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FEMS Microbiology Ecology Apr 2024As an important habitat for microorganisms, the phyllosphere has a great impact on plant growth and health, and changes in phyllosphere microorganisms are closely...
As an important habitat for microorganisms, the phyllosphere has a great impact on plant growth and health, and changes in phyllosphere microorganisms are closely related to the occurrence of leaf diseases. However, there remains a limited understanding regarding alterations to the microbial community in the phyllosphere resulting from pathogen infections. Here, we analyzed and compared the differences in phyllosphere microorganisms of powdery mildew cucumber from three disease severity levels (0% < L1 < 30%, 30% ≤ L2 < 50%, L3 ≥ 50%, the number represents the lesion coverage rate of powdery mildew on leaves). There were significant differences in α diversity and community structure of phyllosphere communities under different disease levels. Disease severity altered the community structure of phyllosphere microorganisms, Rosenbergiella, Rickettsia, and Cladosporium accounted for the largest proportion in the L1 disease grade, while Bacillus, Pantoea, Kocuria, and Podosphaera had the highest relative abundance in the L3 disease grade. The co-occurrence network analysis of the phyllosphere microbial community indicated that the phyllosphere bacterial community was most affected by the severity of disease. Our results suggested that with the development of cucumber powdery mildew, the symbiotic relationship between species was broken, and the entire bacterial community tended to compete.
Topics: Cucumis sativus; Plant Diseases; Microbiota; Ascomycota; Plant Leaves; Bacteria; RNA, Ribosomal, 16S
PubMed: 38599637
DOI: 10.1093/femsec/fiae050 -
Plant Disease Apr 2024Rice (Oryza sativa L.) is a crucial staple crop worldwide, and bacterial diseases are among the primary factors affecting rice yield. In late October 2022, bacterial...
Rice (Oryza sativa L.) is a crucial staple crop worldwide, and bacterial diseases are among the primary factors affecting rice yield. In late October 2022, bacterial leaf streak disease was observed on the leaves of the rice variety Meixiangzhan 2 across multiple fields (approximately 130 hm2) in Leizhou City, Guangdong Province, China. The incidence rate was up to 30% in each field. Infected rice leaves exhibited distinctive symptoms at the boundary between diseased and healthy tissue, featuring dark green to yellow-brown streaks, while most of the leaf margin exhibited symptoms of either leaf edge or sheath rot. Disease progression from the leaf tip inwards revealed gray-white or dehydrated lesions with a bluish-gray color. Some leaves exhibited wrinkling at the edges, and severe symptoms at the leaf tip resembled those of bacterial leaf blight in rice. Ten leaves were collected from 10 infected rice plants in three distinct fields, and leaf pieces at the border of diseased and healthy areas were surface disinfected with 75% anhydrous ethanol for 60 seconds, rinsed three times with sterile water, and then soaked in sterile water for 8 hours. The obtained bacterial suspension was diluted at a ratio of 1: 106, and 100 μL of the diluted samples were plated on Potato Dextrose Agar (PDA) plates. After incubation at 28°C for 48 hours, the yellow bacterial colonies that appeared, were purified on PDA plates. To confirm the bacterial species, the amplification of genes gyrB, leuS, rpoB, and 16S rDNA was performed on six randomly selected isolates from the three different fields using the primers 27F/1492R, gyrB-F/R, leuS-F/R and rpoB-F/R, as reported by Yu et al (2022), respectively. PCR products were sequenced. All six isolates had identical sequences for all genes sequenced.The gene sequences of 16S rDNA (960 bp), gyrB (953 bp), leuS (733 bp), and rpoB (877 bp) for LZ1, were deposited in the NCBI database under accession numbers PP048830 , PP068625 , PP068626, and PP068627, respectively. These sequences were subsequently compared using BLASTn tool against the NCBI nr/nt database. The 16S rDNA, gyrB, leuS, and rpoB of LZ1 showed similarities of 99.90%, 99.16%, 99.73%, and 99.89%, with the corresponding sequences of P. ananatis TZ39 (GenBank accession numbers MZ800600.1 for 16S