Complete genome sequences of Enterococcus casseliflavus strains ASE2 and ASE4 generated by PacBio sequencing.

Enterococcus casseliflavus strains ASE2 and ASE4 were isolated from the soil of a lettuce farm in Salinas, California, in 2020. Their complete genome sequences were generated by the PacBio Sequel II platform. They both consist of a single circular chromosome without plasmids.

Evaluation of lyophilized bacteriophage cocktail efficiency against multidrug-resistant Salmonella in broiler chickens.

Currently, phage biocontrol is increasingly used as a green and natural technology for treating Salmonella and other infections, but phages exhibit instability and activity loss during storage. Therefore, in this study, the effects of lyophilization on the activity and stability of phage cocktails for the control of multidrug-resistant Salmonella in broiler chickens were determined. Eight serotypes of Salmonella were isolated and identified from broiler chicken farms, and bacteriophages against multidrug-resistant Salmonella enterica subsp. enterica serovar Kentucky, Salmonella enterica subsp. enterica serovar Typhimrium and Salmonella enterica subsp. enterica serovar Enteritidis were isolated. The bacteriophage cocktail was prepared and lyophilized, and it was subjected to in vitro and in vivo examinations. A reconstituted lyophilized bacteriophage cocktail was used for the oral treatment of chicks before and after challenge with multidrug-resistant S. Kentucky. The colonization of cecum by S. Kentucky was detected by using real-time PCR, and the serum levels of IgM, IgA and IL-4 and pathological changes in the different groups were detected. Three Caudovirales phages families were identified including Autographiviridae, Straboviridae and Drexlerviridae against multidrug-resistant S. Kentucky, S. Typhimrium and S. Enteritidis. The groups treated with the bacteriophage cocktail showed no clinical signs, no postmortem lesions, and a mortality rate of 0%, which improved the growth performance parameters. Additionally, the estimated serum levels of IgM, IgA and IL-4 were significantly greater in the bacteriophage cocktail-treated groups. Lyophilization effectively preserves the long-term storage stability of phages. Therefore, lyophilized bacteriophage cocktail therapy is a valuable approach for controlling multidrug-resistant Salmonella infections in broiler chickens.

The decision for or against mycoparasitic attack by Trichoderma spp. is taken already at a distance in a prey-specific manner and benefits plant-beneficial interactions.

BACKGROUND: The application of plant-beneficial microorganisms as bio-fertilizer and biocontrol agents has gained traction in recent years, as both agriculture and forestry are facing the challenges of poor soils and climate change. Trichoderma spp. are gaining popularity in agriculture and forestry due to their multifaceted roles in promoting plant growth through e.g. nutrient translocation, hormone production, induction of plant systemic resistance, but also direct antagonism of other fungi. However, the mycotrophic nature of the genus bears the risk of possible interference with other native plant-beneficial fungi, such as ectomycorrhiza, in the rhizosphere. Such interference could yield unpredictable consequences for the host plants of these ecosystems. So far, it remains unclear, whether Trichoderma is able to differentiate between plant-beneficial and plant-pathogenic fungi during the process of plant colonization. RESULTS: We investigated whether Trichoderma spp. can differentiate between beneficial ectomycorrhizal fungi (represented by Laccaria bicolor and Hebeloma cylindrosporum) and pathogenic fungi (represented by Fusarium graminearum and Alternaria alternata) in different confrontation scenarios, including a newly developed olfactometer "race tube"-like system. Using two independent species, T. harzianum and T. atrobrunneum, with plant-growth-promoting and immune-stimulating properties towards Populus x canescens, our study revealed robustly accelerated growth towards phytopathogens, while showing a contrary response to ectomycorrhizal fungi. Transcriptomic analyses identified distinct genetic programs during interaction corresponding to the lifestyles, emphasizing the expression of mycoparasitism-related genes only in the presence of phytopathogens. CONCLUSION: The findings reveal a critical mode of fungal community interactions belowground and suggest that Trichoderma spp. can distinguish between fungal partners of different lifestyles already at a distance. This sheds light on the entangled interactions of fungi in the rhizosphere and emphasizes the potential benefits of using Trichoderma spp. as a biocontrol agent and bio-fertilizer in tree plantations.

Chemical and genetic characterization of lipopeptides from Bacillus velezensis and Paenibacillus ottowii with activity against Fusarium verticillioides.

