Pathogenesis-Related Genes of PR1, PR2, PR4, and PR5 Families Are Involved in the Response to Fusarium Infection in Garlic (Allium sativum L.)

Plants of the genus Allium developed a diversity of defense mechanisms against pathogenic fungi of the genus Fusarium, including transcriptional activation of pathogenesis-related (PR) genes. However, the information on the regulation of PR factors in garlic (Allium sativum L.) is limited. In the present study, we identified AsPR genes putatively encoding PR1, PR2, PR4, and PR5 proteins in A. sativum cv. Ershuizao, which may be involved in the defense against Fusarium infection. The promoters of the AsPR1-5 genes contained jasmonic acid-, salicylic acid-, gibberellin-, abscisic acid-, auxin-, ethylene-, and stress-responsive elements associated with the response to plant parasites. The expression of AsPR1c, d, g, k, AsPR2b, AsPR5a, c (in roots), and AsPR4a(c), b, and AsPR2c (in stems and cloves) significantly differed between garlic cultivars resistant and susceptible to Fusarium rot, suggesting that it could define the PR protein-mediated protection against Fusarium infection in garlic. Our results provide insights into the role of PR factors in A. sativum and may be useful for breeding programs to increase the resistance of Allium crops to Fusarium infections.

Comparison of bacterial and archaeal communities in two fertilizer doses and soil compartments under continuous cultivation system of garlic

Soil microbial communities are affected by interactions between agricultural management (e.g., fertilizer) and soil compartment, but few studies have considered combinations of these factors. We compared the microbial abundance, diversity and community structure in two fertilizer dose (high vs. low NPK) and soil compartment (rhizosphere vs. bulk soils) under 6-year fertilization regimes in a continuous garlic cropping system in China. The soil contents of NO3- and available K were significantly higher in bulk soil in the high-NPK. The 16S rRNA gene-based bacterial and archaeal abundances were positively affected by both the fertilizer dose and soil compartment, and were higher in the high-NPK fertilization and rhizosphere samples. High-NPK fertilization increased the Shannon index and decreased bacterial and archaeal richness, whereas the evenness was marginally positively affected by both the fertilizer dose and soil compartment. Soil compartment exerted a greater effect on the bacterial and archaeal community structure than did the fertilization dose, as demonstrated by both the nonmetric multidimensional scaling and redundancy analysis results. We found that rhizosphere effects significantly distinguished 12 dominant classes of bacterial and archaeal communities, whereas the fertilizer dose significantly identified four dominant classes. In particular, a Linear Effect Size analysis showed that some taxa, including Alphaproteobacteria, Rhizobiales, Xanthomonadaceae and Flavobacterium, were enriched in the garlic rhizosphere of the high-NPK fertilizer samples. Overall, the fertilizer dose interacted with soil compartment to shape the bacterial and archaeal community composition, abundance, and biodiversity in the garlic rhizosphere. These results provide an important basis for further understanding adaptive garlic-microbe feedback, reframing roots as a significant moderating influence in agricultural management and shaping the microbial community.

Microbial niches in raw ingredients determine microbial community assembly during kimchi fermentation

Fermented foods constitute hubs of microbial consortia differentially affecting nutritional and organoleptic properties, quality, and safety. Here we show the origin source of fermentative microbes and fermentation dynamics of kimchi. We partitioned microbiota by raw ingredient (kimchi cabbage, garlic, ginger, and red pepper) to render kimchi fermented by each source-originated microbe pool and applied multi-omics (metataxonomics and metabolomics), bacterial viability, and physiochemical analyses to longitudinally collected samples. Only kimchi cabbage- and garlic-derived microbial inoculums yielded successful kimchi fermentations. The dominant fermentative microbial taxa and subsequent metabolic outputs differed by raw ingredient type: the genus Leuconostoc, Weissella, and Lactobacillus for all non-sterilized ingredients, garlic, and kimchi cabbage, respectively. Gnotobiotic kimchi inoculated by mono-, di-, and tri- isolated fermentative microbe combinations further revealed W. koreensis-mediated reversible microbial metabolic outputs. The results suggest that the raw ingredient microbial habitat niches selectively affect microbial community assembly patterns and processes during kimchi fermentation.

Trichoderma from Brazilian garlic and onion crop soils and description of two new species: Trichoderma azevedoi and Trichoderma peberdyi

Fifty four Trichoderma strains were isolated from soil samples collected from garlic and onion crops in eight different sites in Brazil and were identified using phylogenetic analysis based on combined ITS region, tef1-α, cal, act and rpb2 sequences. The genetic variability of the recovered Trichoderma species was analysed by AFLP and their phenotypic variability determined using MALDI-TOF. The strain clusters from both typing techniques coincided with the taxonomic determinations made from phylogenetic analysis. The phylogenetic analysis showed the occurrence of Trichoderma asperellum, Trichoderma asperelloides, Trichoderma afroharzianum, Trichoderma hamatum, Trichoderma lentiforme, Trichoderma koningiopsis, Trichoderma longibrachiatum and Trichoderma erinaceum, in the soil samples. We also identified and describe two new Trichoderma species, both in the harzianum clade of section Pachybasium, which we have named Trichoderma azevedoi sp. nov. and Trichoderma peberdyi sp. nov. The examined strains of both T. azevedoi (three strains) and T. peberdyi (12 strains) display significant genotypic and phenotypic variability, but form monophyletic clades with strong bootstrap and posterior probability support and are morphologically distinct from their respective most closely related species.

