Microbiology Research

11 pages, 550 KB

Open AccessArticle

In Vitro Investigation of Traditional Medicine Recipes Used in Bukavu (DR-Congo) to Treat Trichophyton rubrum Dermatophytosis

by Alexis Cizungu Murhula, Valérie De Glas, Eléa Denil and Yves Poumay

Microbiol. Res. 2025, 16(10), 223; https://doi.org/10.3390/microbiolres16100223 - 10 Oct 2025

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Abstract

Twenty natural products used in traditional medicine to treat dermatophytosis were evaluated for their efficacy against Trichophyton rubrum, the most frequent dermatophyte infecting humans. For this purpose, aqueous and methanolic extracts were prepared from ash, honey, and plant organs as pure (100%) [...] Read more.

Twenty natural products used in traditional medicine to treat dermatophytosis were evaluated for their efficacy against Trichophyton rubrum, the most frequent dermatophyte infecting humans. For this purpose, aqueous and methanolic extracts were prepared from ash, honey, and plant organs as pure (100%) or diluted (75%, 50%, 25%, 12.5%, 6.25%, 3.125%, and 1.56%) preparations. The extracts were then evaluated by incorporating them into a Sabouraud medium and seeding them with T. rubrum as a fungal culture. The results identify fourteen extracts as being able to completely inhibit T. rubrum growth through either fungistatic or fungicidal activity. The five extracts with the highest efficacy to inhibit T. rubrum growth were further analyzed for their potential to alter in vitro reconstructed human epidermis (RHE). An aqueous extract from Allium sativum produced no tissue alteration in RHE, unlike the extracts from Conyza sumatrensis, Rumex abyssinicus, or Pentas longiflora. The data suggest that preparations used in traditional medicine by rural population in South-Kivu (DR-Congo) might represent valid alternatives to fight dermatophytosis. However, they also illustrate that several preparations remain inefficient and that others may be detrimental to the epidermis. This work reveals that traditional preparations, although affordable and easily available, require an evaluation of their efficacy and safety. Full article

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15 pages, 2231 KB

Open AccessArticle

Hydroxamic Acid Isolated from Maize Roots Exhibits Potent Antimicrobial Activity Against Pathogenic Escherichia coli in Broiler Chickens

by Qudrat Ullah, Shakoor Ahmad, Sarzamin Khan, Ijaz Ahmad, Samiullah Khan, Rajwali Khan and Farhan Anwar Khan

Microbiol. Res. 2025, 16(10), 222; https://doi.org/10.3390/microbiolres16100222 - 9 Oct 2025

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Abstract

Restrictions on adding antibiotics to animal diets have posed challenges in managing gut pathogens, emphasizing the significance of effective non-antibiotic growth promoters to maintain animal health and productivity. This study assessed the efficacy of hydroxamic acid (HA), derived from local maize varieties, as [...] Read more.

Restrictions on adding antibiotics to animal diets have posed challenges in managing gut pathogens, emphasizing the significance of effective non-antibiotic growth promoters to maintain animal health and productivity. This study assessed the efficacy of hydroxamic acid (HA), derived from local maize varieties, as a non-antibiotic growth promoter in broilers. Among 10 different maize varieties, the Azam variety yielded the highest HA concentration (35 ± 7 μg/g of roots), as quantified by high-performance liquid chromatography (HPLC). In vitro antimicrobial assays demonstrated the lowest minimum inhibitory concentration (MIC) of 0.022 mg for Azam-derived HA against pathogenic E. coli. To further assess in vivo efficacy, 108 birds were allocated at random to six treatment groups. The treatments include birds fed a basal diet without an E. coli challenge (negative control); an antibiotic-treated group challenged with E. coli and treated with enrofloxacin at a dosage of 5 milligrams (mg) per kilogram (kg), administered orally once daily from day 5 post-infection (dpi) for 7 consecutive days (standard); broilers challenged with E. coli and supplemented with a basal diet with HA at concentrations of 1, 10, or 100 mg/kg of feed from 5 dpi for one week (HA 1 mg, HA 10 mg, and HA 100 mg, respectively); and broilers challenged with E. coli without enrofloxacin/HA (positive control). The results demonstrated that birds fed a diet supplemented with the HA-100 mg improved the body weight (BW) and feed conversion ratio (FCR) compared to the positive control group. There were no significant differences (p > 0.05) observed for BW and FCR observed for the broilers fed on the standard and HA 100 mg groups. The addition of HA at 100 mg improved (p < 0.05) the hemoglobin (Hb) and packed cell volume (PCV) and reduced (p < 0.05) levels of malondialdehyde (MDA) compared to positive control group. A significantly low carcass weight (p < 0.05) was shown for positive control birds compared to other groups. Our findings indicate that maize-derived HA presents a phytogenic alternative to antibiotics by controlling enteric pathogens and improving health and performance affected by E. coli infection in broilers. Full article

