Changes of microbial communities and metabolites in the fermentation of persimmon vinegar by bioaugmentation fermentation.

To evaluate the effects of bioaugmentation fermentation inoculated with one ester-producing strain (Wickerhamomyces anomalus ZX-1) and two strains of lactic acid bacteria (Lactobacillus plantarum CGMCC 24035 and Lactobacillus acidophilus R2) for improving the flavor of persimmon vinegar, microbial community, flavor compounds and metabolites were analyzed. The results of microbial diversity analysis showed that bioaugmentation fermentation significantly increased the abundance of Lactobacillus, Saccharomyces, Pichia and Wickerhamomyces, while the abundance of Acetobacter, Apiotrichum, Delftia, Komagataeibacter, Kregervanrija and Aspergillus significantly decreased. After bioaugmentation fermentation, the taste was softer, and the sensory irritancy of acetic acid was significantly reduced. The analysis of HS-SPME-GC-MS and untargeted metabolomics based on LC-MS/MS showed that the contents of citric acid, lactic acid, malic acid, ethyl lactate, methyl acetate, isocitrate, acetoin and 2,3-butanediol were significantly increased. By multivariate analysis, 33 differential metabolites were screened out to construct the correlation between the differential metabolites and microorganisms. Pearson correlation analysis showed that methyl acetate, ethyl lactate, betaine, aconitic acid, acetoin, 2,3-butanediol and isocitrate positively associated with Wickerhamomyces and Lactobacillus. The results confirmed that the quality of persimmon vinegar was improved by bioaugmentation fermentation.

Gaseous ozone and ozonized mist in the control of Escherichia coli on 'Rama Forte' persimmon.

This study aimed to evaluate the effectiveness of using two ozone applications (gaseous and mist) as a disinfection method for fresh persimmon. To test these sanitizers, in vitro and in vivo assays were performed, and the Escherichia coli was selected because it is a pathogen that causes foodborne diseases in humans. For in vitro experiments, a plate was inoculated with Escherichia coli strain ATCC 25922 and treated. For in vivo assays, persimmon fruit surface was inoculated with the bacteria and treated. For both assays, it was used 10,15,20,30,40 and 50 µL L-1 of gaseous ozone or ozonized mist for five minutes. The results demonstrated that the gas ozone application significantly reduced the growth of E. coli on the plate surface in vitro at doses of 30, 40 and 50 µL L-1 (with 0.83, 0.89 and 0.95 log CFU mL-1, respectively). The application of ozonized mist showed a significant reduction for 50 µL L-1 (with 1.28 log CFU g-1). And, for the in vivo assays, ozonized mist significantly reduced the number of bacteria on the persimmon surface, with a 1.57 log reduction, which was the largest for 40 µL L-1. Therefore, it is possible to conclude that the ozone application can contribute to the control of microorganisms present on fruit surfaces.

Identification and Pathogenicity of Fungal Species Associated with Branch Canker and Shoot Blight on Persimmons (Diospyros kaki) in California.

Persimmon is a relatively new crop to California agriculture. Asian persimmons (Diospyros kaki) are the dominant species commercially cultivated in the United States, primarily grown in California, covering approximately 1,153 ha of bearing trees. In the growing seasons of 2020 and 2021, unusual shoot blight and branch cankers were observed in several persimmon orchards in San Joaquin and Solano counties in California. The most prevalent symptoms were well-defined black discoloration in the cambium and streaking in the vascular tissues of green shoots. On woody branches and old pruning wounds, symptoms manifested as black wedge-shaped cankers. Isolations from affected tissues revealed the occurrence of Diaporthe species, including D. chamaeropis, D. foeniculina, and an undescribed Diaporthe sp. as the most frequent isolated pathogens, followed by Eutypella citricola and Phaeoacremonium iranianum. The isolates were identified through multilocus phylogenetic analyses using nucleotide sequences of the rDNA internal transcribed spacer, ß-tubulin, and translation elongation factor 1-alpha genes. To fulfill Koch's postulates, mycelium plugs of the various fungal species identified were inserted in 2-year-old branches of mature persimmon trees after making wounds using a corkborer in field conditions. Results showed that Diaporthe spp., E. citricola, and P. iranianum are the main causal agents of branch canker and shoot dieback of persimmon trees in California, with Diaporthe spp. being the most frequently isolated pathogen.