Detection of Fumonisins in Fresh and Dehydrated Commercial Garlic

An epidemic fungal disease caused by Fusarium proliferatum, responsible for fumonisin production (FB1, FB2, and FB3), has been reported in the main garlic-producing countries in recent years. Fumonisins are a group of structurally related toxic metabolites produced by this pathogen. The aim of this work was to establish an enzyme-linked immunosorbent assay (ELISA) procedure, mostly applied to cereals, that is suitable for fumonisin detection in garlic and compare these results to those obtained by high-performance liquid chromatography (HPLC) and screening of fresh and dehydrated garlic for toxicological risk. The results show good correlation between the two analytical methods. In fresh symptomatic garlic, fumonisin levels were higher in the basal plates than those in the portions with necrotic spots. Among the 56 commercially dehydrated garlic samples screened, three were positive by ELISA test and only one was above the limit of quantitation. The same samples analyzed by HPLC showed the presence of FB1 in trace amounts that was below the limit of quantitation; FB2 and FB3 were absent. The results are reassuring, because no substantial contamination by fumonisins was found in commercial garlic.

Green Pea and Garlic Puree Model Food Development for Thermal Pasteurization Process Quality Evaluation

Development and selection of model foods is a critical part of microwave thermal process development, simulation validation, and optimization. Previously developed model foods for pasteurization process evaluation utilized Maillard reaction products as the time-temperature integrators, which resulted in similar temperature sensitivity among the models. The aim of this research was to develop additional model foods based on different time-temperature integrators, determine their dielectric properties and color change kinetics, and validate the optimal model food in hot water and microwave-assisted pasteurization processes. Color, quantified using a* value, was selected as the time-temperature indicator for green pea and garlic puree model foods. Results showed 915 MHz microwaves had a greater penetration depth into the green pea model food than the garlic. a* value reaction rates for the green pea model were approximately 4 times slower than in the garlic model food; slower reaction rates were preferred for the application of model food in this study, that is quality evaluation for a target process of 90 °C for 10 min at the cold spot. Pasteurization validation used the green pea model food and results showed that there were quantifiable differences between the color of the unheated control, hot water pasteurization, and microwave-assisted thermal pasteurization system. Both model foods developed in this research could be utilized for quality assessment and optimization of various thermal pasteurization processes.

Multiple garlic (Allium sativum L.) microRNAs regulate the immunity against the basal rot fungus Fusarium oxysporum f. sp. Cepae

The basal plate rot fungus, Fusarium oxysporum f. sp. cepae (FOC), is the most devastating pathogen posing a serious threat to garlic (Allium sativum L.) production worldwide. MicroRNAs (miRNAs) are key modulators of gene expression related to development and defense responses in eukaryotes. However, the miRNA species associated with garlic immunity against FOC are yet to be explored. In the present study, a small RNA library developed from FOC infected resistant garlic line was sequenced to identify immune responsive miRNAs. Forty-five miRNAs representing 39 conserved and six novel sequences responsive to FOC were detected. qRT-PCR analyses further classified them into three classes based on their expression patterns in susceptible line CBT-As11 and in the resistant line CBT-As153. North-blot analyses of six selective miRNAs confirmed the qRT-PCR results. Expression studies on a selective set of target genes revealed a negative correlation with the complementary miRNAs. Furthermore, transgenic garlic plant overexpresing miR164a, miR168a and miR393 showed enhanced resistance to FOC, as revealed by decreased fungal growth and up-regulated expression of defense-responsive genes. These results indicate that multiple miRNAs are involved in garlic immunity against FOC and that the overexpression of miR164a, miR168a and miR393 can augment garlic resistance to Fusarium basal rot infection.

Source Tracking and Succession of Kimchi Lactic Acid Bacteria during Fermentation

This study aimed at evaluating raw materials as potential lactic acid bacteria (LAB) sources for kimchi fermentation and investigating LAB successions during fermentation. The bacterial abundances and communities of five different sets of raw materials were investigated using plate-counting and pyrosequencing. LAB were found to be highly abundant in all garlic samples, suggesting that garlic may be a major LAB source for kimchi fermentation. LAB were observed in three and two out of five ginger and leek samples, respectively, indicating that they can also be potential important LAB sources. LAB were identified in only one cabbage sample with low abundance, suggesting that cabbage may not be an important LAB source. Bacterial successions during fermentation in the five kimchi samples were investigated by community analysis using pyrosequencing. LAB communities in initial kimchi were similar to the combined LAB communities of individual raw materials, suggesting that kimchi LAB were derived from their raw materials. LAB community analyses showed that species in the genera Leuconostoc, Lactobacillus, and Weissella were key players in kimchi fermentation, but their successions during fermentation varied with the species, indicating that members of the key genera may have different acid tolerance or growth competitiveness depending on their respective species.