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16 pages, 805 KB

Open AccessReview

Environmental Pathogen in Healthcare Settings: Candida auris—The Emerging Threat with a Focus on the Middle East and Infection Control Strategies

by Salma AlBahrani

Microbiol. Res. 2025, 16(10), 221; https://doi.org/10.3390/microbiolres16100221 - 9 Oct 2025

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Abstract

The emergence of Candida auris as a disheartening fungal pathogen in healthcare settings has prompted urgent re-evaluation of containment and mitigation strategies. This review critically examines the biological persistence, environmental adaptability, and resistance to standard antifungal therapies of the pathogen, particularly regions with [...] Read more.

The emergence of Candida auris as a disheartening fungal pathogen in healthcare settings has prompted urgent re-evaluation of containment and mitigation strategies. This review critically examines the biological persistence, environmental adaptability, and resistance to standard antifungal therapies of the pathogen, particularly regions with limited surveillance infrastructure. Based on regional experiences, such as those in Saudi Arabia and the Middle East in general, the study reveals systemic weaknesses in diagnosis, reporting, and environmental sanitation. Special consideration is paid to the combination of new disinfection technologies, including ultraviolet irradiation systems and hydrogen peroxide vaporisation, with institutional behaviour change strategies. This discussion shows the importance of synchronising technological development with frequent employee contributions and cross-functional planning. It also encourages the international standardisation of diagnostic platforms and the launch of real-time genomic surveillance to reveal evolutionary trends. Finally, the findings justify the shift towards proactive models of infection control that are founded on the resilience of systems and the agility of institutions. This paper is a synthesis of epidemiological patterns, decontamination strategies and behavioural knowledge to contribute to an emerging body of knowledge that can help to fortify healthcare settings against current fungal threats. Full article

(This article belongs to the Special Issue Medically Relevant Fungi: Virulence Factors, and New Diagnostic and Treatment Approaches)

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17 pages, 5555 KB

Open AccessArticle

Isolation/Characterization of Colletotrichum gloeosporioides from Tea and MeJA-Induced Antioxidant Defenses

by Chunju Peng, Yu Wang, Xuan Zhou, Shifu Ma, Zhiguo Shan, Shuai Wan, Zekun Xue, Huiling Mei, Yan Tang, Shujing Liu, Rui Han, Xinghui Li and Guanghui Zeng

Microbiol. Res. 2025, 16(10), 220; https://doi.org/10.3390/microbiolres16100220 - 8 Oct 2025

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Abstract

Anthracnose is a leaf fungal disease caused by multiple Colletotrichum species. Currently, the predominant deployment of chemical agents for anthracnose control increases ecological pollution risks and potential food safety concerns. The comprehension of the pathogenic mechanism and physicochemical properties of anthracnose is, therefore, [...] Read more.

Anthracnose is a leaf fungal disease caused by multiple Colletotrichum species. Currently, the predominant deployment of chemical agents for anthracnose control increases ecological pollution risks and potential food safety concerns. The comprehension of the pathogenic mechanism and physicochemical properties of anthracnose is, therefore, essential for effective prevention and control. In this study, the pathogenic strain (pathogen) was isolated from the infected tea plant (Camellia sinensis) leaves and was identified as Colletotrichum gloeosporioides based on microscope observations and gene sequences. This fungus exhibited optimal growth at 28 °C and a pH of 6, with a lethal temperature threshold of 53 °C on PDA plate medium. The 80% tea saponin and 10% polymycin B could effectively inhibit its mycelium growth. Notably, the 10% polyoxin B exhibits a stronger inhibitory effect with an EC₅₀ value of 1.07 mg mL⁻¹. Following infection with Colletotrichum gloeosporioides, the resistant cultivar ‘Zhongcha 108’ exhibited higher levels of H₂O₂ and O₂⁻ than the susceptible ‘Longjing 43’, with later symptom onset and slower disease progression. Although the exogenous treatment of methyl jasmonate (MeJA) did not inhibit C. gloeosporioides directly, it significantly reduced lesion areas in ‘Longjing 43’ leaves caused by C. gloeosporioides. This treatment increased peroxidase and superoxide dismutase activities, but limited malondialdehyde content, thereby enhancing ‘Longjing 43’ resistance to the pathogen. The findings provide scientific guidance for the anthracnose prevention and control in tea gardens. Full article

