Tomato Samples Research Articles

Bacteriological Analysis of Contamination Level of Selected Vegetables Sold in Some Markets in Niamey, Niger

Vegetables are an important food source of nutrients, vitamins and dietary fiber, and therefore play a vital role in human health and well-being. Unfortunately, they are perishable products that could be vectors for the transmission of infectious diseases. The aim of this study was to analyses the level of bacteriological contamination of the samples of tomatoes (29), carrots (12), lettuces (47) and onions (12) sold in five (5) markets of community urban of Niamey. To this end, contamination indicator germs such as Total Aerobic Mesophilic Flora (TAMF), Total Coliforms (TC), Faecal Coliforms (FC), Enterobacteria (Ent), Faecal Streptococci (FS), Clostridium perfringens (CP) and Escherichia coli (E. coli) were enumerated, using methods specific to each germ. Analysis of the results showed tomatoes to be highly contaminated with FS, CP and E. coli (9.75±1.81.105; 1.33±2.30.105 and 2.25±2.48.105 CFU/g respectively), carrots with TAMF, FC, Ent (1.37±1.24.107; 4.48±0.34.106; 7.44±0.34.106 CFU/g respectively) and onions with TC (4.45±0.84.106 CFU/g). The sanitary quality of these vegetables is low. Hence the need for strict compliance with good hygiene practices in markets to ensure a healthy vegetable.

Electronic nose for detecting Colletotrichum coccodes causing anthracnose fruit rots in tomatoes

Electronic nose (EN) technology has several applications targeting various study areas, and food spoilage is one of these sections. This study investigated the ability of the EN, with metal-oxide sensors (MOS), to sense the presence of Colletotrichum coccodes, which cause anthracnose fruit rots, on tomato fruit and to distinguish between different stages and doses of infection. C. coccodes were identified by an appropriate polymerase chain reaction (PCR) program and sequencing, using two different primer sets: ITS1F/ITS4 and Cc1F1/Cc2R1. Three intact homogeneous tomato samples were injected with three different concentrations of conidial fungal suspension: 3 × 104, 3 × 105 and 3 × 106 conidia/ml, and three others were kept as negative controls. Principal component analysis (PCA) was used in analyzing the data acquired from the EN sensors. The results of PCA showed that EN was able to detect the presence of C. coccodes pathogen at early stages (two days of infection and before any symptoms appear). Moreover, EN was able to differentiate between different infection stages. In addition, the concentrations of infected samples on the sixth, eighth and tenth days were clearly differentiated. The use of EN is a promising technique for determining quality assurance and control.

Microbiological quality of irrigation water on highly diverse fresh produce smallholder farms: elucidating environmental routes of contamination.

To evaluate the microbiological safety, potential multidrug-resistant bacterial presence and genetic relatedness (DNA fingerprints) of Escherichia coli isolated from the water-soil-plant nexus on highly diverse fresh produce smallholder farms. Irrigation water (n=44), soil (n=85), and fresh produce (n=95) samples from six smallholder farms with different production systems were analysed for hygiene indicator bacterial counts and the presence of shigatoxigenic E. coli and Salmonella spp. using standard microbiological methods. Identities of isolates were confirmed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the genetic relatedness of the E. coli isolates determined using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) analysis. Irrigation water E. coli levels ranged between 0 and 3.45 log MPN/100 ml-1 with five farms having acceptable levels according to the World Health Organization limit (3 log MPN/100 ml-1). Fresh produce samples on four farms (n=65) harboured E. coli at low levels (<1 log CFU/g-1) except for one sample from kale, spring onion, green pepper, onion, and two tomato samples, which exceeded international acceptable limits (100 CFU/g-1). Only one baby carrot fresh produce sample tested positive for Salmonella spp. Of the 224 samples, E. coli isolates were identified in 40% (n=90) of all water, soil, and fresh produce types after enrichment. Additionally, the DNA fingerprints of E. coli isolates from the water-soil-plant nexus of each respective farm clustered together at high similarity values (>90%), with all phenotypically characterized as multidrug-resistant. The clustering of E. coli isolated throughout the water-soil-plant nexus, implicated irrigation water in fresh produce contamination. Highlighting the importance of complying with irrigation water microbiological quality guidelines to limit the spread of potential foodborne pathogens throughout the fresh produce supply chain.