Introduction: The fungus Fusarium verticillioides significantly threatens maize crops in tropical soils. In light of this, biological control has emerged as a promising strategy to reduce fungicide costs and environmental risks. In this study, we aimed to test the antifungal activity of cell-free supernatant (CFS) from three Bacillus velezensis (CT02, IM14, and LIS05) and one Paenibacillus ottowii (LIS04) against F. verticillioides, thereby contributing to the development of effective biocontrol measures. Methods: The research employed a comprehensive approach. The antifungal activity of the bacterial strains was tested using cell-free supernatant (CFS) from three Bacillus velezensis (CT02, IM14, and LIS05) and one Paenibacillus ottowii (LIS04). The UPLC-MS evaluated the CFS to identify the main bioactive molecules involved in the inhibitory effect on F. verticillioides. Scanning electron microscopy (SEM) was used to assess the impact of CFS on spores and hyphae, and genome sequencing was conducted to identify the genes involved in biological control. These robust methodologies ensure the reliability and validate our findings. Results: The CFS of the four strains demonstrated significant inhibition of fungal growth. The UPLC-MS analysis revealed the presence of lipopeptides with antifungal activity, including surfactin and fengycins A and B expressed by the three strains of Bacillus velezensis and iturin A expressed by strains LIS05 and IM14. For Paenibacillus ottowii, fusaricidins, ABCDE, and five previously unreported lipopeptides were detected. Scanning electron microscopy (SEM) showed that treatments with CFS led to significant distortion and breakage of the F. verticillioides hyphae, in addition to the formation of cavities in the membrane. Genome mining confirmed the presence of genes coding for the lipopeptides identified by UPLC-MS, including the gene for iturin in CTO2. Genomic sequencing revealed that CT02, IM14, and LIS05 belong to different strains of Bacillus velezensis, and LIS04 belongs to Paenibacillus ottowii, a species recently described. Discussion: The four bacterial strains, including three novel strains identified as Bacillus velezensis and one as the recently described species Paenibacillus ottowii, demonstrate significant potential as biocontrol agents for managing fungal disease. This finding underscores the novelty and potential impact of our research.

Soil inhabiting bacto-helmith complex in insect pest management: Current research and future challenges.

Pesticides have health consequences for humans, living organisms, and ecosystems. Research on biological management, with a primary focus on entomopathogens, has been accelerated by the rise in issues such as pesticide residue, soil degradation, and pest resistance. Entomopathogenic nematodes (EPNs) are among the most frequently used and commercialised biopesticides. However, they are restricted in their infectivity, persistence, storage, and cost of production. The nematodes, along with their endosymbiotic bacteria, combine to form a nemato-bacterial complex. This complex is responsible for causing mortality in insect pests due to the production of insecticidal compounds. The adaptation of EPNs is an eco-friendly method, economical, and safer for the environment as well as non-target organisms. Moreover, it's a better alternative to synthetic chemical pesticides, as it can be helpful in overcoming pest resistance and resurgence issues. Application of nematode juveniles is a cost-effective method, but the necessity of refrigeration and transportation may enhance their cost. This review emphasised the diversity of entomopathogenic nematodes and their endosymbiotic bacteria, the exploration of the biocontrol potential of insect pests by under-utilisation of nematodes, the development of nematode-based formulations, and the discussion of critical issues and required research in the future.

Synergistic antibacterial activity of Lactococcus lactis and Xylella phage MATE 2 for an effective biocontrol strategy against black rot disease in broccoli.