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19 pages, 3831 KB

Open AccessArticle

Phenotypic, Pathogenic, and Genetic Diversity of Botrytis cinerea Isolates from Moroccan Vineyards

by Faical Aoujil, Chaimae El Ghdaich, Imane Hourmatallah, Hiba Yahyaoui, Majida Hafidi, Aziz Aziz and Khaoula Habbadi

Microbiol. Res. 2025, 16(10), 219; https://doi.org/10.3390/microbiolres16100219 - 5 Oct 2025

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Abstract

Gray mold, caused by Botrytis cinerea Pers. Fr. (teleomorph: Botryotinia fuckeliana), is a major disease affecting Moroccan vineyards. However, limited information is available on the natural populations of this pathogen. In this study, 82 single-spore isolates collected from vineyards in two major [...] Read more.

Gray mold, caused by Botrytis cinerea Pers. Fr. (teleomorph: Botryotinia fuckeliana), is a major disease affecting Moroccan vineyards. However, limited information is available on the natural populations of this pathogen. In this study, 82 single-spore isolates collected from vineyards in two major wine-growing regions were evaluated for phenotypic, physiological, and molecular variability. The isolates exhibited differences in morphotypes, conidial size, and sclerotia production on PDA medium. Temperature significantly affected mycelial growth rate (mm d⁻¹). All isolates were virulent on grapevine leaves, showing varying levels of aggressiveness. Among the representative isolates, 20 were heterothallic and 2 were homothallic. Mating-type analysis revealed that 12% belonged to MAT1-1 and 75% to MAT1-2. Transposable element genotyping showed that the population was composed of 41.7% transposa, 29.2% vacuma, 16.7% Flipper-only, and 12.5% Boty-only. This work represents the first report on genotypic variation in B. cinerea populations from Moroccan vineyards. The findings provide new insights into the morphenotypic and genetic diversity of the pathogen and may support the development of improved strategies for disease management. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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13 pages, 1261 KB

Open AccessArticle

Influence of Milking Process and Production System on Raw Goat Milk Bacteriome

by Ezquibel Montesinos Rivera, Estela Garza Brenner, Pascuala Ambriz Morales, Williams Arellano Vera, Rogelio de J. Treviño-Rangel and Ana María Sifuentes Rincón

Microbiol. Res. 2025, 16(10), 218; https://doi.org/10.3390/microbiolres16100218 - 4 Oct 2025

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Abstract

The aim of this study was to compare, during milking, the bacteriomes of goat milk from farms in Mexico representing traditional and semi-intensive production systems. Metagenomic DNA was isolated from pooled milk samples collected at different milking stages, and following 16S rRNA-targeted sequencing, [...] Read more.

The aim of this study was to compare, during milking, the bacteriomes of goat milk from farms in Mexico representing traditional and semi-intensive production systems. Metagenomic DNA was isolated from pooled milk samples collected at different milking stages, and following 16S rRNA-targeted sequencing, alpha (Shannon H’ and Simpson D) and beta (Bray–Curtis) diversity indices were calculated. Within the semi-intensive system, fore-stripping showed lower diversity (H’ = 1.5 vs. H’ = 4.0) but greater evenness (D = 0.5 vs. D = 0.8) than the milking stage. In contrast, no differences between stages in the traditional system were observed. The Bray–Curtis index revealed that the use of the semi-intensive system explained 99.4% of the variability, while the traditional system accounted for only 0.5%. In the semi-intensive system, fore-stripping was dominated by Mesoplasma (51.9%) and Staphylococcus (42.1%), whereas Enterococcus (27.2%) and Lactococcus (18.5%) prevailed during milking. Meanwhile, in the traditional system, Pseudomonas (46.9% and 22.7) and Lactococcus (22.7% and 29.2%) predominated in both stages. Management practices strongly influence the microbiological profile of milk, leading to changes in not only the diversity and abundance of pathogenic bacteria but also in the presence of beneficial lactic acid bacteria and, hence, the overall expected milk quality. Full article