rDNA, and CP081342.1 for gyrB, leuS and rpoB ). MLSA analysis using concatenated sequences of gyrB, leuS, and rpoB genes indicated that the isolated strain LZ1 belongs to P. ananatis. In the tillering stage of rice varieties Meixiangzhan 2 and Huahangyuzhan, P. ananatis LZ1 was inoculated at a concentration of 108 CFU/mL using the leaf-cutting method, with sterile water used as a control (Toh et al., 2019). After 14 days of bacterial inoculation, the inoculated leaves gradually became necrotic, changing from light green to brown showing identical symptoms as those in the field, while the control plants remained symptom-free. Subsequent 16S rDNA, gyrB, leuS and rpoB gene sequencing results further confirmed the identity of the pathogen as P. ananatis, thereby fulfilling Koch's postulates. Previous reports have already identified P. ananatis as the pathogen causing rice bacterial leaf streak (Kini et al., 2017; Arayaskul et al., 2019; Yu et al., 2022; Lu et al., 2022; Luna et al., 2023; Yuan et al., 2023). This is the first report of rice bacterial leaf streak caused by P. ananatis in Guangdong Province, China, laying the foundation for future research to establish strategies for the prevention and control of this disease.
PubMed: 38595062
DOI: 10.1094/PDIS-02-24-0421-PDN -
Frontiers in Microbiology 2024P1 is a model, temperate bacteriophage of the 94 kb genome. It can lysogenize representatives of the order. In lysogens, it is maintained as a plasmid. We tested P1...
P1 is a model, temperate bacteriophage of the 94 kb genome. It can lysogenize representatives of the order. In lysogens, it is maintained as a plasmid. We tested P1 interactions with the biocontrol L15 strain to explore the utility of P1 in genome engineering. A P1 derivative carrying the Tn (cm) transposon could transfer a plasmid from to the L15 cells. The L15 cells infected with this derivative formed chloramphenicol-resistant colonies. They could grow in a liquid medium with chloramphenicol after adaptation and did not contain prophage P1 but the chromosomally inserted cm marker of P1 Tn (). The insertions were accompanied by various rearrangements upstream of the Tn gene promoter and the loss of IS (ISL) from the corresponding region. Sequence analysis of the L15 strain genome revealed a chromosome and three plasmids of 0.58, 0.18, and 0.07 Mb. The largest and the smallest plasmid appeared to encode partition and replication incompatibility determinants similar to those of prophage P1, respectively. In the L15 derivatives cured of the largest plasmid, P1 with Tn could not replace the smallest plasmid even if selected. However, it could replace the smallest and the largest plasmid of L15 if its Tn ISL sequence driving the Tn mobility was inactivated or if it was enriched with an immobile kanamycin resistance marker. Moreover, it could develop lytically in the L15 derivatives cured of both these plasmids. Clearly, under conditions of selection for P1, the mobility of the P1 selective marker determines whether or not the incoming P1 can outcompete the incompatible L15 resident plasmids. Our results demonstrate that can serve as a host for bacteriophage P1 and can be engineered with the help of this phage. They also provide an example of how antibiotics can modify the outcome of horizontal gene transfer in natural environments. Numerous plasmids of strains appear to contain determinants of replication or partition incompatibility with P1. Therefore, P1 with an immobile selective marker may be a tool of choice in curing these strains from the respective plasmids to facilitate their functional analysis.
PubMed: 38591037
DOI: 10.3389/fmicb.2024.1356206 -
Biomedical and Environmental Sciences :... Mar 2024The purpose of this study was to investigate the bacterial communities of biting midges and ticks collected from three sites in the Poyang Lake area, namely, Qunlu...
OBJECTIVE
The purpose of this study was to investigate the bacterial communities of biting midges and ticks collected from three sites in the Poyang Lake area, namely, Qunlu Practice Base, Peach Blossom Garden, and Huangtong Animal Husbandry, and whether vectors carry any bacterial pathogens that may cause diseases to humans, to provide scientific basis for prospective pathogen discovery and disease prevention and control.