Host extract modulates metabolism and fumonisin biosynthesis by the plant-pathogenic fungus Fusarium proliferatum

Fusarium proliferatum is a common pathogen able to infect a broad range of agriculturally important crops. Recently, some evidence for genetic variance among the species genotypes in relation to their plant origin has been reported. Mycotoxin contamination of plant tissues is the most important threat caused by F. proliferatum and fumonisins B (FBs) are the principal mycotoxins synthesized. The toxigenic potential of the pathogen genotypes is variable and also the reaction of different host plant species on the infection by pathogen is different. The objective of present study was to evaluate the impact of the extracts on the growth and fumonisin biosynthesis by 32 F. proliferatum strains originating from different host species (A-asparagus, M-maize, G-garlic, PS-pea and P-pineapple), and how it changes the secondary metabolism measured by fumonisin biosynthesis. The average strain dry weight was 65.2 mg for control conditions and it reached 180.7 mg, 100.5 mg, 76.6 mg, 126.2 mg and 51.1 mg when pineapple, asparagus, maize, garlic and pea extracts were added, respectively. In the second experiment the extracts were added after 5 days of culturing of the representative group of strains, displaying diverse reaction to the extract presence. Also, the influence of stationary vs. shaken culture was examined. Mean biomass amounts for shaken cultures of 15 chosen strains were as follows: 37.4 mg of dry weight for control culture (C), 219.6 mg (P), 113 mg (A), 93.6 mg (M), 62 mg (G) and 48 mg (PS), respectively. For stationary cultures, the means were as follows: C-57.4 mg, P-355.6 mg, A-291.6 mg, M-191.1 mg, G-171.1 mg and PS-58.9 mg. Few strains showed differential growth when stationary/shaken culture conditions were applied. Almost all strains synthesized moderate amounts of fumonisins in control conditions-less than 10 ng/μL, regardless of the origin and host species. Few strains were able to produce over 100 ng/μL of FBs when pineapple extract was added, twelve strains synthesized more than 10 ng/μL under asparagus extract induction and the pea extract was the most efficient inhibitor of fumonisin biosynthesis. The general impact of the extracts on the fungal biomass amounts was similar, regardless of the host plant origin of the fungal genotypes studied. The evaluation of FBs content has shown differential reaction of some strains, which may contribute to their aggressiveness and pathogenicity.

Physical-, chemical-, and microbiological-based identification of electron beam- and γ-irradiated frozen crushed garlic

Identification of frozen crushed garlic, commercially available in the Korean market, was performed using four different analytical techniques (three screening and one confirmation). The garlic samples produced in Korea and China were irradiated (electron-beam and γ-rays) at 0, 1, 4, and 7 kGy. Non-irradiated samples showed a relatively moderate population of aerobic bacteria and yeasts/molds around 10(5) CFU/g. Irradiation treatments unequivocally reduced the microbial/fungal populations with dose increments. Microbiological screening through direct epifluorescent filter technique/aerobic plate count (DEFT/APC) method effectively differentiated the non-irradiated and irradiated samples. An electronic nose method positively differentiated the odor patterns of samples based on chemical sensing. However, photostimulated luminescence technique (PSL) exhibited poor sensitivity. Minerals separated from irradiated samples produced thermoluminescence (TL) glow curves in the specific temperature range of 150-250 °C. In conclusion, TL confirmatory analysis gave the most promising results in detecting the irradiation status of garlic samples irrespective of the production origin and type of ionizing radiation treatment.

Antifungal activity of metabolites of the endophytic fungus Trichoderma brevicompactum from garlic

The endophytic fungus strain 0248, isolated from garlic, was identified as Trichoderma brevicompactum based on morphological characteristics and the nucleotide sequences of ITS1-5.8S- ITS2 and tef1. The bioactive compound T2 was isolated from the culture extracts of this fungus by bioactivity-guided fractionation and identified as 4β-acetoxy-12,13- epoxy-Δ(9)-trichothecene (trichodermin) by spectral analysis and mass spectrometry. Trichodermin has a marked inhibitory activity on Rhizoctonia solani, with an EC50 of 0.25 μg mL(-1). Strong inhibition by trichodermin was also found for Botrytis cinerea, with an EC50 of 2.02 μg mL(-1). However, a relatively poor inhibitory effect was observed for trichodermin against Colletotrichum lindemuthianum (EC50 = 25.60 μg mL(-1)). Compared with the positive control Carbendazim, trichodermin showed a strong antifungal activity on the above phytopathogens. There is little known about endophytes from garlic. This paper studied in detail the identification of endophytic T. brevicompactum from garlic and the characterization of its active metabolite trichodermin.

Development of an efficient Agrobacterium-mediated transformation system and production of herbicide-resistant transgenic plants in garlic (Allium sativum L.)