Black rot, caused by Xanthomonas campestris pv. campestris (Xcc), is considered the most destructive disease affecting cruciferous vegetables, resulting in significant losses worldwide. The need for biocontrol agents against Xcc that can reduce reliance on chemical pesticides, enhance sustainability, and ensure crops and environmental health is crucial. Combining phages with other antibacterial agents (i.e., antibiotics and bacteriocins) to treat bacterial infections is gaining increased attention due to the frequently observed synergistic effects. This study introduces for the first time the combination of a lytic phage, i.e., Xylella phage MATE 2 (MATE 2) with nisin-producing Lactococcus lactis subsp. lactis (L. lactis) bacterium as an eco-friendly, cost-effective, and practical strategy for controlling Xcc in cruciferous vegetables. The antibacterial efficacy of MATE 2 and L. lactis, individually and in combination, against Xcc was investigated through a series of in vitro assays and in planta experiments conducted on broccoli plants. The time-killing curves results showed that under conditions of reduced Xcc population concentration (103 CFU/mL), MATE 2 at 108 PFU/mL exerted a persistent inhibitory effect on Xcc growth for 7 days. The Spot assays and v-qPCR analysis showed that both L. lactis and its bacteriocin nisin have significant antibacterial potential to contrast Xcc. Furthermore, combined application of MATE 2 and L. lactis in broccoli plants by foliar spraying generated significant synergistic efficacy in preventing Xcc infections, achieving a 71% reduction in symptoms, compared with 64 and 38% for single applications, respectively. In this study, the positive synergistic effect of the combined application of phage and beneficial bacteria in preventing black rot disease underscores this eco-friendly and cost-effective approach as a promising control measure against plant bacterial diseases.

Double-Wing Motif Protein is a Novel Biofilm Regulatory Factor of the Plant Disease Biocontrol Agent, Bacillus subtilis.

Transposon mutagenesis screening of Bacillus subtilis YB-1471, a novel rhizosphere biocontrol agent of Fusarium crown rot (FCR) of wheat, resulted in the identification of orf04391, linked to reduced biofilm formation. The gene encodes a protein possessing a putative tertiary structure of a "double-wing" DNA-binding domain. Expression of orf04391 increased during biofilm development in stationary cultures and during rapid growth in shaking cultures. An orf04391 deletion strain showed reduced biofilm production related to lower levels of the extracellular matrix, and the mutant also had reduced sporulation, adhesion, root colonization, and FCR biocontrol efficiency. Transcriptome analysis of YB-1471 and Δorf04391 in stationary culture showed that the loss of orf04391 resulted in altered expression of numerous genes, including sinI, an initiator of biofilm formation. DNA binding was shown with his-tagged Orf04391 binding to the sinIR operon in vivo and in vitro. Orf04391 appears to be a transcriptional regulator of biofilm formation in B. subtilis through the Spo0A-SinI/SinR pathway.

Prophylactic phage biocontrol prevents Burkholderia gladioli infection in a quantitative ex planta model of bacterial virulence.

Agricultural crop yield losses and food destruction due to infections by phytopathogenic bacteria such as Burkholderia gladioli, which causes devastating diseases in onion, mushroom, corn, and rice crops, pose major threats to worldwide food security and cause enormous damage to the global economy. Biocontrol using bacteriophages has emerged as a promising strategy against a number of phytopathogenic species but has never been attempted against B. gladioli due to a lack of quantitative infection models and a scarcity of phages targeting this specific pathogen. In this study, we present a novel, procedurally straightforward, and highly generalizable fully quantitative ex planta maceration model and an accompanying quantitative metric, the ex planta maceration index (xPMI). In utilizing this model to test the ex planta virulence of a panel of 12 strains of B. gladioli in Allium cepa and Agaricus bisporus, we uncover substantial temperature-, host-, and strain-dependent diversity in the virulence of this fascinating pathogenic species. Crucially, we demonstrate that Burkholderia phages KS12 and AH2, respectively, prevent and reduce infection-associated onion tissue destruction, measured through significant (P < 0.0001) reductions in xPMI, by phytopathogenic strains of B. gladioli, thereby demonstrating the potential of agricultural phage biocontrol targeting this problematic microorganism.IMPORTANCEAgricultural crop destruction is increasing due to infections caused by bacteria such as Burkholderia gladioli, which causes plant tissue diseases in onion, mushroom, corn, and rice crops. These bacteria pose a major threat to worldwide food production, which, in turn, damages the global economy. One potential solution being investigated to prevent bacterial infections of plants is "biocontrol" using bacteriophages (or phages), which are bacterial viruses that readily infect and destroy bacterial cells. In this article, we demonstrate that Burkholderia phages KS12 and AH2 prevent or reduce infection-associated plant tissue destruction caused by strains of B. gladioli, thereby demonstrating the inherent potential of agricultural phage biocontrol.

Innovative sustainable bioreactor-in-a-granule formulation of Trichoderma asperelloides.