Management of seed borne ralstonia solanacearum in brinjal (Solanum melongena L.) and tomato (Lycopersicon esculentum Mill.)

Total of 165 bacterial isolates of Ralstonia solanacearum were collected from different seed samples of tomato and brinjal in various seed sources and 22 isolates were tested to find out the management tools among different management approaches. Hundred percent reduction of bacterial incidence was found with Gentamicin (0.1, 0.05%), Erythromycin (0.1, 0.05%) and Doxycycline (0.1%) over control in both brinjal and tomato treated seeds in nutrient agar medium. Seed treatment with BAU-Biofungicide (3%) exhibited 83.61% decreases of bacterial incidence over control in tomato and 90.28% reduction in brinjal seeds. Garlic also showed better performance in controlling R. solanacearum among the plant extracts. Antibiotic sensitivity test revealed that maximum number of isolates of R. solanacearum was found to be sensitive to Gentamicin and Erythromycin, and the highest number of isolate of R. solanacearum of tomato and brinjal seeds marked resistant to Doxycycline. Higher germination 40.38% was achieved over control in tomato seed and 26.67% germination was in brinjal seed when the seeds were treated with BAU-Biofungicide (3%). Among all the treatments, BAU-Biofungicide (3%) also resulted in the highest increase of vigor index (77.36%) in tomato and brinjal seed with an increase of 69.91% over untreated control. Bangladesh J. Bot. 53(1): 173-183, 2024 (March)

Chemical bonding of cross-linked glutaraldehyde/chitosan on the surface of a titanium wire to prepare a robust biocompatible SPME fiber for analysis of phytohormones in plants

A robust biocompatible solid-phase microextraction (SPME) fiber, so-called Ti/APTS/GA/CS, was prepared by chemical bonding of cross-linked glutaraldehyde-chitosan to the surface of a titanium wire using APTS. The fiber was applied for sampling of phytohormones in plant tissues, followed by HPLC-UV analysis. The structure and morphology of the fiber coating was investigated by FT-IR, SEM, EDX, XRD, and TGA techniques. A Box-Behnken design was implemented to optimize the experimental variables. The calibration graphs were linear over a wide linear range (0.5–200 μg L−1) with LODs over the range of 0.01–0.06 μg L−1. The intra-day and inter-day precisions were found to be 1.3–6.3% and 4.3–7.3%, respectively. The matrix effect values ranged from 86.5% to 111.7%, indicating that the complex sample matrices had an insignificant effect on the determination of phytohormones. The fiber was successfully employed for the direct-immersion SPME (DI-SPME-HPLC) analysis of the phytohormones in cucumber, tomato, date palm, and calendula samples.

Association of Plant-Parasitic Nematodes and Soil Physicochemical Properties in Tomatoes in Turfloop, Limpopo Province, South Africa

Turfloop constitutes an area in Mankweng, situated in the Limpopo Province of South Africa, where several villages are home to smallholder farmers who specialize in vegetable farming. Among the most crucial crops cultivated in this region is tomato, a fruit that has gained significant commercial importance due to its high demand and versatility in various culinary applications. To determine the relationship of plant-parasitic nematodes and soil physicochemical properties, soil samples were collected from tomato fields. Overall, our results showed that seven nematode genera were in the tomato fields. There was a significant positive correlation between the number of Meloidogyne and potassium (r = 0.903) and a negative correlation with Na (r = −0.684). In contrast, there was no association between the number of Meloidogyne spp. and the pH and texture of the fields. The number of Criconema in the field was negatively correlated with pH (r = −0.732). Soil texture percentages, including clay (r = 0.744), sand (r = −0.744), and silt (r = 0.706), were only correlated with the number of Criconema. The number of dagger nematodes, Xiphinema, was only correlated negatively with NH4+ (r = −0.589) and positively with boron (B) (r = 0.779). None of the soil variables were correlated with the number of Pratylenchus. The principal component analysis (PCA) placed soil samples of tomatoes together, in which the number of Meloidogyne was not correlated to any soil sample site. In conclusion, plant-parasitic nematodes that were associated with tomatoes are of high economic importance as they can reduce the yield. Criconema was found to be sensitive to the soil’s physicochemical properties. In addition, Helicotylenchus was found in all soil samples. Our results suggest that the plant-parasitic nematodes in tomatoes have high diversity with the potential to reduce crop production.