The genetic improvement of garlic plants (Allium sativum L.) with agronomical beneficial traits is rarely achieved due to the lack of an applicable transformation system. Here, we developed an efficient Agrobacterium-mediated transformation procedure with Danyang, an elite Korean garlic cultivar. Examination of sGFP (synthetic green fluorescence protein) expression revealed that treatment with 2-(N-morpholino) ethanesulfonic acid (MES), L-cysteine and/or dithiothreitol (DTT) gives the highest efficiency in transient gene transfer during Agrobacterium co-cultivation with calli derived from the roots of in vitro plantlets. To increase stable transformation efficiency, a two-step selection was employed on the basis of hygromycin resistance and sGFP expression. Of the hygromycin-resistant calli initially produced, only sGFP-expressing calli were subcultured for selection of transgenic calli. Transgenic plantlets produced from these calli were grown to maturity. The transformation efficiency increased up to 10.6% via our optimized procedure. DNA and RNA gel-blot analysis indicated that transgenic garlic plants stably integrated and expressed the phosphinothricin acetyltransferase (PAT) gene. A herbicide spraying assay demonstrated that transgenic plants of garlic conferred herbicide resistance, whilst nontransgenic plants and weeds died. These results indicate that our transformation system can be efficiently utilized to produce transgenic garlic plants with agronomic benefits.

Characterization of a novel bipartite double-stranded RNA mycovirus conferring hypovirulence in the phytopathogenic fungus Botrytis porri

The ascomycete Botrytis porri causes clove rot and leaf blight of garlic worldwide. We report here the biological and molecular features of a novel bipartite double-stranded RNA (dsRNA) mycovirus named Botrytis porri RNA virus 1 (BpRV1) from the hypovirulent strain GarlicBc-72 of B. porri. The BpRV1 genome comprises two dsRNAs, dsRNA-1 (6,215 bp) and dsRNA-2 (5,879 bp), which share sequence identities of 62 and 95% at the 3'- and 5'-terminal regions, respectively. Two open reading frames (ORFs), ORF I (dsRNA-1) and ORF II (dsRNA-2), were detected. The protein encoded by the 3'-proximal coding region of ORF I shows sequence identities of 19 to 23% with RNA-dependent RNA polymerases encoded by viruses in the families Totiviridae, Chrysoviridae, and Megabirnaviridae. However, the proteins encoded by the 5'-proximal coding region of ORF I and by the entire ORF II lack sequence similarities to any reported virus proteins. Phylogenetic analysis showed that BpRV1 belongs to a separate clade distinct from those of other known RNA mycoviruses. Purified virions of ~35 nm in diameter encompass dsRNA-1 and dsRNA-2, and three structural proteins (SPs) of 70, 80, and 85 kDa, respectively. Peptide mass fingerprinting analysis revealed that the 80- and 85-kDa SPs are encoded by ORF I, while the 70-kDa SP is encoded by ORF II. Introducing BpRV1 purified virions into the virulent strain GarlicBc-38 of B. porri caused derivative 38T reduced mycelial growth and hypovirulence. These combined results suggest that BpRV1 is a novel bipartite dsRNA virus that possibly belongs to a new virus family.

Effect of processing and storage time on the contents of organosulfur compounds in pickled blanched garlic

The influence of processing, with and without fermentation, on the contents of organosulfur compounds, namely, γ-glutamyl peptides, S-alk(en)yl-L-cysteine sulfoxides (ACSOs), and S-allyl-L-cysteine (SAC), in pickled blanched garlic was evaluated. For each processing type, the effect of the preservation method and storage time was also analyzed. Blanching in hot water (90 °C for 5 min) hardly affected the individual organosulfur compound content. The fermentation and packing steps negatively affected the levels of all compounds except for SAC. The content of this compound increased during storage at room temperature whereas γ-glutamyl peptides and ACSOs were degraded to various extents. The pasteurization treatment itself had no significant effect on the concentrations of organosulfur compounds. Use of the corresponding fermentation brine in the case of the fermented product in conjunction with refrigerated storage was found to be the best method to preserve the levels of organosulfur compounds in pickled garlic stored for up to one year.

Fermented garlic protects diabetic, obese mice when fed a high-fat diet by antioxidant effects

This study examined the bioactivity of yeast (Saccharomyces cerevisiae)-fermented aged black garlic (FBG) on obese mice supplied a high-fat diet (HFD) and its in vitro antioxidant activity. Aged black garlic (BG) exhibits potent antioxidative effects and has been subjected to extensive research. In addition, the bioactivity of some natural products is increased by fermentation. In a preliminary test, this study found that the antioxidant activity of FBG is stronger than that of BG. Therefore, it was hypothesized that the bioactivity of BG would be increased by yeast fermentation and would be a good candidate as a nutraceutical product for improving the oxidative defense systems in older patients or patients affected by various oxidative stresses, for example, diabetes and diabetic complications. To test this hypothesis, the bioactivities of FBG in diabetic and obese mice as well as the antioxidant activity in vitro were examined. After 91 days of continuous HFD supply, the mice showed marked obesity, hyperglycemia, hyperlipemia, and liver and kidney damages. Black garlic and all 3 different doses of FBG showed favorable hepatoprotective, nephroprotective, hypolipidemic, and antiobesity effects compared with the HFD control, but no hypoglycemic effects. In particular, more favorable bioactivity against all 4 HFD-induced diabetic complications was detected in the FBG-treated groups compared with the group given equivalent doses of BG. These findings suggest that the bioactivities of BG can be improved by yeast fermentation.