The advancement of fungal biocontrol agents depends on replacing cereal grains with low-cost agro-industrial byproducts for their economical mass production and development of stable formulations. We propose an innovative approach to develop a rice flour-based formulation of the beneficial biocontrol agent Trichoderma asperelloides CMAA1584 designed to simulate a micro-bioreactor within the concept of full biorefinery process, affording in situ conidiation, extended shelf-life, and effective control of Sclerotinia sclerotiorum, a devastating pathogen of several dicot agricultural crops worldwide. Rice flour is an inexpensive and underexplored byproduct derived from broken rice after milling, capable of sustaining high yields of conidial production through our optimized fermentation-formulation route. Conidial yield was mainly influenced by nitrogen content (0.1% w/w) added to the rice meal coupled with the fermentor type. Hydrolyzed yeast was the best nitrogen source yielding 2.6 × 109 colony-forming units (CFU)/g within 14 days. Subsequently, GControl, GLecithin, GBreak-Thru, GBentonite, and GOrganic compost+Break-Thru formulations were obtained by extrusion followed by air-drying and further assessed for their potential to induce secondary sporulation in situ, storage stability, and efficacy against Sclerotinia. GControl, GBreak-Thru, GBentonite, and GOrganic compost+Break-Thru stood out with the highest number of CFU after sporulation upon re-hydration on water-agar medium. Shelf-life of formulations GControl and GBentonite remained consistent for > 3 months at ambient temperature, while in GBentonite and GOrganic compost+Break-Thru formulations remained viable for 24 months during refrigerated storage. Formulations exhibited similar efficacy in suppressing the myceliogenic germination of Sclerotinia irrespective of their concentration tested (5 × 104 to 5 × 106 CFU/g of soil), resulting in 79.2 to 93.7% relative inhibition. Noteworthily, all 24-month-old formulations kept under cold storage successfully suppressed sclerotia. This work provides an environmentally friendly bioprocess method using rice flour as the main feedstock to develop waste-free granular formulations of Trichoderma conidia that are effective in suppressing Sclerotinia while also improving biopesticide shelf-life. KEY POINTS: • Innovative "bioreactor-in-a-granule" system for T. asperelloides is devised. • Dry granules of aerial conidia remain highly viable for 24 months at 4 °C. • Effective control of white-mold sclerotia via soil application of Trichoderma-based granules.

Multi-metal tolerant Porostereum umbrinoalutaceum isolated from Pleurotus ostreatus fruit body showing root colonization, growth promotion of chilli (Capsicum annuum L.) plant and antagonism against fungal pathogens.

Mushroom associated microbes could be utilized to improve crop productivity providing nutrients, plant growth promoting substances, production of hydrolytic enzymes and protecting plant from biotic and abiotic stress. An endophyte designated as KUFC101 was isolated from fruit body of Pleurotus ostreatus and identified as Porostereum umbrinoalutaceum based on nuclear-rRNA gene sequence analysis. Growth in different culture media, metal tolerance, biochemical characterization and effect on chilli plant growth promotion were studied. The isolate showed best growth in Malt extract medium and least growth in synthetic media. It could tolerate toxic metals (Mg, Ca, Fe, Cu, Mn, Zn and Cd each at 100 ppm concentration). It produced amylase, cellulase, chitinase, pectinase, catecholate type of siderophore and indole acetic acid, and inhibited growth of Alternaria solani and Penicillium citrinum. It could colonize in the rhizosphere of chilli plant and influence growth of chilli plant by improving biomass and metabolite content. Porostereum umbrinoalutaceum KUFC101 could be utilized in formulation of biofertiliser under sustainable agricultural system.

Complete genome sequence of bacterium Peribacillus simplex strain IMGN11 from soil.

We report the complete genome sequence of Peribacillus simplex, a spore-forming bacterium originally classified within the Bacillus genus. Peribacillus simplex exhibits antibiotic, plant growth-promoting, and xenobiotic-degrading activities and resistance to environmental contamination. The genome sequence of Peribacillus simplex will provide insights into its capabilities and potential as a biocontrol agent.

Coating seeds with biocontrol bacteria-loaded sodium alginate/pectin hydrogel enhances the survival of bacteria and control efficacy against soil-borne vegetable diseases.

