal peptide sequences were obtained from the purified protein, one of which has high (72%) sequence identity to a region of a catechol O-methyltransferase from barley. All four internal peptides, respectively, have about 55% amino acid sequence identity to four regions of 6alpha-hydroxymaackiain 3-O-methyltransferase from Pisum sativum, but have no sequence identity to alfalfa caffeic acid 3-O-methyltransferase or chalcone 2'-O-methyltransferase. The purified IOMT has substrate specificity toward isoflavones with a free 7-hydroxyl group, but can also methylate the 5-hydroxyl group of genistein.

Amino Acid Sequence↗