Assessment of Potential Human Health Risk Associated With Heavy Metals in Soil – Vegetables System Irrigated by Rift Valley Lake Ziway, Ethiopia

Metal contamination of vegetables is a major concern, especially in areas where irrigation has been used for a long time. The Central Ethiopian Rift Valley Region is highly affected due to the heavy use of agrochemicals throughout the year. Although some studies have been conducted on the concentration and level of heavy metal pollution, little attention has been paid to their impact on human health. This study determined the concentrations of nine metals (As, Cd, Cr, Co, Cu, Hg, Ni, Pb, and Zn) in a soils and vegetables (tomatoes and onions) irrigated by Lake Ziway, Ethiopia. An inductively coupled plasma optical emission spectrometer (ICP-OES) was used to determine the heavy metal levels. Moreover, the study evaluated the health risks associated with consuming contaminated vegetables by employing major indices, including non-carcinogenic and carcinogenic risks. The results showed that the mean concentrations of Pb, As, Hg, and Cr in all tomato and onion samples and the average Zn, Pb, Cd, and Hg levels in all soil samples exceeded the FAO/WHO threshold. Non-carcinogenic health risk estimates showed that As, Pb, Hg, and Co for children and Pb and Co for adults had THQ values greater than 1, indicating the possibility of systemic health risks. Carcinogenic health risk showed that Ni posed a risk of developing cancer for both adults and children, with values ranging from 10−3 to 10−1. In addition, children are likely to have a higher cancer risk due to exposure to As and Cr. Therefore, it is crucial to raise awareness among stakeholders and implement effective monitoring policies to safeguard public health both within and beyond the study area.

Study and Evaluation of Morpho-Anatomical Characteristics of the Leaves of Tomato Plant Varieties and Hybrids

This article has been investigated and evaluated by studying the specification of anatomical structure of the sort samples of tomatoes. Studies have shown that anatomical indicators mainly have a great importance in learning of drought resistance, determining the origins of the different varieties, choosing of hybrid plants in selection work of the size and number of stomata, and total thickness of the leaves. Studying of anatomical characters of tomato sort samples and hybrids plants has shown that learning of the total thickness of the leaf and the size of number of stomata has a certain importance in selection of hybrid plants. It is defined that in sort samples which their cuticle layer is thick, water evaporation decreases, and they become resistible to illness. So, the sample of Volgograd 5/95, 82 and 90 in upper epidermis and the sample of 93 in lower epidermis were differed for the thickness of cuticle layer. As results of studies, it has been identified that chlorenchyma present in the sort samples predominant for differing according to the total thickness of the leaf. Moreover, studying of the leaf cells has shown that the evaporation of water is higher in the leaves which the number of stomatas is more, and the epidermis cells are few, for that reason, the leaves of Solanum pimpinellifolium L. (wild form) are in thin needle shaped in order to reduce the transpiration. Exactly for this reason, it’s recommended to use the wild form as a donor in conducting the future selection work.