Microbial seed coatings serve as effective, labor-saving, and ecofriendly means of controlling soil-borne plant diseases. However, the survival of microbial agents on seed surfaces and in the rhizosphere remains a crucial challenge. In this work, we embedded a biocontrol bacteria (Bacillus subtilis ZF71) in sodium alginate (SA)/pectin (PC) hydrogel as a seed coating agent to control Fusarium root rot in cucumber. The formula of SA/PC hydrogel was optimized with the highest coating uniformity of 90 % in cucumber seeds. SA/PC hydrogel was characterized using rheological, gel content, and water content tests, thermal gravimetric analysis, and Fourier transform infrared spectroscopy. Bacillus subtilis ZF71 within the SA/PC hydrogel network formed a biofilm-like structure with a high viable cell content (8.30 log CFU/seed). After 37 days of storage, there was still a high number of Bacillus subtilis ZF71 cells (7.23 log CFU/seed) surviving on the surface of cucumber seeds. Pot experiments revealed a higher control efficiency against Fusarium root rot in ZF71-SA/PC cucumber seeds (53.26 %) compared with roots irrigated with a ZF71 suspension. Overall, this study introduced a promising microbial seed coating strategy based on biofilm formation that improved performance against soil-borne plant diseases.

Streptomyces avermitilis MICNEMA2022: a new biorational strain for producing abamectin as an integrated nematode management agent.

BACKGROUND: Abamectin (ABA) is considered a powerful insecticidal and anthelmintic agent. It is an intracellular product of Streptomyces avermitilis; is synthesized through complicated pathways and can then be extracted from mycelial by methanol extraction. ABA serves as a biological control substance against the root-knot nematode Meloidogyne incognita. This investigation is intended to reach a new strain of S. avermitilis capable of producing ABA effectively. RESULTS: Among the sixty actinobacterial isolates, Streptomyces St.53 isolate was chosen for its superior nematicidal effectiveness. The mycelial-methanol extract of isolate St.53 exhibited a maximum in vitro mortality of 100% in one day. In the greenhouse experiment, the mycelial-methanol extract demonstrated, for the second-stage juveniles (J2s), 75.69% nematode reduction and 0.84 reproduction rate (Rr) while for the second-stage juveniles (J2s), the culture suspension demonstrated 75.38% nematode reduction and 0.80 reproduction rate (Rr). Molecular identification for St.53 was performed using 16 S rRNA gene analysis and recorded in NCBI Genbank as S. avermitilis MICNEMA2022 with accession number (OP108264.1). LC-MS was utilized to detect and identify abamectin in extracts while HPLC analysis was carried out for quantitative determination. Both abamectin B1a and abamectin B1b were produced and detected at retention times of 4.572 and 3.890 min respectively. CONCLUSION: Streptomyces avermitilis MICNEMA2022 proved to be an effective source for producing abamectin as a biorational agent for integrated nematode management.

Biocontrol of plant parasitic nematodes by bacteria and fungi: a multi-omics approach for the exploration of novel nematicides in sustainable agriculture.

Plant parasitic nematodes (PPNs) pose a significant threat to global crop productivity, causing an estimated annual loss of US $157 billion in the agriculture industry. While synthetic chemical nematicides can effectively control PPNs, their overuse has detrimental effects on human health and the environment. Biocontrol agents (BCAs), such as bacteria and fungi in the rhizosphere, are safe and promising alternatives for PPNs control. These BCAs interact with plant roots and produce extracellular enzymes, secondary metabolites, toxins, and volatile organic compounds (VOCs) to suppress nematodes. Plant root exudates also play a crucial role in attracting beneficial microbes toward infested roots. The complex interaction between plants and microbes in the rhizosphere against PPNs is mostly untapped which opens new avenues for discovering novel nematicides through multi-omics techniques. Advanced omics approaches, including metagenomics, transcriptomics, proteomics, and metabolomics, have led to the discovery of nematicidal compounds. This review summarizes the status of bacterial and fungal biocontrol strategies and their mechanisms for PPNs control. The importance of omics-based approaches for the exploration of novel nematicides and future directions in the biocontrol of PPNs are also addressed. The review highlighted the potential significance of multi-omics techniques in biocontrol of PPNs to ensure sustainable agriculture.

Characterization of differences in seed endophytic microbiome in conventional and organic rice by amplicon-based sequencing and culturing methods.