Inhibition of LPMOs by Fermented Persimmon Juice.

Fermented persimmon juice, Kakishibu, has traditionally been used for wood and paper protection. This protective effect stems at least partially from inhibition of microbial cellulose degrading enzymes. The inhibitory effect of Kakishibu on lytic polysaccharide monooxygenases (LPMOs) and on a cocktail of cellulose hydrolases was studied, using three different cellulosic substrates. Dose dependent inhibition of LPMO activity by a commercial Kakishibu product was assessed for the well-characterized LPMO from Thermoascus aurantiacus TaAA9A, and the inhibitory effect was confirmed on five additional microbial LPMOs. The model tannin compound, tannic acid exhibited a similar inhibitory effect on TaAA9A as Kakishibu. It was further shown that both polyethylene glycol and tannase can alleviate the inhibitory effect of Kakishibu and tannic acid, indicating a likely mechanism of inhibition caused by unspecific tannin-protein interactions.

Niastella soli sp. nov., isolated from rhizospheric soil of a persimmon tree.

A Gram-stain-negative, aerobic, motile and rod-shaped novel bacterial strain, designated MAH-29T, was isolated from rhizospheric soil of a persimmon tree. The colonies were light pink coloured, smooth, spherical and 0.1-0.8 mm in diameter when grown on Reasoner's 2A (R2A) agar for 2 days. Strain MAH-29T was able to grow at 20-37 °C, at pH 5.0-8.5 and at 0-2.0 % NaCl. Cell growth occurred on nutrient agar and R2A agar. The strain was positive in both oxidase and catalase tests. According to the 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Niastella and was closely related to Niastella vici DJ57T (97.7 % similarity), Niastella koreensis GR20-10T (97.1 %) and Niastella yeongjuensis GR20-13T (97.0 %). Strain MAH-29T has a draft genome size of 8 876 333 bp (31 contigs), annotated with 6920 protein-coding genes, 61 tRNA and four rRNA genes. The average nucleotide identity and digital DNA-DNA hybridization values between strain MAH-29T and three closely related type strains were in the range of 78.2-83.2 % and 22.1-27.0 %, respectively. The genomic DNA G+C content was 43.8 mol%. The predominant isoprenoid quinone was menaquinone 7. The major fatty acids were identified as iso-C15:0, iso-C15:1 G and iso-C17:0 3OH. On the basis of DNA-DNA hybridization results, genotypic analysis and chemotaxonomic and physiological data, strain MAH-29T represents a novel species within the genus Niastella, for which the name Niastella soli sp. nov. is proposed, with MAH-29T (=KACC 19969T=CGMCC 1.16606T) as the type strain.

Changes in the secondary compounds of persimmon leaves as a defense against circular leaf spot caused by Plurivorosphaerella nawae.

Circular leaf spot, caused by the ascomycetous fungus Plurivorosphaerella nawae (= Mycosphaerella nawae), is the most problematic fungal disease of persimmon worldwide. In Korea, persimmon exposed to P. nawae inoculum (ascospores) from May to August shows visible circular leaf spot disease symptoms from the end of August to early September. It is important to identify factors affecting this long latent period. The objective of this study was to elucidate the relation between the development of symptom of circular leaf spot and the content of phenolics compounds and vitamin C as well as the antioxidant activities in leaves. Healthy leaves (both young and old) and infected leaves of circular leaf spot-susceptible persimmon cultivar were harvested in 2016. The content of phenolics (total phenols, flavonoids, and tannins) and vitamin C, and their antioxidant activities were analyzed in all types of leaves. Compared with the asymptomatic leaves (old) and the asymptomatic parts of the infected leaves, the symptomatic parts of the infected leaves, symptomatic leaves, and asymptomatic young leaves showed significantly higher content of phenolics and vitamin C, and higher antioxidant activities. Disease incidence and severity were estimated for older leaves (emerged in early May) and younger leaves (emerged at the end of June) in 2017 and 2018. The AUDPC was higher in old leaves than younger leaves. The disease progression was much faster and severe in the older than in the younger leaves. Similar results were found in field experiments. Higher content of phenolics and antioxidant activities in the younger leaves may contribute to circular leaf spot resistance in persimmon. Furthermore, accumulation of phenolics and antioxidant activity in the infected leaves is a post-infection response and the first stage of the defense mechanism.