Species-Dependent Impacts on the Nutritional Profile of Tomato (Solanum lycopersicum L.) and Rocket (Eruca sativa L.) Plants Following to Foliar Application of Yeast Suspensions

The foliar application of yeast (Saccharomyces cerevisiae) suspensions is a widely used small-scale horticultural practice against stress impacts and to boost vegetative and nutritional characteristics. In this study, the impact of two strains of S. cerevisiae was investigated on tomato (Solanum lycopersicum L.) and rocket (Eruca sativa L.) plants in terms of vegetative growth and nutritional content, focusing on antioxidant properties (FRAP, DPPH, TPC, lycopene) and chlorophyll content. The treatments were applied in two dilutions (0.1 and 1% v/v) and two frequencies (once and three times). When the type strain solutions were applied, DPPH values of both tomato and rocket samples were elevated up to 7.18 and 17.98 i%, respectively, compared to control values of 6.26 and 14.11 i%, respectively. While the other investigated antioxidant traits (FRAP, TPC, lycopene) were identical or slightly lower, than the control values, total chlorophyll content was significantly increased for tomato, up to 61.18 g/100 g, from the control value of 53.46 g/100 g, and for rocket, reaching 43.14 g/100 g, from the control value of 39.13 g/100 g, after using instant yeast solutions. Among the combinations, the double-sprayed 1% suspension and the single-sprayed 0.1% suspension had the most favorable impact on the investigated nutritional traits. Species-level application technology details are still open for refinements.

Rapid and sensitive quantitation of amitraz in orange, tomato, and eggplant samples using immunochromatographic assay

Amitraz (AMT) is a broad-spectrum formamidine insecticide and acaricide. In this study, we produced an anti-AMT monoclonal antibody (mAb) with high performance. The half-maximal inhibitory concentration of the anti-AMT mAb was 4.418 ng/mL, the cross reactivity with other insecticides was negligible, and an affinity constant was 2.06 × 109 mmol/L. Additionally, we developed an immunochromatographic assay for the rapid detection of AMT residues in oranges, tomatoes, and eggplants. The cut-off values were 2000 μg/kg in oranges and tomato samples and 1000 μg/kg in eggplant samples and the calculated limits of detection were 14.521 μg/kg, 6.281 μg/kg, and 3.518 μg/kg in oranges, tomatoes, and eggplants, respectively, meeting the detection requirements for AMT in fruits and vegetables. The recovery rates ranged between 95.8 % and 105.2 %, consistent with the recovery rates obtained via LC-MS/MS. Our developed immunochromatographic assay can effectively, accurately, and rapidly determine AMT residues in oranges, tomatoes, and eggplants.

Isolation, identification, and pathogenicity of Rhizoctonia spp. recovered from soil samples of the greenhouse tomato growing area of the West Mediterranean region, Türkiye

AbstractThis study's objective was to identify the anastomosis groups and pathogenicity of Rhizoctonia species from soil samples in tomato production areas of Antalya, Burdur, and Isparta provinces in the West Mediterranean Region of Türkiye during the 2022 season. Soil samples were gathered from tomato plant rhizospheres in 223 different greenhouses, and isolations were done from the soil using the baiting technique. According to the results of morphological characterization and sequence analysis of the internal transcribed spacers of the ribosomal DNA, 47 Rhizoctonia isolates were defined as binucleate and 21 isolates as multinucleate. The collection of binucleate Rhizoctonia (Ceratobasidium sp.) isolates included representatives of Anastomosis Group‐F (61.76%), AG‐A (1.47%), and an unidentified binucleate Rhizoctonia (Ceratobasidium sp.) (5.88%). Multinucleate R. solani included AG 4 HG‐I (26.47%) and AG 4 HG‐II (4.41%). Pathogenicity tests showed statistically significant differences in virulence between binucleate Rhizoctonia (Ceratobasidium sp.) isolates and multinucleate Rhizoctonia isolates. All R. solani AG 4 HG‐II isolates and most of the AG 4 HG‐I isolates were pathogenic, causing severe necrosis symptoms and damping off in tomato seedlings, but binucleate AG‐A and AG‐F isolates were nonpathogenic. This study is the first detailed report about Rhizoctonia species isolated from the soil of tomato plants grown in greenhouse production areas in Türkiye.