The seed serves as the primary source for establishing microbial populations in plants across subsequent generations, influencing plant growth and overall health. Cropping conditions, especially farming practices, can influence the composition and functionality of the seed microbiome. Very little is known about the differences in seed microbiome between organic and conventional production systems. In this study, we characterized the endophytic microbial populations in seeds of rice grown under organic and conventional management practices through culture-dependent and -independent analyses. The V4 region of 16S rRNA was used for bacterial taxa identification, and the ITS1 region was used for the identification of fungal taxa. Our results revealed significantly higher Shannon and Simpson indices for bacterial diversity in the conventional farming system, whereas the fungal diversity was higher for observed, Shannon, and Simpson indices in the organic farming system. The cultivable endophytic bacteria were isolated and identified using the full-length 16S rRNA gene. There was no difference in culturable endophytic bacterial isolates in rice seeds grown under both conventional and organic farming systems. Among 33 unique isolates tested in vitro, three bacteria-Bacillus sp. ST24, Burkholderia sp. OR5, and Pantoea sp. ST25-showed antagonistic activities against Marasmius graminum, Rhizoctonia solani AG4, and R. solani AG11, the fungal pathogens causing seedling blight in rice. IMPORTANCE: In this paper, we studied the differences in the endophytic microbial composition of rice seeds grown in conventional and organic farming systems. Our results demonstrate a greater bacterial diversity in conventional farming, while organic farming showcases a higher fungal diversity. Additionally, our research reveals the ability of seed bacterial endophytes to inhibit the growth of three fungal pathogens responsible for causing seedling blight in rice. This study provides valuable insights into the potential use of beneficial seed microbial endophytes for developing a novel microbiome-based strategy in the management of rice diseases. Such an approach has the potential to enhance overall plant health and improve crop productivity.

Isolation, characterization, and application of a lytic bacteriophage SSP49 to control Staphylococcus aureus contamination on baby spinach leaves.

Staphylococcus aureus, a major foodborne pathogen, is frequently detected in fresh produce. It often causes food poisoning accompanied by abdominal pain, diarrhea, and vomiting. Additionally, the abuse of antibiotics to control S. aureus has resulted in the emergence of antibiotics-resistant bacteria, such as methicillin resistant S. aureus. Therefore, bacteriophage, a natural antimicrobial agent, has been suggested as an alternative to antibiotics. In this study, a lytic phage SSP49 that specifically infects S. aureus was isolated from a sewage sample, and its morphological, biological, and genetic characteristics were determined. We found that phage SSP49 belongs to the Straboviridae family (Caudoviricetes class) and maintained host growth inhibition for 30 h in vitro. In addition, it showed high host specificity and a broad host range against various S. aureus strains. Receptor analysis revealed that phage SSP49 utilized cell wall teichoic acid as a host receptor. Whole genome sequencing revealed that the genome size of SSP49 was 137,283 bp and it contained 191 open reading frames. The genome of phage SSP49 did not contain genes related to lysogen formation, bacterial toxicity, and antibiotic resistance, suggesting its safety in food application. The activity of phage SSP49 was considerably stable under various high temperature and pH conditions. Furthermore, phage SSP49 effectively inhibited S. aureus growth on baby spinach leaves both at 4 °C and 25 °C while maintaining the numbers of active phage during treatments (reductions of 1.2 and 2.1 log CFU/cm2, respectively). Thus, this study demonstrated the potential of phage SSP49 as an alternative natural biocontrol agent against S. aureus contamination in fresh produce.

Alginate coatings applied on apple cubes as a vehicle for Lacticaseibacillus casei: probiotic viability and overall quality of a new functional product.

BACKGROUND: Worldwide, vegan and vegetarian lifestyles, as well as food allergies and intolerance (e.g. lactose intolerance and milk protein allergy) demand the development of alternatives to dairy-based probiotic foods. In the present study, probiotic Lacticaseibacillus casei CECT 9104 was added to alginate-based edible coatings enriched with inulin and oligofructose and applied to fresh-cut apple. Microbiological, physicochemical and sensory quality parameters of the apple cubes were monitored during 8 days of refrigerated storage. Lacticaseibacillus casei was tested for its antagonistic effect against inoculated Listeria innocua and Escherichia coli O157:H7. The viability of the probiotic strain during refrigerated storage and after simulated gastrointestinal digestion (GID) was evaluated. RESULTS: After 8 days of storage, 9.52-9.64 log colony-forming units (CFU) g-1 of L. casei were detected in apple samples. The functional apple cubes retained 8.31-8.43 log CFU g-1 of the probiotic after GID, without a significant effect of prebiotic addition. The microbiological quality and nutritional properties were maintained by the use of active coatings, whereas the sensory quality decreased after 8 days of storage. A bactericidal effect was exerted by the probiotic strain loaded in the coating against L. innocua artificially inoculated on apple cubes. Escherichia coli O157:H7 counts were reduced by 2.5 log after 8 days. CONCLUSION: This study has demonstrated the suitability of apple cubes as an alternative matrix to milk for carrying probiotic L. casei CECT 9104 and prebiotics, offering a promising alternative for the development of plant-based functional foods. © 2024 Society of Chemical Industry.