Komagataeibacter diospyri sp. nov., a novel species of thermotolerant bacterial nanocellulose-producing bacterium.

Thermotolerant bacterial nanocellulose-producing strains, designated MSKU 9T and MSKU 15, were isolated from persimmon and sapodilla fruits, respectively. These strains were aerobic, Gram-stain-negative, had rod-shaped cells, were non-motile and formed white-cream colonies. Phylogeny based on the 16S rRNA gene sequences revealed that MSKU 9T and MSKU 15 represented members of the genus Komagataeibacter and formed a monophyletic branch with K. swingsii JCM 17123T and K. europaeus DSM 6160T. The genomic analysis revealed that overall genomic relatedness index values of MSKU 9T with K. swingsii JCM 17123T and K. europaeus DSM 6160T were ~90 % average nucleotide identity (ANI) and ≤58.2 % digital DNA-DNA hybridization (dDDH), respectively. MSKU 9T and MSKU 15 can be differentiated from the closely related K. swingsii JCM 17123T by their growth on 30 % d-glucose and ability to utilize and to form acid from raffinose and sucrose as carbon sources, and from K. europaeus DSM 6160T by their ability to grow without acetic acid. The genomic DNA G+C contents of MSKU 9T and MSKU 15 were 60.4 and 60.2 mol%, respectively. The major fatty acids of MSKU 9T and MSKU 15 were summed feature 8 (C18 : 1 ω7c and/or C18  : 1ω6c). The respiratory quinone was determined to be Q10. On the basis of the results of the polyphasic taxonomic analysis, MSKU 9T (=TBRC 9844T=NBRC 113802T) represents a novel species of the genus Komagataeibacter, for which the name Komagataeibacter diospyri sp. nov. is proposed.

Cellulosic Nanomaterial Production Via Fermentation by Komagataeibacter sp. SFCB22-18 Isolated from Ripened Persimmons.

Bacterial nanocellulose (BNC) which is generally synthesized by several species of bacteria has a wide variety of industrial uses, particularly in the food and material industries. However, the low levels of BNC production during the fermentation process should be overcome to reduce its production cost. Therefore, in this study, we screened and identified a new cellulose-producing bacterium, optimized production of the cellulose, and investigated the morphological properties of the cellulosic materials. Out of 147 bacterial isolates from ripened fruits and traditional vinegars, strain SFCB22-18 showed the highest capacity for BNC production and was identified as Komagataeibacter sp. based on 16S rRNA sequence analysis. During 6-week fermentation of the strain using an optimized medium containing 3.0% glucose, 2.5% yeast extract, 0.24% acetic acid, 0.27% Na2HPO4, and 0.5% ethanol at 30°C, about 5 g/l of cellulosic material was produced. Both imaging and IR analysis proved that the produced cellulose would be nanoscale bacterial cellulose.

Anti-Aging Activity of Lavandula angustifolia Extract Fermented with Pediococcus pentosaceus DK1 Isolated from Diospyros kaki Fruit in UVB-Irradiated Human Skin Fibroblasts and Analysis of Principal Components.

The effects of Lavandula angustifolia extract fermented with Pediococcus pentosaceus DK1 on UVB-mediated MMP-1 expression and collagen decrease in human skin fibroblasts were determined, and the conversion of its components was also analyzed. Fermentation was performed at varying L. angustifolia extract and MRS medium concentrations, and optimal fermentation conditions were selected. L. angustifolia extracts showed decreased cytotoxicity after fermentation in the fibroblasts. UVB-irradiated fibroblasts treated with fermented L. angustifolia extract showed MMP-1 expression 8.2-14.0% lower than that in UVB-irradiated fibroblasts treated with non-fermented extract. This was observed even at fermented extract concentrations lower than those of non-fermented extracts. Fibroblasts treated with fermented L. angustifolia extract showed 20% less reduction in collagen production upon UVB irradiation than those treated with non-fermented extracts. UVB-irradiated fibroblasts treated with fermented L. angustifolia extracts showed 50% higher inhibition of ROS generation than those treated with non-fermented extract. Luteolin and apigenin glycosides of L. angustifolia were converted during fermentation, and identified using RP-HPLC and LC/ESI-MS. Therefore, the effects of L. angustifolia extract on MMP-1 expression and collagen decrease in UVB-irradiated human skin fibroblasts were increased through fermentation by P. pentosaceus.