Draft genome sequence of antibiotic-resistant Shigella flexneri MTR_GR_V146 strain isolated from a tomato (Solanum lycopersicum) sample collected from a peri-urban area of Bangladesh.

This study announces the genome sequence of the Shigella flexneri MTR_GR_V146 strain isolated from a tomato (Solanum lycopersicum) sample in Bangladesh. This strain has a 4,624,521 bp genome length (coverage: 73.07×), 2 CRISPR arrays, 1 plasmid, 52 predicted antibiotic resistance genes, and 53 virulence factor genes.

Dispersive Micro‐Solid Phase Extraction of Selected Metals in Water and Food Samples Followed by ICP‐OES Analysis: Method Development, Analysis of Real Samples and Greenness Evaluation

AbstractMultiwalled carbon nanotubes (MWCNTs) are well‐known adsorbents because of their high surface area, layered and hollow architecture, hydrophobicity, and multiple and easily accessible adsorption sites. In this study, MWCNTs were used for dispersive micro‐solid‐phase extraction of various metal chelates in environmental and food samples. Different parameters such as concentration of the chelating reagent, the sorbent dosage, the extraction time, the desorption time, and the strength of the eluent were suitably optimized. Under the optimum extraction conditions, the proposed method demonstrated a good linear working range for all the analytes, with correlation coefficients above 0.9915. The limit of detection ranged from 0.02 to 0.21 μg/L. The inter‐day and intra‐day relative standard deviations were less than 2.5 %. The proposed method was used for the determination of selected metals in tap water, drinking water, cucumber, and tomato samples. In the end, GAPI tool was used to evaluate the greenness of the method.

A vortex-assisted liquid-liquid extraction followed by dispersive-solid phase extraction (VA-LLE/d-SPE) for the determination of eight benzoylphenylureas insecticides in tomatoes and cucumbers

AbstractMonitoring benzoylphenylureas (BPUs) residues in ready-to-eat vegetables is of great interest for an adequate assessment of human pesticide exposure. A rapid, inexpensive, simple, and effective method for determining 8 BPUs insecticides in tomatoes and cucumbers was developed and validated. Vortex-assisted liquid-liquid extraction (VA-LLE) followed by dispersive solid-phase extraction (d-SPE) using graphitized carbon black (GCB) for cleanup was used before LC-MS/MS analysis. Different parameters were optimized, including the type and volume of extractants, vortex time, and the type and amount of adsorbents used for cleanup. The evaluation showed that the method has excellent linearity (R2 ≥ 0.994). The recovered 8 BPUs insecticides from spiked tomato and cucumber samples at 0.01, 0.05, and 0.25 mg kg−1 ranged from 83.2 to 105.2%, with RSD of 4.9–14.6%. The limits of quantitation (LOQs) were 0.0025 mg kg−1 (0.005 mg kg−1 for lufenuron). Within-day repeatability ranged from 3.9 to 13.9%, while between-day repeatability ranged from 8.9% to 17.7%. The optimized method was used to analyze 100 samples of tomatoes and cucumbers marketed in Saudi Arabia.

Presence of foodborne pathogens and survival of generic Escherichia coli in an organic integrated crop-livestock system