Biocontrol and growth promotion potential of Bacillus velezensis NT35 on Panax ginseng based on the multifunctional effect.

The Bacillus velezensis strain NT35, which has strong biocontrol ability, was isolated from the rhizosphere soil of Panax ginseng. The antifungal effects of the NT35 strain against the mycelium and spore growth of Ilyonectria robusta, which causes ginseng rusty root rot, were determined. The inhibitory rate of I. robusta mycelial growth was 94.12% when the concentration of the NT35 strain was 107 CFU·mL-1, and the inhibitory rates of I. robusta sporulation and spore germination reached 100 and 90.31%, respectively, when the concentration of the NT35 strain was 104 and 108 CFU·mL-1, respectively. Strain NT35 had good prevention effects against ginseng rust rot indoors and in the field with the control effect 51.99%, which was similar to that of commercial chemical and biocontrol agents. The labeled strain NT35-Rif160-Stre400 was obtained and colonized ginseng roots, leaves, stems and rhizosphere soil after 90 days. Bacillus velezensis NT35 can induce a significant increase in the expression of five defensive enzyme-encoding genes and ginsenoside biosynthesis-related genes in ginseng. In the rhizosphere soil, the four soil enzymes and the microbial community improved during different periods of ginseng growth in response to the biocontrol strain NT35. The NT35 strain can recruit several beneficial bacteria, such as Luteimonas, Nocardioides, Sphingomonas, and Gemmatimonas, from the rhizosphere soil and reduce the relative abundance of Ilyonectria, Fusarium, Neonectria and Dactylonectria, which cause root rot and rusty root rot in ginseng plants. The disease indices were significantly negatively correlated with the abundances of Sphingomonas and Trichoderma. Additionally, Sphingomonadales, Sphingomonadaceae and actinomycetes were significantly enriched under the NT35 treatment according to LEfSe analysis. These results lay the foundation for the development of a biological agent based on strain NT35.

Evaluating the efficacy of microbial antagonists in inducing resistance, promoting growth, and providing biological control against powdery mildew in wheat.

This study evaluates the biocontrol efficacy of three bacterial strains (Pseudomonas fluorescens DTPF-3, Bacillus amyloliquefaciens DTBA-11, and Bacillus subtilis DTBS-5) and two fungal strains (Trichoderma harzianum Pusa-5SD and Aspergillus niger An-27) antagonists, along with their combinations at varying doses (5.0, 7.5, and 10.0 g/kg of seeds), against wheat powdery mildew. The most effective dose (10 g/kg seeds) was further analyzed for its impact on induced resistance and plant growth promotion under greenhouse conditions. The study measured defense enzyme activities, biochemical changes, and post-infection plant growth metrics. All tested microbial antagonists at 10 g/kg significantly reduced PM severity, with B. subtilis strain DTBS-5 outperforming others in reducing PM severity and achieving the highest biocontrol efficacy. It was followed by B. amyloliquefaciens strain DTBA-11 and P. fluorescens strain DTPF-3, with the fungal antagonists showing no significant effect. Wheat crops treated with B. subtilis strain DTBS-5 exhibited substantial increases in defense-related enzyme activities and biochemicals, suggesting an induced resistance mechanism. The study found a 45% increase in peroxidase (POD) activity, a 50% increase in catalase (CAT) activity, a 30% increase in phenolic content, and a 25% increase in soluble protein content in the wheat plants treated with microbial antagonists. The study highlights the effectiveness of microbial antagonists, particularly B. subtilis strain DTBS-5, in managing wheat PM through biocontrol, induced resistance, and enhanced plant growth, offering a sustainable alternative to chemical treatments.