Development of air-blast dried non-Saccharomyces yeast starter for improving quality of Korean persimmon wine and apple cider.

A total of 512 yeasts, including 422 non-Saccharomyces yeasts, were isolated from various fruits including apple, aronia, Muscat Bailey A grapes, and persimmon. These were used to prepare persimmon wine and apple cider starters that produced high levels of aromatic compounds, which contribute to high-quality fermented products. Environmental tolerance testing with 20% glucose and 8% EtOH, alongside a sniffing test, led to the selection of Wickerhamomyces anomalus (Synonym Pichia anomala) SJ20, Meyerozyma caribbica (Synonym Pichia caribbica) YP1, Pichia kluyveri CD34, Hanseniaspora uvarum SJ69 (for persimmon wine), W. anomalus CS7-16 (for apple cider), and Starmerella bacillaris (Synonym Candida zemplinina) CD80 (for both wines) as wine starters. These strains had high environmental stress tolerance and the highest sniffing test scores. Persimmon wine and apple cider were fermented using these strains in single- or mixed-culture with S. cerevisiae W-3 to determine the improved effect on wine aroma. In accordance with the results of volatile ester compounds and sensory evaluation, W. anomalus SJ20, H. uvarum SJ69, and W. anomalus CS7-16 had an excellent potential as persimmon wine and apple cider starters. Moreover, other strains also showed a good potential for a distinctive persimmon wine and apple cider because of the different compositions of the various volatile ester compounds. Six types of sugars (fructose, glucose, maltose, sucrose, raffinose, sucrose, and trehalose), four types of rehydration solutions (distilled water, 1× phosphate buffered saline, 0.85% NaCl, and 1% peptone water), and two types of antioxidants (l-ascorbic acid and glutathione) were examined to improve the survival rate of air-blast dried non-Saccharomyces yeast cells. Optimal sugar and rehydration conditions for each strain were validated, and scanning electron microscopy showed that each cell was surrounded by protectants, including sugar, skim milk, and lactomil. Storability assessment of air-blast dried yeast cells maintained at 4 °C for two months indicated that at least one condition in each strain had a higher survival rate than the control, regardless of the concentration or type of antioxidant treatment, except for M. caribbica YP1. These results suggest that antioxidant treatment contributes to maintaining the viability of air-blast dried cells in hostile environments.

Phylogenetic and Morphological Reassessment of Mycosphaerella nawae, the Causal Agent of Circular Leaf Spot in Persimmon.

Persimmon (Diospyros kaki) fruit production is severely affected by circular leaf spot worldwide. Mycosphaerella nawae causes circular leaf spot of persimmon (CLSP) and can result in leaf spot, defoliation, early fruit maturation, and subsequent softening and abscission. The morphology and phylogenetic position of M. nawae within the family Mycosphaerellaceae is, therefore, of utmost importance given its impact on persimmon production. Based on previous morphological and molecular studies, the phylogenetic position of the anamorphic genera associated with M. nawae remain in confusion. In the present study, 15 isolates of M. nawae were collected from the tissue of living leaves exhibiting leaf spot symptoms. A subsample of three isolates was characterized phylogenetically and morphologically. Isolates were compared based on DNA sequence data for the internal transcribed spacer region (ITS1-5.8S ITS2), part of the 28S nrDNA including domains D1-D3 (LSU), actin (Act), translation elongation factor 1-alpha (EF-1α), and RNA polymerase II second largest subunit (rpb2). The anamorph and teleomorph structures, ascospore germination patterns, as well as host specificity were used to describe the isolates. The phylogenetic and morphological analyses revealed that M. nawae requires a new holomorphic genus within Mycosphaerellaceae, described herein as Plurivorosphaerella gen. nov. A host specificity test revealed that Plurivorosphaerella nawae comb. nov. (M. nawae) can superficially colonize, but not infect, apple, peach, cherry, and plum.