METHODS
Using a metataxonomics approach in concert with full-length 16S rRNA gene sequencing and operational phylogenetic unit (OPU) analysis, we characterized the species-level microbial community structure of two important vector species, biting midges and ticks, including 33 arthropod samples comprising 3,885 individuals, collected around Poyang Lake.
RESULTS
A total of 662 OPUs were classified in biting midges, including 195 known species and 373 potentially new species, and 618 OPUs were classified in ticks, including 217 known species and 326 potentially new species. Surprisingly, OPUs with potentially pathogenicity were detected in both arthropod vectors, with 66 known species of biting midges reported to carry potential pathogens, including and , compared to 50 in ticks, such as and . We found that was the most dominant group in both midges and ticks. Furthermore, the outcomes demonstrated that the microbiota of midges and ticks tend to be governed by a few highly abundant bacteria. sp7 was predominant in biting midges, while sp1 was enriched in ticks. Meanwhile, spp., which may be essential for the survival of Neumann, were detected in all tick samples. The identification of dominant species and pathogens of biting midges and ticks in this study serves to broaden our knowledge associated to microbes of arthropod vectors.
CONCLUSION
Biting midges and ticks carry large numbers of known and potentially novel bacteria, and carry a wide range of potentially pathogenic bacteria, which may pose a risk of infection to humans and animals. The microbial communities of midges and ticks tend to be dominated by a few highly abundant bacteria.
Topics: Animals; Humans; Ticks; Ceratopogonidae; Phylogeny; RNA, Ribosomal, 16S; Prospective Studies; Microbiota; Coxiella
PubMed: 38582991
DOI: 10.3967/bes2024.030 -
Heliyon Apr 2024After harvesting, pathogens can infect fresh vegetables in different ways. Pathogenic bacteria associated with fresh vegetables can cause widespread epidemics associated...
After harvesting, pathogens can infect fresh vegetables in different ways. Pathogenic bacteria associated with fresh vegetables can cause widespread epidemics associated with foodborne illness. The aim of this study was to assess the microbiological quality of carrot slices after treatment with aqueous extracts of (AE) at different concentrations AE1 (10 mg/mL), AE2 (5 mg/mL), AE3 (2.5 mg/mL) and AE4 (1.25 mg/mL), and subsp. serovar Enteritidis, along with vacuum packaging and storage of carrots for 7 days at 4 °C. On days 1. and 7., total viable counts (TVC), and coliforms bacteria (CB), and count were all analysed. Microorganisms that were obtained from carrots were identified using MALDI-TOF MS Biotyper Mass Spectrometry. The total viable, coliform bacteria and counts were varied by the group of treatment. Higher counts were found in the control group on both days. The most isolated species of bacteria were and on the 1. day and on the 7. day. The current study adds useful information for a better understanding of how reacts to the effect of AE and its potential use as a sustainable washing method to eliminate bacteria from freshly cut carrots.
PubMed: 38576551
DOI: 10.1016/j.heliyon.2024.e29065 -
Frontiers in Microbiology 2024Lignocellulosic pretreatment is an important stage in biomass utilization, which usually requires high input. In this study, a low-cost method using combined ensiling...
Lignocellulosic pretreatment is an important stage in biomass utilization, which usually requires high input. In this study, a low-cost method using combined ensiling and NaOH was developed for lignocellulosic pretreatment. Sweet sorghum bagasse (SSB) was ensiled for 21 days and then treated with diluted NaOH (0%, 1%, and 2%) for fermentation. The results showed that the application of (L) reduced fermentation losses of the silages, mainly low water-soluble carbohydrate (WSC) and ammonia nitrogen loss. Meanwhile, the application of and ensiling enzyme (LE) promoted lignocellulosic degradation, as evidenced by low neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (ADL), and hemicellulosic (HC) contents. The dominant bacterial genera were , and after silage, which corresponded to the higher lactic acid and acetic contents and lower pH. The reducing sugar yields of SSB increased after combined pretreatment of silage and NaOH and were further enhanced by the 2% NaOH application, as evidenced by the high reducing sugar yield and microstructure damage, especially in the L-2% NaOH group and the LE-2% NaOH group, in which the reducing sugar yields were 87.99 and 94.45%, respectively, compared with those of the no additive control (CK)-0 NaOH group. Therefore, this study provides an effective method for SSB pretreatment to enhance biomass conservation.