Micromonospora tulbaghiae sp. nov., isolated from the leaves of wild garlic, Tulbaghia violacea

A novel actinomycete, strain TVU1(T), was isolated from leaves of the indigenous South African plant Tulbaghia violacea. Applying a polyphasic approach, the isolate was identified as a member of the genus Micromonospora. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain TVU1(T) was most closely related to Micromonospora echinospora DSM 43816(T). However, phylogenetic analysis based on gyrB gene sequences showed that strain TVU1(T) was most closely related to the type strains of Micromonospora aurantiaca and Micromonospora chalcea. DNA-DNA relatedness values between strain TVU1(T) and the type strains of M. echinospora, M. aurantiaca and M. chalcea were 7.6+/-4.5, 45.9+/-2.0 and 60.9+/-4.5 %, respectively. Strain TVU1(T) could be distinguished from the type strains of all three of these species by several physiological characteristics, such as colony colour, NaCl tolerance, growth temperature range and sole carbon source utilization pattern. Strain TVU1(T) (=DSM 45142(T)=NRRL B-24576(T)) therefore represents a novel species for which the name Micromonospora tulbaghiae sp. nov. is proposed.

Agrobacterium tumefaciens-mediated transformation of leek (Allium porrum) and garlic (Allium sativum)

Transgenic leek (Allium porrum) and garlic (Allium sativum) plants have been recovered by the selective culturing of immature leek and garlic embryos via Agrobacterium-mediated transformation using a method similar to that described by Eady et al. (Plant Cell Rep 19:376-381, 2000) for onion transformation. This method involved the use of a binary vector containing the m-gfp-ER reporter gene and nptII selectable marker, and followed the protocol developed previously for the transformation of onions with only minor modifications pertaining to the post-transformation selection procedure which was simplified to have just a single selection regime. Transgenic cultures were selected for their ability to express the m-gfp-ER reporter gene and grown in the presence of geneticin (20 mg/l). The presence of transgenes in the genome of the plants was confirmed using TAIL-PCR and Southern analysis. This is the first report of leek and "true seed" garlic transformation. It now makes possible the integration of useful agronomic and quality traits into these crops.

[Microbiological study of dehydrated garlic (Allium sativum L.) and onion (Allium cepa L.)]

A microbiological study during the process and the storage of garlic (Allium sativum L.) and onion (Allium cepa L.) dehydrated, with the additional barriers of blanching or brine immersion, was made. In all raw materials the average counts of aerobic mesophilic bacteria expressed in CFU/g ranged from 1.2 x 10(2) to 1.6 x 10(3), molds and yeasts from 60 to 1.6 x 10(3), Lactobacillus spp. and Leuconostoc mesenteroides subsp. mesenteroides between 10 and 50. Microorganisms identified were Penicillium spp., Monilia spp., Lactobacillus brevis, Leuconostoc mesenteroides subsp. mesenteroides and yeasts in garlic; Mucor spp., Penicillium spp., Monilia spp., Lactobacillus brevis and yeasts in both types of onions. Leuconostoc mesenteroides subsp. mesenteroides was detected in only kind of onion. In dehydrated garlic storage, Penicillium spp., Monilia spp., Lactobacillus brevis and yeasts were detected. In garlic, when a blanching step was carried out no microflora was detected. Mucor spp., Penicillium spp., Monilia spp. and Lactobacillus brevis were identified in both types of dehydrated onions. When brine immersion was included the microflora detected was significantly lower and only Penicillium spp. were found. The use of additional barriers such as blanching or brine immersion produces an important effect on the microbiological stability in these products.

Polyphasic characterization of xanthomonads isolated from onion, garlic and Welsh onion (Allium spp.) and their relatedness to different Xanthomonas species

Bacterial blight is an emerging disease that affects primarily onion, but also garlic and Welsh onion. The present study was undertaken to characterize the causative xanthomonad(s) by a polyphasic approach using a worldwide collection of 33 bacterial strains. Analysis of 16S rRNA gene sequence similarities indicated that the causal agent belongs to the campestris core in the genus Xanthomonas, which is in agreement with results of phenotypic characterization (analyses of carbon source utilization and fatty acid methyl esters). However, DNA-DNA hybridization, thermal stability of DNA reassociation and fluorescent amplified fragment length polymorphism analysis allowed the causal agent to be identified as a pathovar of Xanthomonas axonopodis.