IntroductionIntegrated crop-livestock systems (ICLS) use animals to graze crop residues or cover crops before planting fresh produce and provide ecosystem services to support organic vegetable production. However, there is a risk of foodborne pathogen transfer to fresh produce because grazing may introduce enteric foodborne pathogens into the soil via animal feces, which may subsequently be transferred to the produce.MethodsTo examine the effect of cover crop use and the risk of cover crop grazing on the contamination of soil and produce by foodborne pathogens in ICLS, a three-year (2019–2021) experimental study was conducted in organically managed plots, which were assigned three different treatments (fallow without cover crop or grazing, cover crop without grazing, or cover crop with grazing by sheep) in a maize/tomato rotation. During the three years of the experiment, a total of 184 pre- and post-graze fecal samples and 96 samples of tomatoes were collected to test for foodborne pathogens (Escherichia coli O157, non-O157 Shiga toxin-producing Escherichia coli (STEC), and Listeria (L.) monocytogenes). Soil samples were collected monthly until 126–171 days after grazing (824 in total) to examine the presence of foodborne pathogens, and generic E. coli (MPN/g) was quantified to compare its persistence among the three treatments.Results and DiscussionWe did not detect any foodborne pathogens from harvested tomatoes in 2020 and 2021. One non-O157 STEC positive soil sample (0.1%, 1/824) was detected in the fallow treatment, and one L. monocytogenes-positive (1.1%, 1/92) was detected from the post-graze fecal samples. When assessing proportions of generic E. coli positive and counts of generic E. coli in the soil samples using mixed effect zero-inflated negative binomial models, soil samples collected in the graze cover crop treatment plot showed significant increases in the counts of generic E. coli until 61–82 days post grazing, but no difference was observed after 96–123 days, compared to the baseline of the fallow treatment. Findings from generic E. coli counts support the use of the United States Department of Agriculture (USDA) National Organic Program (NOP) 90- or 120-day interval rule between applying raw manure and harvesting in organic farming into ICLS. Additionally, we confirmed that commercial organic compost application before cover crop seeding in the winter had no significant effect on the proportions and counts of generic E. coli in the soil of the following growing seasons. This longitudinal field trial confirmed that the effect of sheep grazing on foodborne pathogen contamination in ICLS is minimal but further studies comparing the genetic associations between fecal and soil samples would be necessary to distinguish the source of foodborne pathogen contamination.

First Report of Fruit Rot Caused by Fusarium luffae in Cherry Tomato in China.

Tomato (Solanum lycopersicum L.) is a fruit of great economic value that is grown worldwide. In November 2022, fruit rot symptoms were observed in cherry tomatoes (cv. Qianxi) in Jinan City of Shandong Province, China. Six cherry tomato samples (four symptomatic and two asymptomatic) were collected from commercial fields (approximately 1.2 ha) where the incidence of the disease ranged from 5 to 10%. The core and surface of the infected fruit were colonized and covered with white mycelia. Tissue pieces (5 mm × 5 mm) from the junction of healthy and diseased samples were surface-disinfected with 75% ethanol for 3 min, followed by 10% sodium hypochlorite for 5 min, and washed three times with sterile water. Tissue pieces were cultured on potato dextrose agar (PDA containing 200 mg/L timentin) at 28°C for five days. Four fungal isolates with similar morphological characteristics were obtained from each sample. Two representative isolates were collected and purified using the single-spore method. After five days on PDA at 28°C, FL1 and FL2 colonies showed abundant white to cream colored aerial mycelia with an average growth rate of 5 mm/day. On carnation leaf agar, FL1 was characterized by falcate macroconidia with pronounced dorsiventral curvature containing three to eight tapered apical cells and foot-shaped basal cells ranging in size from 25 to 74 μm × 3.6 to 6.8 μm (n=50). Microconidia and chlamydospores were not observed. These morphological characteristics were consistent with the description of F. luffae (Wang et al. 2019). DNA was extracted using the CTAB method. The nucleotide sequences of the translation elongation factor 1-α gene (TEF1) and the second largest RNA polymerase II subunit (RPB2) were amplified using specific primers EF1/EF2 and RPB2F/R, respectively (O'Donnell et al. 1998, 2010). FL1 and FL2 sequences were deposited in GenBank (TEF1: OQ427345 and OQ427346, RPB2: OQ427347 and OQ427348). Polyphasic identification indicated 100% similarity of FL1 and FL2 to F. luffae. A combined dataset of TEF1 and RPB2 was aligned using MAFFT v.7, and phylogenetic analysis was performed in MEGA v.7.0 using the maximum likelihood method. The cherry tomato isolates (FL1 and FL2) clustered together with the F. luffae reference strain NRRL31167 (100% bootstrap) and were identified on a morphological and molecular basis as F. luffae belonging to the Fusarium incarnatum-equiseti species complex. F. luffae was the only pathogen recovered from the infected fruit. To test for pathogenicity, healthy cherry tomato fruit were inoculated in a greenhouse (28°C, 12/12 h light/dark cycle, 90% relative humidity), six by wounded inoculation and six by nonwounded inoculation) with 10 μL conidial suspensions of isolate FL1 at 1 × 106 conidia/mL. Six wounded-treated cherry tomato fruit were used for the control. All cherry tomatoes were kept in a growth chamber at 28℃ with 90% relative humidity. After seven days, the inside of the wound inoculated fruit began to rot, expanding toward the surface and producing white mycelia. Two diseased cherry tomatoes were randomly selected for tissue isolation and F. luffae was re-isolated showing the same morphology as the FL1 isolate, thus fulfilling Koch's postulates. The nonwounded inoculated fruits and control cherry tomatoes remained asymptomatic with no pathogens recovered. This indicates that the wound is an important way for F. luffae to invade tomato, and fruit rot is caused by F. luffae's infection of tomato. To the best of our knowledge, F. luffae has caused fruit rot in muskmelon (Zhang et al. 2022), but this is the first report of fruit rot disease in cherry tomatoes caused by F. luffae in China. Since cherry tomatoes are an important commercial crop in China, F. luffae infection has the potential to pose a threat to the industry.