PubMed: 38572245
DOI: 10.3389/fmicb.2024.1370686 -
Cell Reports Apr 2024The type VI secretion system (T6SS), a widespread protein delivery apparatus, plays a role in bacterial competition by delivering toxic effectors into neighboring cells....
The type VI secretion system (T6SS), a widespread protein delivery apparatus, plays a role in bacterial competition by delivering toxic effectors into neighboring cells. Identifying new T6SS effectors and deciphering the mechanism that governs their secretion remain major challenges. Here, we report two orphan antibacterial T6SS effectors in the pathogen Pantoea agglomerans (Pa). These effectors share an N-terminal domain, Pantoea type six (PIX), that defines a widespread class of polymorphic T6SS effectors in Enterobacterales. We show that the PIX domain is necessary and sufficient for T6SS-mediated effector secretion and that PIX binds to a specialized Pa VgrG protein outside its C-terminal toxic domain. Our findings underline the importance of identifying and characterizing delivery domains in polymorphic toxin classes as a tool to reveal effectors and shed light on effector delivery mechanisms.
Topics: Bacterial Proteins; Pantoea; Protein Binding; Protein Domains; Type VI Secretion Systems
PubMed: 38568810
DOI: 10.1016/j.celrep.2024.114015 -
Cureus Feb 2024The genus of bacteria is a group of Gram-negative rod-shaped bacteria in the Enterobacteriaceae family. It is an uncommon cause of infection in humans except in...
The genus of bacteria is a group of Gram-negative rod-shaped bacteria in the Enterobacteriaceae family. It is an uncommon cause of infection in humans except in specific settings, including hospital-acquired infections and in immunocompromised patients. In this report, we describe the case of a 12-year-old girl with sickle cell disease who presented with a picture of sepsis and was found to have species in her blood culture which was treated with antibiotics with a good response. From our literature review, risk factors were identified in the reported cases, for which further exploration is highly recommended.
PubMed: 38558673
DOI: 10.7759/cureus.55122 -
Journal of Food Protection May 2024Digital tools to predict produce shelf life have the potential to reduce food waste and improve consumer satisfaction. To address this need, we (i) performed an...
Digital tools to predict produce shelf life have the potential to reduce food waste and improve consumer satisfaction. To address this need, we (i) performed an observational study on the microbial quality of baby spinach, (ii) completed growth experiments of bacteria that are representative of the baby spinach microbiota, and (iii) developed an initial simulation model of bacterial growth on baby spinach. Our observational data showed that the predominant genera found on baby spinach were Pseudomonas, Pantoea and Exiguobacterium. Rifampicin-resistant mutants (rif mutants) of representative bacterial subtypes were subsequently generated to obtain strain-specific growth parameters on baby spinach. These experiments showed that: (i) it is difficult to select rif mutants that do not have fitness costs affecting growth (9 of 15 rif mutants showed substantial differences in growth, compared to their corresponding wild-type strain) and (ii) based on estimates from primary growth models, the mean (geometric) maximum population of rif mutants on baby spinach (7.6 log CFU/g, at 6°C) appears lower than that of the spinach microbiota (9.6 log CFU/g, at 6°C), even if rif mutants did not have substantial growth-related fitness costs. Thus, a simulation model, parameterized with the data obtained here as well as literature data on home refrigeration temperatures, underestimated bacterial growth on baby spinach. The root mean square error of the simulation's output, compared against data from the observational study, was 1.11 log CFU/g. Sensitivity analysis was used to identify key parameters (e.g., strain maximum population) that impact the simulation model's output, allowing for prioritization of future data collection to improve the simulation model. Overall, this study provides a roadmap for the development of models to predict bacterial growth on leafy vegetables with strain-specific parameters and suggests that additional data are required to improve these models.