Fresh garlic: a possible vehicle for Salmonella Virchow

A sustained increase in Salmonella enterica serovar Virchow notifications in South Eastern Australia between September 1997 and May 1998 instigated a case-control study and environmental investigations. Cases were defined as having locally acquired culture-confirmed S. Virchow phage-type 8 infection and diarrhoeal disease. Matched controls were selected by progressive digit dialling based on cases' telephone numbers. An exposure and food history questionnaire was administered by telephone. Phage typing and pulse field gel electrophoresis were performed on case and environmental isolates. Thirty-two notifications of S. Virchow infection met the case definition, 37% reported bloody diarrhoea and S. Virchow was isolated from blood in 13% of cases. Twelve patients were admitted to hospital and one died. Fresh garlic (OR 4.1, 95% CI 1.3-12.8) and semi-dried tomatoes (OR 12.6, 95% CI 1.5-103.1) were associated with these cases. The associations remained significant after adjusting for sex and age. S. Virchow (PT 8) was cultured from two brands of semi-dried tomatoes associated with cases in two different states. We provide sufficient evidence for semi-dried tomatoes and fresh garlic to be considered as potential risk foods in future Salmonella outbreak investigations.

Identification of aster yellows phytoplasma in garlic and green onion by PCR-based methods

In the summer of 1999, typical yellows-type symptoms were observed on garlic and green onion plants in a number of gardens and plots around Edmonton, Alberta, Canada. DNA was extracted from leaf tissues of evidently healthy and infected plants. DNA amplifications were conducted on these samples, using two primer pairs, R16F2n/R2 and R16(1)F1/R1, derived from phytoplasma rDNA sequences. DNA samples of aster yellows (AY), lime witches'-broom (LWB) and potato witches'-broom (PWB) phytoplasmas served as controls and were used to determine group relatedness. In a direct polymerase chain reaction (PCR) assay, DNA amplification with universal primer pair R16F2n/R2 gave the expected amplified products of 1.2 kb. Dilution (1/40) of each of the latter products were used as template and nested with specific primer pair R16(1)F1/R1. An expected PCR product of 1.1 kb was obtained from each phytoplasma-infected garlic and green onion samples, LWB and AY phytoplasmas but not from PWB phytoplasma. An aliquot from each amplification product (1.2 kb) with universal primers was subjected to PCR-based restriction fragment length polymorphism (RFLP) to identify phytoplasma isolates, using four restriction endonucleases (AluI, KpnI, MseI and RsaI). DNA amplification with specific primer pair R16(1)F1/R1 and RFLP analysis indicated the presence of AY phytoplasma in the infected garlic and green onion samples. These results suggest that AY phytoplasma in garlic and green onion samples belong to the subgroup 16Sr1-A.

The inhibitory effect of garlic (Allium sativum) on growth of some microorganisms

The aim of the present study was to compare between the anti-microbial activity of fresh garlic bulbs and that of its water extract against the potent food pathogens Staphylococcus aureus, Esherichia coil, Salmonella typhi and Bacillus cereus. Garlic segments with different concentrations (1%, 5%, and 10%) were used. Another 100 gms of garlic segments were weighed and mixed with 100 ml distilled water to prepare water extract of garlic, then 1000, 500 and 100 microg/ml were prepared. These concentrations of garlic were mixed with prepared cultures of E. coli, Staph. aureus, Bacillus cereus, and Salmonella typhi. The inhibitory effect of garlic was determined using Spectrophotometer for garlic segments and by comparing with control plates for the water extract of garlic. Results showed that the higher the garlic concentration, the higher was the microbial reduction percent. Water extract of garlic exhibited a higher microbial reduction percentage than fresh garlic.

Pseudomonas salomonii sp. nov., pathogenic on garlic, and Pseudomonas palleroniana sp. nov., isolated from rice

A total of 26 strains, including 15 strains isolated from garlic plants with the typical symptoms of 'Café au lait' disease and 11 strains isolated from diseased or healthy rice seeds and sheaths infested by Pseudomonas fuscovaginae, were compared with 70 type or reference strains of oxidase-positive pathogenic or non-pathogenic fluorescent pseudomonads. The strains were characterized by using a polyphasic taxonomic approach. Numerical taxonomy of phenotypic characteristics showed that the garlic and rice strains were related to each other. However, they clustered into separate phenons, distinct from those of the other strains tested, and were different in several nutritional tests. On the basis of DNA-DNA hybridization, the garlic and rice strains constituted two distinct DNA hybridization groups, indicating that they belonged to separate species. The two groups of strains were also well differentiated by siderotyping. Garlic strains were pathogenic to garlic plants and either weakly pathogenic or non-pathogenic on rice; rice strains were either weakly pathogenic or non-pathogenic on rice and non-pathogenic on garlic. A phylogenetic analysis of 16S rRNA gene sequences confirmed that the two groups of strains belonged to the y-Proteobacteria and to the genus Pseudomonas. The names Pseudomonas salomonii sp. nov. and Pseudomonas palleroniana sp. nov. are respectively proposed for the garlic strains and the rice strains. The type strains are P. salomonii CFBP 2022(T) ( = ICMP 14252(T) = NCPPB 4277(T)) and P. palleroniana CFBP 4389(T) (= ICMP 14253(T) = NCPPB 4278(T)).

