Fitness of Salmonella enterica serovar Thompson in the cilantro phyllosphere. (1/23)

The epiphytic fitness of Salmonella enterica was assessed on cilantro plants by using a strain of S. enterica serovar Thompson that was linked to an outbreak resulting from cilantro. Salmonella serovar Thompson had the ability to colonize the surface of cilantro leaves, where it was detected by confocal laser scanning microscopy (CLSM) at high densities on the veins and in natural lesions. The population sizes of two common colonizers of plant surfaces, Pantoea agglomerans and Pseudomonas chlororaphis, were 10-fold higher than that of the human pathogen on cilantro incubated at 22 degrees C. However, Salmonella serovar Thompson achieved significantly higher population levels and accounted for a higher proportion of the total culturable bacterial flora on cilantro leaves when the plants were incubated at warm temperatures, such as 30 degrees C, after inoculation, indicating that the higher growth rates exhibited by Salmonella serovar Thompson at warm temperatures may increase the competitiveness of this organism in the phyllosphere. The tolerance of Salmonella serovar Thompson to dry conditions on plants at 60% relative humidity was at least equal to that of P. agglomerans and P. chlororaphis. Moreover, after exposure to low humidity on cilantro, Salmonella serovar Thompson recovered under high humidity to achieve its maximum population size in the cilantro phyllosphere. Visualization by CLSM of green fluorescent protein-tagged Salmonella serovar Thompson and dsRed-tagged P. agglomerans inoculated onto cilantro revealed that the human pathogen and the bacterial epiphyte formed large heterogeneous aggregates on the leaf surface. Our studies support the hypothesis that preharvest contamination of crops by S. enterica plays a role in outbreaks linked to fresh fruits and vegetables.  (+info)

Water-soluble constituents of coriander. (2/23)

From the water-soluble portion of the methanol extract of coriander (fruit of Coriandrum sativum L.), which has been used as a spice and medicine since antiquity, 33 compounds, including two new monoterpenoids, four new monoterpenoid glycosides, two new monoterpenoid glucoside sulfates and two new aromatic compound glycosides were obtained. Their structures, were clarified by spectral investigation.  (+info)

Production of autoinducer 2 in Salmonella enterica serovar Thompson contributes to its fitness in chickens but not on cilantro leaf surfaces. (3/23)

Food-borne illness caused by Salmonella enterica has been linked traditionally to poultry products but is associated increasingly with fresh fruits and vegetables. We have investigated the role of the production of autoinducer 2 (AI-2) in the ability of S. enterica serovar Thompson to colonize the chicken intestine and the cilantro phyllosphere. A mutant of S. enterica serovar Thompson that is defective in AI-2 production was constructed by insertional mutagenesis of luxS. The population size of the S. enterica serovar Thompson parental strain was significantly higher than that of its LuxS(-) mutant in the intestine, spleen, and droppings of chicks 12 days after their oral inoculation with the strains in a ratio of 1:1. In contrast, no significant difference in the population dynamics of the parental and LuxS(-) strain was observed after their inoculation singly or in mixtures onto cilantro plants. Digital image analysis revealed that 54% of S. enterica serovar Thompson cells were present in large aggregates on cilantro leaves but that the frequency distributions of the size of aggregates formed by the parental strain and the LuxS(-) mutant were not significantly different. Carbon utilization profiles indicated that the AI-2-producing strain utilized a variety of amino and organic acids more efficiently than its LuxS(-) mutant but that most sugars were utilized similarly in both strains. Thus, inherent differences in the nutrients available to S. enterica in the phyllosphere and in the chicken intestine may underlie the differential contribution of AI-2 synthesis to the fitness of S. enterica in these environments.  (+info)

A multifunctional acyl-acyl carrier protein desaturase from Hedera helix L. (English ivy) can synthesize 16- and 18-carbon monoene and diene products. (4/23)