Molecular and Morphological Characterization of Colletotrichum Species in the Colletotrichum gloeosporioides Complex Associated with Persimmon Anthracnose in South Korea.

Anthracnose is a major disease of persimmon in the pre- and postharvest phase. Several species of Colletotrichum (Colletotrichum gloeosporioides, C. acutatum, and C. horii) have been reported as causal agents of persimmon anthracnose in South Korea. In this study, a collection of 50 isolates associated with persimmon anthracnose were collected from Sangju (n = 25) and Cheongdo-gun (n = 25), South Korea. The morphological characteristics of all 50 Colletotrichum isolates were similar, and it was difficult to identify the isolates to the species level. A subsample of eight isolates was characterized phylogenetically to ascertain species. BLAST search and phylogenetic analysis of the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and actin (ACT) genes revealed two species: C. horii as well as a previously unreported persimmon anthracnose causal agent C. siamense. C. siamense isolates were confirmed again by phylogenetic analysis of the ITS, ACT, GAPDH, calmodulin, and Apn2-Mat1-2 intergenic spacer partial mating type genes. Koch's postulates for C. horii and C. siamense were fulfilled, confirming the pathogenicity of the two species in persimmon fruit. Morphological characteristics (colony morphology and size and shape of conidia and appressoria) from two representative isolates support results of the phylogenetic analysis and match those of previous descriptions of C. horii and C. siamense.

Leucocin C-607, a Novel Bacteriocin from the Multiple-Bacteriocin-Producing Leuconostoc pseudomesenteroides 607 Isolated from Persimmon.

Leuconostoc pseudomesenteroides 607, isolated from persimmon fruit, was found to have high inhibitory activity against Listeria monocytogenes and several other Gram-positive bacteria. Inhibitory substances were purified from culture supernatant by ion-exchange chromatography, Sep-Pak C18 cartridge, and reverse-phase high-performance liquid chromatography (RP-HPLC). Two antibacterial peptides were observed during the purification procedures. One of these peptides had a molecular size of 4623.05 Da and a partial N-terminal amino acid sequence of NH2-KNYGNGVHxTKKGxS, in which the YGNGV motif is specific for class IIa bacteriocins. A BLAST search revealed that this bacteriocin was similar to leucocin C from Leuconostoc mesenteroides. Leucocin C-specific primers were designed and a single PCR product was amplified. Analysis of the nucleotide sequence has revealed a putative peptide differing by only one amino acid residue from the sequence of leucocin C. No identical peptide or protein has been reported in the literature, and this peptide, termed leucocin C-607, was therefore considered to be a new variant of leucocin C produced by Leuc. pseudomesenteroides 607. Another antibacterial peptide purified from the same culture supernatant had a molecular size of 3007.7 or 3121.97 Da. However, detailed information regarding this second peptide remains to be determined. Distinct characteristics, such as heat stability and inhibitory spectrum, were observed for the two bacteriocins produced by Leuc. pseudomesenteroides 607. These results suggested that Leuc. pseudomesenteroides 607 produces leucocin C-607 along with another unknown bacteriocin.

Integration of antimicrobial pectin-based edible coating and active modified atmosphere packaging to preserve the quality and microbial safety of fresh-cut persimmon (Diospyros kaki Thunb. cv. Rojo Brillante).