Rapid detection of tomato spotted wilt virus by real-time RT-LAMP and in-field application

Tomato spotted wilt virus (TSWV) is considered one of the most threatening viruses worldwide for different economically important agricultural crops. In this scenario, it is important to perform an early detection by laboratory tests to prevent TSWV spread. A rapid and sensitive TSWV detection protocol based on real time reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed in this work, also using cost-effective and simplified sample preparation procedure, to assess the suitability of the RT-LAMP assay in field conditions on tomato and pepper samples. A set of six primers was designed within the nucleotide sequence region coding for the nucleocapsid protein (N) of segment S, targeting a 220-nucleotide sequence. Sensitivity, specificity, accuracy, and in-field application of the real-time RT-LAMP assay were evaluated. The developed real-time RT-LAMP assay proved to be one thousand and one hundred times more sensitive than end-point RT-PCR and real-time RT-PCR methods, respectively, detecting a total of 9.191 × 101 genome copies as minimum target, and no cross-reactivity were detected with other viruses belonging to Tospoviridae and Bromoviridae families used as outgroup. In addition, the in-field application of the assay using the rapid sample preparation gave adequate and reliable results within 60 minutes, with an acceptable reaction delay when compared to canonical RNA extraction. The in-field analyses showed an increase of TSWV-positive samples (37%) detection compared with end-point RT-PCR and real-time RT-PCR (32% and 29%, respectively), particularly on asymptomatic samples, confirming that the real-time RT-LAMP assay can be implemented as a routine test both in-field and laboratory conditions as a rapid and sensitive technique for TSWV detection.

Biological Exploration and Physicochemical Characteristics of Tomato Brown Rugose Fruit Virus in Several Host Crops

Tomato brown rugose fruit virus (ToBRFV) is considered an emerging disease and a viral pandemic for tomato consumers. The objectives of this research were to analyze the biological and physicochemical characteristics of ToBRFV in tomato and tobacco plants, as well as to evaluate its natural host range. Inoculant seeds were recovered from ToBRFV-infected tomato samples in Coahuila, Mexico, and confirmed by RT-PCR. In the first greenhouse experiment, tomato plants of the F1 hybrid variety 172–300 (Yüksel), infected with ToBRFV, were used to evaluate viral inclusions (VI), dilution endpoint (DEP), the incubation period (IP), and latency period (LP). In a greenhouse experiment, Nicotiana longiflora plants were inoculated with ToBRFV to determine the in vitro longevity (IVL) and thermal inactivation (TI) of the virus in sap. Finally, the inoculation of tomato plants grown in open fields was carried out to evaluate transmission to natural hosts. The plants tested for possible ToBRFV reservoirs near the inoculum source were inspected and confirmed by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The results indicate that the VIs on tomato leaves manifested as X-bodies and rounded, stacked plaques within epidermal cells. The DEP required to induce the infection in plants was from a ToBRFV concentration of 1 × 10−5.5, the IP of ToBRFV occurred 9 to 12 days post-inoculation, and LP could be detected one day after inoculation. The TI of ToBRFV in N. longiflora plants occurred at 85 °C for 30 min. Ipomoea purpurea, Mirabilis jalapa, Clematis drummondii, and Solanum tuberosum were newly identified hosts of ToBRFV. The results found contribute to a better understanding of the impact of ToBRFV, managing and preventing the spread of ToBRFV in diverse environments.