Bulbs mycoflora and their relation with three stored product mites

The distribution of moulds on stored and field onion and garlic plants infested by bulb mites in Assiut area (Egypt) was studied using PDA medium at 28 degrees C. Among 40 host samples and the three mite species tested no significant difference was noted in the contamination by moulds. A total of 20 species appertaining to 11 genera were identified from the tested mites and their habitats. The predominant moulds on all samples were "storage moulds" from the genera Aspergillus (A. niger, A. versicolor) and Penicillium (P. chrysogenum, P. funiculosum, and "field moulds" among which Alternaria, Cladosporium, Fusarium (and its teleomorphs) and Setosphaeria were encountered most frequently. One fungus well known facultative pathogen was obtained: Beauveria bassiana. The tested mites transfer A. niger, N. haematococca, R. stolonifer and P chrysogenum outside their bodies while, A. flavus and A. ochraceus transfer through their digestive tracts along with the foods. Individuals of all mites could survived till the end of the experiment on all fungal species tested except A. niger, A. ochraceus and A. sydowii. Among 48 isolates screened for their ability to produce chitinase, about 83% of the isolates could produce this enzyme. Most of the positive isolates (17 isolates) had moderate producers

Analysis of fumonisin B(1) in Fusarium proliferatum-infected asparagus spears and garlic bulbs from Germany by liquid chromatography-electrospray ionization mass spectrometry

Fusarium proliferatum is one of a group of fungal species that produce fumonisins and is considered to be a pathogen of many economically important plants. The occurrence of fumonisin B(1) (FB(1)) in F. proliferatum-infected asparagus spears from Germany was investigated using a liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method with isotopically labeled fumonisin FB(1)-d(6) as internal standard. FB(1) was detected in 9 of the 10 samples in amounts ranging from 36.4 to 4513.7 ng/g (based on dry weight). Furthermore, the capability of producing FB(1) by the fungus in garlic bulbs was investigated. Therefore, garlic was cultured in F. proliferatum-contaminated soil, and the bulbs were screened for infection with F. proliferatum and for the occurrence of fumonisins by LC-MS. F. proliferatum was detectable in the garlic tissue, and all samples contained FB(1) (26.0-94.6 ng/g). This is the first report of the natural occurrence of FB(1) in German asparagus spears, and these findings suggest a potential for natural contamination of garlic bulbs with fumonisins.

Multiplex PCR-based detection and identification of Leuconostoc species

A multiplex polymerase chain reaction (PCR) assay has been developed for rapid and reliable identification of Leuconostoc species, by using species-specific primers targeted to the genes encoding 16S rRNA. This assay can detect and differentiate Leuconostoc species from mixed populations in natural sources as well as from pure cultures, within 3 h. This assay system consists of a total of 10 primers, two primers from each target species, and comprises two multiplex PCR reactions: one reaction for Leuconostoc carnosum, Leuconostoc citreum and Leuconostoc mesenteroides, and another reaction for Leuconostoc gelidum and Leuconostoc lactis. This multiplex PCR assay was used to identify 31 Leuconostoc strains isolated from kimchi, a fermented-cabbage product, and the results showed perfect correlation with the results of a polyphasic method, including 16S rDNA sequencing and DNA-DNA hybridization. In addition, this assay enables simultaneous detection of the above-mentioned Leuconostoc species when chromosomal DNA from these Leuconostoc species was mixed. Thus, these results suggest that this multiplex PCR is a rapid and reliable method for identification of Leuconostoc species in pure cultures or in mixed populations.

Identification and characterization of two bacteriocin-producing bacteria isolated from garlic and ginger root

Two bacteriocin-producing bacterial strains were isolated from garlic and ginger root by the agar overlay method. The bacteria were identified by 16S rRNA sequence analyses and fermentation patterns as Leuconostoc mesenteroides (garlic isolate) and Lactococcus lactis (ginger isolate). The bacteriocins were assigned the names leucocin BC2 and lactocin GI3, respectively. Physiochemical properties and antimicrobial spectra of the bacteriocins were determined by the spot-on-lawn method. Both bacteriocins were inhibited by proteolytic enzymes. Leucocin BC2 exhibited a narrow antimicrobial spectrum, inhibiting only Bacillus, Enterococcus, and Listeria species. Lactocin GI3 had a broader spectrum, inhibiting Bacillus, Clostridium, Listeria, Enterococcus, Leuconostoc, Pediococcus, and Staphylococcus species. Both bacteriocins remained active when heated at 90 degrees C for 15 min or 120 degrees C for 20 min. Leucocin BC2 assayed at 37 degrees C showed an inhibitory activity of 1,600 AU/ml, whereas at 8 degrees C the activity was 12,800 AU/ml. Conversely, lactocin GI3 activity was the same at both assay temperatures. Both bacteriocins remained active over a pH range of 2.0 to 9.0 and in various organic solvents. The activity of leucocin BC2 was increased when treated with 0.5% acetic acid and 0.5% lactic acid, whereas lactocin GI3 activity was decreased with either acid. The molecular mass values were 3.7 kDa for leucocin BC2 and 3.9 kDa for lactocin GI3. These results show that the inhibitory substances produced by the bacteria isolated from garlic and ginger are bacteriocins that appear to be different in some characteristics from previously reported bacteriocins.