BACKGROUND: The greatest hurdle to the commercial marketing of fresh-cut fruits is related to their higher susceptibility to enzymatic browning, tissue softening, and microbial growth. The aim of this study was to test the efficacy of a pectin-based edible coating and low oxygen modified atmosphere packaging (MAP) to control enzymatic browning and reduce microbial growth of fresh-cut 'Rojo Brillante' persimmon. The survival of Escherichia coli, Salmonella enteritidis and Listeria monocytogenes artificially inoculated on fresh-cut fruit was also assessed. The pectin coating was amended with 500 IU mL-1 nisin (NI) as antimicrobial agent and 10 g kg-1 citric acid and 10 g kg-1 calcium chloride as anti-browning and firming agents, respectively. Persimmon slices were dipped in the coating or in water (control) and packed under 5 kPa O2 (MAP) or in ambient atmosphere for up to 9 days at 5 °C. Microbial growth, package gas composition, colour, firmness, polyphenol oxidase activity, visual quality and overall sensory flavour of persimmon slices were measured during storage. RESULTS: Coating application combined with active MAP significantly reduced the CO2 emission and O2 consumption in the package. The coating was effective in reducing browning and also inhibited the growth of mesophilic aerobic bacteria. Coating also reduced the populations of E. coli, S. enteritidis and L. monocytogenes. CONCLUSION: The combination of the pectin-based edible coating and active MAP proved to be the most effective treatment to maintain the sensory and microbiological quality of persimmon slices for more than 9 days of storage. © 2016 Society of Chemical Industry.

Co-production of tannase and pectinase by free and immobilized cells of the yeast Rhodotorula glutinis MP-10 isolated from tannin-rich persimmon (Diospyros kaki L.) fruits.

Hyper tannase and pectinase-producing yeast Rhodotorula glutinis MP-10 was isolated from persimmon (Diospyros kaki L.) fruits. The main pectinase activity of yeast was exo-polygalacturonase. No pectin methyl esterase and too low pectin lyase activities were detected for this yeast. The maximum exo-activities of tannase and polygalacturonase were determined as 15.2 and 26.9 U/mL for free cells and 19.8 and 28.6 U/mL for immobilized cells, respectively. Immobilized cells could be reused in 13 successive reaction cycles without any loss in the maximum tannase and polygalacturonase activities. Besides, too little decreases in activities of these enzymes were recorded between 14 and 18 cycles. At the end of 18 successive reaction cycles, total 503.1 U/mL of polygalacturonase and 349.6 U/mL of tannase could be produced using the same immobilized cells. This is the first report on the use of free and/or immobilized cells of a microorganism for the co-production of tannase and pectinase.

Identification of yeast and acetic acid bacteria isolated from the fermentation and acetification of persimmon (Diospyros kaki).

Persimmon (Diospyros kaki) is a seasonal fruit with important health benefits. In this study, persimmon use in wine and condiment production was investigated using molecular methods to identify the yeast and acetic acid bacteria (AAB) isolated from the alcoholic fermentation and acetification of the fruit. Alcoholic fermentation was allowed to occur either spontaneously, or by inoculation with a commercial Saccharomyces cerevisiae wine strain, while acetification was always spontaneous; all these processes were performed in triplicates. Non-Saccharomyces yeast species were particularly abundant during the initial and mid-alcoholic fermentation stages, but S. cerevisiae became dominant toward the end of these processes. During spontaneous fermentation, S. cerevisiae Sc1 was the predominant strain isolated throughout, while the commercial strain of S. cerevisiae was the most common strain isolated from the inoculated fermentations. The main non-Saccharomyces strains isolated included Pichia guilliermondii, Hanseniaspora uvarum, Zygosaccharomyces florentinus and Cryptococcus sp. A distinct succession of AAB was observed during the acetification process. Acetobacter malorun was abundant during the initial and mid-stages, while Gluconacetobacter saccharivorans was the main species during the final stages of these acetifications. Four additional AAB species, Acetobacter pasteurianus, Acetobacter syzygii, Gluconacetobacter intermedius and Gluconacetobacter europaeus, were also detected. We observed 28 different AAB genotypes, though only 6 of these were present in high numbers (between 25%-60%), resulting in a high biodiversity index.

Estimation of leaf wetness duration requirements of foliar fungal pathogens with uncertain data-an application to Mycosphaerella nawae.