Screening and optimization of polyhydroxybutyrate (PHB) by Lysinibacillus fusiformis from diverse environmental sources

The need to explore microbial strains inhabiting ecosystems capable of yielding bioplastics with high production capacity and environmental sustainability is particularly of noteworthy due to the negative impacts of petrochemical plastics on humans and the environment. This study thus focused on the identification of novel polyhydroxybutyrate (PHB) producers, coupled with the screening and optimization of PHB or bioplastics for maximum yield. Bacterial strains were isolated from incinerator dump-site soil, hydrocarbon soil, rhizosphere and bulk soil samples of tomato and okra biochar plants. The identification of isolates was carried out based on biochemical and molecular methods. Screening of bacterial isolates for PHB was conducted using Sudan stain and Bromothymol techniques. Optimization analysis for maximum PHB production conditions by potential PHB strains was carried out via response surface methodology using Box-Behnken design at pH (2–11); substrates: rice bran (1–5 g); and time (24–96 h). Results showed that 112 bacterial isolates were recovered from all the samples collected. Tomato plant biochar soil recorded the highest number of bacterial isolates (37), while hydrocarbon soil yielded the lowest number of bacterial isolates (16). Predominant genera are Micrococcus, Bacillus and Staphylococcus. Lysinibacillus fusiformis was revealed to be the most potent PHB producer. Among the 112 bacteria isolated, nine isolates (5 isolates from tomato plant biochar soil, 2 bacteria from okra plant biochar soil and a single bacterial isolate from an incinerator dump site and hydrocarbon soil) exhibited positive results in both Sudan black and bromothymol tests. Box-Behnken design indicated the optimal experimental conditions for PHB synthesis to be pH 7, 72 h and substrates of rice bran of 3 g. In conclusion, Lysinibacillus fusiformis obtained from a tomato biochar plant demonstrates a high potential for bioplastic synthesis utilizing agricultural waste (rice bran) as a cost-effective as well as sustainable carbon source and could be utilized for commercial-scale PHB production.

Sodium dodecyl sulfate-modified ZIF-8 for sensitive detection of tetracycline in foods under synergistic adsorption of sodium dodecyl sulfate

The abuse for tetracycline (TC) in animal husbandry causes the residue of TC in animal foods, and even in vegetables arised from the pollution of soil. The sensitive determination of TC is greatly significant for the safety monitoring of foods. Herein, sodium dodecyl sulfate (SDS) was self-assembled on zeolite imidazolate framework-8 (ZIF-8) via hydrophobic interaction. The sensitive fluorescent detection of TC was obtained based on ZIF-8@SDS as-synthesized. After adding TC to ZIF-8@SDS, the internal ZIF-8 sensitized the emission band of TC centered at 521 nm, and the external SDS adsorbed TC via hydrophobic and electrostatic interactions. On this basis, TC could be quantified by ZIF-8@SDS selectively in a concentration range from 0.01 to 60 μM within 1 min. Importantly, the synergistic adsorption effect of SDS promoted the sensitivity of ZIF-8@SDS, and the limit of detection as low as 9 nM was calculated toward TC. The concentrations of TC in fish and tomato samples were determined by ZIF-8@SDS. The relative standard deviations ranged from 1.1 % to 6.7 %, and the spiked recoveries were in the range of 85.2 %–116.2 %, proving the application potential of ZIF-8@SDS in food safety monitoring.