Characterization of lactic acid bacteria isolated from a Thai low-salt fermented fish product and the role of garlic as substrate for fermentation

Lactic acid bacteria (LAB) isolated from raw materials (fish, rice, garlic and banana leaves) and processed som-fak (a Thai low-salt fermented fish product) were characterized by API 50-CH and other phenotypic criteria. Lactococcus lactis subsp. lactis and Leuconostoc citreum were specifically associated with fish fillet and minced fish, Lactobacillus paracasei subsp. paracasei with boiled rice and Weisella confusa with garlic mix and banana leaves. In addition, Lactobacillus plantarum, Lactobacillus pentosus and Pediococcus pentosaceus were isolated from raw materials. A succession of aciduric, homofermentative lactobacillus species, dominated by Lb. plantarum/pentosus, was found during fermentation. In total, 9% of the strains fermented starch and 19% fermented garlic, the two main carbohydrate components in som-fak. The ability to ferment garlic was paralleled by a capacity to ferment inulin. An increased percentage of garlic fermenting strains was found during fermentation of som-fak, from 8% at day 1 to 40% at day 5. No starch fermenting strains were isolated during fermentation. Three mixed LAB cultures, composed of either starch fermenting Lc. lactis subsp. lactis and Lb. paracasei subsp. paracasei, or garlic fermenting Lb. plantarum and Pd. pentosaceus, or a combination of these strains were inoculated into laboratory prepared som-fak with or without garlic. In som-fak without garlic, pH was above 4.8 after three days, irrespective of addition of mixed LAB cultures. The starch fermenting LAB were unable to ferment som-fak and sensory spoilage occurred after three days. Fermentation with the combined mix of starch and garlic fermenting strains led to production of 2.5% acid and a decrease in pH to 4.5 in two days. The fermentation was slightly slower with the garlic fermenting strains alone. This is the first report describing the role of garlic as carbohydrate source for LAB in fermented fish products.

Antimicrobial activity of a compound isolated from an oil-macerated garlic extract

A compound showing antimicrobial activity was isolated from an oil-macerated garlic extract by silica gel column chromatography and preparative TLC. On basis of the results of NMR and MS analyses, it was identified as Z-4,5,9-trithiadeca-1,6-diene-9-oxide (Z-10-devinylajoene; Z-10-DA). Z-10-DA exhibited a broad spectrum of antimicrobial activity against such microorganisms as gram-positive and gram-negative bacteria and yeasts. The antimicrobial activity of Z-10-DA was comparable to that of Z-ajoene, but was superior to that of E-ajoene. Z-10-DA and Z-ajoene are different in respect of substitution of the allyl group by the methyl group flanking a sulfinyl group. This result suggests that substitution by the methyl group would also be effective for the inhibition of microbial growth.

Novel rod-shaped viruses isolated from garlic, Allium sativum, possessing a unique genome organization

Rod-shaped flexuous viruses were partially purified from garlic plants (Allium sativum) showing typical mosaic symptoms. The genome was shown to be composed of RNA with a poly(A) tail of an estimated size of 10 kb as shown by denaturing agarose gel electrophoresis. We constructed cDNA libraries and screened four independent clones, which were designated GV-A, GV-B, GV-C and GV-D, using Northern and Southern blot hybridization. Nucleotide sequence determination of the cDNAs, two of which correspond to nearly one-third of the virus genomic RNA, shows that all of these viruses possess an identical genomic structure and that also at least four proteins are encoded in the viral cDNA, their M(r)s being estimated to be 15K, 27K, 40K and 11K. The 15K open reading frame (ORF) encodes the core-like sequence of a zinc finger protein preceded by a cluster of basic amino acid residues. The 27K ORF probably encodes the viral coat protein (CP), based on both the existence of some conserved sequences observed in many other rod-shaped or flexuous virus CPs and an overall amino acid sequence similarity to potexvirus and carlavirus CPs. The 11K ORF shows significant amino acid sequence similarities to the corresponding 12K proteins of the potexviruses and carlaviruses. On the other hand, the 40K ORF product does not resemble any other plant virus gene products reported so far. The genomic organization in the 3' region of the garlic viruses resembles, but clearly differs from, that of carlaviruses. Phylogenetic analysis based upon the amino acid sequence of the viral capsid protein also indicates that the garlic viruses have a unique and distinct domain different from those of the potexvirus and carlavirus groups. The results suggest that the garlic viruses described here belong to an unclassified and new virus group closely related to the carlaviruses.