A desaturase with 83% sequence identity to the coriander delta(4)-16:0-ACP desaturase was isolated from developing seeds of Hedera helix (English ivy). Expression of the ivy desaturase in Arabidopsis resulted in the accumulation of 16:1delta(4) and its expected elongation product 18:1delta(6) (petroselinic acid). Expression in Escherichia coli resulted in the accumulation of soluble, active protein that was purified to apparent homogeneity. In vitro assays confirmed delta(4) desaturation with 16:0-ACP; however, with 18:0-acyl acyl carrier protein (ACP) desaturation occurred at the delta(9) position. The ivy desaturase also converted 16:1delta(9)-ACP and 18:1delta(9)-ACP to the corresponding delta(4,9) dienes. These data suggest at least two distinct substrate binding modes, one placing C4 at the diiron active site and the other placing C9 at the active site. In the latter case, 18:0 would likely bind in an extended conformation as described for the castor desaturase with 9-carbons accommodated in the cavity beyond the dirron site. However, delta(4) desaturation would require the accommodation of 12 carbons for C16 substrates or 14 carbons for C18 substrates. The amino acids lining the substrate binding cavity of ivy and castor desaturases are conserved except for T117R and P179I (castor/ivy). Paradoxically, both substitutions, when introduced into the castor desaturase, favored the binding of shorter acyl chains. Thus, it seems likely that delta(4) desaturation would require a non-extended, perhaps U-shaped, substrate conformation. A cis double bond may facilitate the initiation of such a non-extended conformation in the monounsaturated substrates. The multifunctional properties of the ivy desaturase make it well suited for further dissection of the determinants of regiospecificity.  (+info)

Genomic structures and characterization of the 5'-flanking regions of acyl carrier protein and Delta4-palmitoyl-ACP desaturase genes from Coriandrum sativum. (5/23)

The seed-specific or seed-predominant promoters of acyl carrier protein (Cs-ACP1) and Delta4-palmitoyl-acyl carrier protein desaturase (Cs-4PAD) genes, which are involved in the biosynthesis of petroselinic acid, were isolated from coriander (Coriandrum sativum) and analyzed in coriander endosperms and transgenic Arabidopsis. The expression of Cs-ACP1 and Cs-4PAD genes was coordinately regulated during seed development.  (+info)

Accumulation of calcium in the centre of leaves of coriander (Coriandrum sativum L.) is due to an uncoupling of water and ion transport. (6/23)


Essential oils in the treatment of intestinal dysbiosis: A preliminary in vitro study. (7/23)

INTRODUCTION: Dysbiosis is associated with a number of gastrointestinal and systemic disorders. There is a need for selectively acting antimicrobial agents capable of inhibiting the growth of potentially pathogenic microorganisms, or those found to be out of balance, while not negatively impacting the bulk gastrointestinal tract microflora. OBJECTIVE: The purpose of this in vitro study is to examine the potential of a selection of essential oils as agents to treat dysbiosis. MATERIALS AND METHODS: Eight essential oils were examined using the agar dilution method, including Carum carvi, Citrus aurantium var. amara, Foeniculum vulgare dulce, Illicium verum, Lavandula angustifolia, Mentha arvensis, Mentha x piperita, and Trachyspermum copticum. Doubling dilutions of the essential oils were tested against 12 species of intestinal bacteria, which represent the major genera found in the human gastrointestinal tract (GIT). RESULTS: Carum carvi, Lavandula angustifolia, Trachyspermum copticum, and Citrus aurantium var. amara essential oils displayed the greatest degree of selectivity, inhibiting the growth of potential pathogens at concentrations that had no effect on the beneficial bacteria examined. CONCLUSION: The most promising essential oils for the treatment of intestinal dysbiosis are Carum carvi, Lavandula angustifolia, Trachyspermum copticum, and Citrus aurantium var. amara. The herbs from which these oils are derived have long been used in the treatment of gastrointestinal symptoms and the in vitro results of this study suggest that their ingestion will have little detrimental impact on beneficial members of the GIT microflora. More research is needed, however, to investigate tolerability and safety concerns, and verify the selective action of these agents.  (+info)

Potential of coriander (Coriandrum sativum) oil as a natural antimicrobial compound in controlling Campylobacter jejuni in raw meat. (8/23)

Twelve essential oils were tested in vitro for antimicrobial activities against several strains of Campylobacter jejuni, a pathogen causing food-borne diseases worldwide. Using disk diffusion and minimal inhibitory concentration determination assays, we noted that coriander oil exhibited the strongest antimicrobial activity against all tested strains. The oil had a bactericidal effect on the target bacteria. In evaluating the antimicrobial potency of coriander oil against C. jejuni on beef and chicken meat at 4 degrees C and 32 degrees C, it was found that the oil reduced the bacterial cell load in a dose-dependent manner. The type of meat and temperature did not influence the antimicrobial activity of the oil. This study indicates the potential of coriander oil to serve as a natural antimicrobial compound against C. jejuni in food.  (+info)