Wetness of the host surface is a critical environmental factor for the development of foliar fungal diseases, but it is difficult to estimate the wetness durations required by pathogens for infection when only few experimental data are available. In this paper, we propose a method to estimate wetness duration requirements of foliar fungal pathogens when precise experimental data are not available. The proposed method is based on approximate Bayesian computation. It only requires lower and upper bounds of wetness duration requirements for one or fewer temperatures. We describe the method, show how to apply it to an infection model, and then present a case study on Mycosphaerella nawae, the causal agent of circular leaf spot of persimmon. In this example, the parameters of a simple infection model were estimated using experimental data found in the literature for the pathogen, and the model was applied to assess the risk in a Spanish area recently affected by the disease. The results showed that the probability of successful infection was higher than 0.5 for 32% of the on-site wetness durations recorded in the affected area. Results obtained with simulated data showed that our method was able to improve the estimation of wetness duration requirement. Given the flexibility of the proposed method, we expect it to become adopted for assessing the risk of introduction of exotic fungal plant pathogens.

Growth and survival of invasive Aedes albopictus larvae on Diospyros virginiana leaves.

Studies on the interactions of exotic species with their invaded environment are imperative in understanding their invasion biology. Larvae of container mosquitoes such as the invasive Aedes albopictus (Skuse) feed on microorganisms that subsist on allochthonous inputs like leaves. Ae. albopictus are vectors for many diseases including West Nile virus and are rapidly expanding their distribution in the United States. We tested the larval performance ofAe. albopictus at different larval densities in maple, oak, American elm, and persimmon. Survival was significantly lower and days to pupation were significantly higher with persimmon leaves compared with all others. In a follow-up experiment, we compared the performance of Ae. albopictus in different amounts of oak and persimmon and different ratios of persimmon + oak. The linear model for the growth rate (defined by larval head width) showed a positive slope as the amount of oak leaves increased in oak treatment, but there was no significant slope for persimmon. In the persimmon + oak combination, as the ratio of persimmon to oak increased, the growth rates of the larvae decreased. Lack of a significant slope for survival rate in combination with the results from the growth rate indicated that persimmon was a poor nutritional resource for Ae. albopictus.

Incidence and growth of Listeria monocytogenes in persimmon (Diospyros kaki) fruit.

The incidence of Listeria monocytogenes on persimmon (Diospyros kaki) surface of 'Fuyu' and 'Rama Forte' was evaluated during a 5-month-period (from March to July) of two seasons periods (years 2005 and 2006). The fruits were collected in wholesale and street markets and retail in Sao Paulo and Campinas City, Brazil. A total of 582 fruits were analyzed using the Bax System which is based on the Polymerase Chain Reaction. The ability of this pathogen to grow on the peel and pulp of the two persimmon varieties was also verified at different incubation periods at the temperatures of 10, 20 and 30 degrees C. The growth parameters were obtained by modeling the experimental data using the Gompertz function. The incidence survey showed the absence of L. monocytogenes. The growth curves showed that L. monocytogenes can grow on the peel as well as in the pulp of the two persimmon varieties studied incubated at 10, 20 and 30 degrees C and that low temperatures can reduce the generation rate but does not inhibit its growth.

On-farm sources of microbial contamination of persimmon fruit in Japan.

Potential sources of microbial contamination for persimmon fruit during growing and harvesting in the 2005 season were investigated to provide a baseline to design the good agricultural practices program for persimmons in Japan. Microbial counts in the peel of persimmon fruit during production season were close to or below 2.4 log CFU/g for bacteria and 3.0 log CFU/g for fungi but were above these values on harvested fruit. The counts in the flesh were below the detection level with all fruit. Bacteria and molds isolated from peel and flesh of persimmons during growing were phytopathogenic and soilborne organisms such as bacteria genera Enterobacter and Bacillus and mold genera Fusarium and Cladosporium, which were found in soil, weeds, agricultural water, and pesticide solution throughout the production season. The agricultural water was one of the most important potential preharvest sources, because Escherichia coli O157:H7 was identified from agricultural water in May, and Salmonella was detected in agricultural water, pesticide solution containing the agricultural water for the mixture, and soil after application of the pesticide solution in June. Neither of the two pathogenic bacteria was detected in any of the fruit samples. Microbial counts and diversity in the peel of persimmons at harvest increased after contact with plastic harvest basket and container, which could be sources of contamination during harvesting. Therefore, monitoring and management on-farm should focus on agricultural water and harvest equipment as important control points to reduce microbial contamination on persimmons.