Topics: Spinacia oleracea; Food Microbiology; Colony Count, Microbial; Bacteria; Humans; Food Contamination
PubMed: 38552796
DOI: 10.1016/j.jfp.2024.100270 -
Veterinary Medicine and Science May 2024Ruminant mastitis continues to be a cause of economic losses in the dairy industry and remains a major public health hazard globally.
BACKGROUND
Ruminant mastitis continues to be a cause of economic losses in the dairy industry and remains a major public health hazard globally.
OBJECTIVES
This cross-sectional study was carried out in Mukurweini Sub-County of Nyeri County, Kenya, to investigate the prevalence of bacteria causing mastitis, risk factors associated with goat mastitis and the antibiotic resistance profiles of bacteria isolated from the goat milk.
METHODS
Farm level data on risk factors for mastitis was obtained from 56 farmers using a semi structured questionnaire. A total of 189 goat milk samples were collected. The goat's udder was observed for signs of clinical mastitis and the California Mastitis Test (CMT) used to test the milk for sub-clinical mastitis. All samples were then cultured for morphological identification of bacteria and strain typing by Matrix Assisted Laser Desorption/Ionization (MALDI)-Time of Flight (ToF) technique. Antimicrobial susceptibility of the isolated Staphylococcus aureus, coagulase-negative Staphylococcus (CoNS), Escherichia coli, Klebsiella oxytoca, Pseudomonas spp., Enterobacter spp., Proteus vulgaris and Escherichia vulneris to eight commonly used antibiotics was done by the disc diffusion method and validated by determining the presence of antibiotic resistance genes (mecA and blaTEM) using polymerase chain reaction method.
RESULTS
The prevalence of clinical mastitis was 1.1% (2/189) while that of sub-clinical mastitis was 84.7% (160/189). Higher (p < 0.05) prevalence of mastitis was observed in goats whose houses were cleaned fortnightly and in cases where farmers used same towel to dry different does' udders during the milking process. Thirteen different bacterial species were isolated from the milk samples and identified by MALDI-ToF, and these included S. aureus (22.0%), CoNS (20.3%), E. coli (18.1%), Pseudomonas spp. (14.3%), Enterobacter spp. (10.4%), K. oxytoca (6.0%), E. vulneris (1.7%), P. vulgaris (1.7%), Raoutella ornithinolytica (1.7%), Stenotrophomonas maltophilia (1.1%), Pantoea agglomerans (1.1%), Serratia marcescens (1.1%) and Cedeceas spp. (0.6%). One hundred pathogenic bacterial isolates were randomly selected and tested for antibiotic sensitivity to eight antibiotics out of which S. aureus were 97.5% resistant to Oxacillin and 100% sensitive to Ciprofloxacin. The CoNSs were 100% resistant to Oxacillin and 100% sensitive to Ciprofloxacin. E. coli were 93.9% resistant to Oxacillin, 69.7% sensitive to Ciprofloxacin and 87.9% sensitive to both Amoxicillin/Clavulanic acid and Meropenem. The antimicrobial resistant genes detected in S. aureus and E. coli were mecA [66.7%, 0%], and bla [20% and 78.3%], respectively.
CONCLUSION
In conclusion, the study showed that most of the does were affected by subclinical mastitis with the main causative bacteria being Staphylococci spp. and coliforms. Farmers need to be trained on improved control of mastitis by adoption of good milking practices and use of CMT kit for early detection of mastitis. Occurrence of multidrug resistance by key mastitis causing pathogens was shown to be prevalent and therefore there is need for development of intervention strategies.
Topics: Female; Animals; Anti-Bacterial Agents; Staphylococcus aureus; Escherichia coli; Prevalence; Kenya; Cross-Sectional Studies; Drug Resistance, Bacterial; Staphylococcus; Bacteria; Oxacillin; Anti-Infective Agents; Ciprofloxacin; Mastitis; Goats; Goat Diseases
PubMed: 38546016
DOI: 10.1002/vms3.1420