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16 pages, 1782 KB

Open AccessArticle

Fungal Functional Level to Describe Soil Fungal Composition at Mediterranean Vineyards

by Yasmin Piñuela, María Hernández, Iván Escudero, Peter Sisseck and Jaime Olaizola

Microbiol. Res. 2025, 16(10), 217; https://doi.org/10.3390/microbiolres16100217 - 2 Oct 2025

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Abstract

Understanding the soil fungal community in vineyards sheds light on the interactions between plants and their associated microorganisms. For example, identifying arbuscular mycorrhizal fungi (AMF), which are beneficial to grapevine growth, is a good indicator of soil health. In contrast, other fungi, such [...] Read more.

Understanding the soil fungal community in vineyards sheds light on the interactions between plants and their associated microorganisms. For example, identifying arbuscular mycorrhizal fungi (AMF), which are beneficial to grapevine growth, is a good indicator of soil health. In contrast, other fungi, such as the pathogen group, can be detrimental to vine growth. The present study aimed to characterize the soil fungal community and the fungal diversity present at six Mediterranean vineyards located in Burgos (Spain), delving into fungal functional guilds and focusing on AMF and pathogenic fungal groups. The fungal structure was investigated using DNA metabarcoding in three soil samples taken from each vineyard, and differences in the abundance of functional guilds were assessed. Similar soil fungal community structures were observed among soil sample repetitions within vineyards. In contrast, adjacent vineyards presented differences in their microbial composition. Saprophytes followed by pathogens were the dominant fungal functional guilds across all vineyards. However, no differences in the relative abundance of the different fungal functional groups were observed among sites. The vineyard with the highest relative abundance of AMF (0.5%) also had the lowest pathogen relative abundance from all the sites (29.76%). Also, sites presenting a high relative abundance of pathogens in soil (>35%) had a low relative abundance of AMF (<0.05%). Our results suggest that the fungal community is affected by the intrinsic properties of the soil and the characteristics of each vineyard’s microsite over the effect of the geographical proximity. In addition, to improve our understanding of the soil microbial ecology, we highlight the necessity of prospecting soil fungal analyses into functional groups, interpreting diversity results within taxonomic groups alongside the total abundance of target groups/species. Full article

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14 pages, 279 KB

Open AccessArticle

Molecular Epidemiology of Different Bacterial Pathogens and Their Antimicrobial Resistance Genes Among Patients Suffering from Surgical Site Infections in Lebanon

by Inass Kawtharani, Ghassan Ghssein, Ola Srour, Abdul Amir Chaaban and Pascale Salameh

Microbiol. Res. 2025, 16(10), 216; https://doi.org/10.3390/microbiolres16100216 - 1 Oct 2025

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Abstract

Background: Antimicrobial resistance (AMR) is a major global health threat, particularly in surgical site infections (SSIs), where multidrug-resistant (MDR) pathogens complicate treatment. Objective: This study aimed to identify antimicrobial resistance genes and assess their prevalence in bacterial species causing SSIs in Lebanon. Materials [...] Read more.

Background: Antimicrobial resistance (AMR) is a major global health threat, particularly in surgical site infections (SSIs), where multidrug-resistant (MDR) pathogens complicate treatment. Objective: This study aimed to identify antimicrobial resistance genes and assess their prevalence in bacterial species causing SSIs in Lebanon. Materials and Methods: The present research is a multicenter and prospective study that included patients who developed SSIs after surgery in seven hospitals, within the period of January 2024–September 2024. Bacterial isolates from wound swabs or tissue samples were identified using standard microbiological methods. Antimicrobial susceptibility was tested by disk diffusion, and resistance genes were detected by PCR. Data were analyzed using Statistical Package for the Social Sciences (SPSS). Results: Among 6933 surgical patients, 63 developed SSIs (0.91%; 95% CI [0.70–1.15]). Gram-negative bacteria predominated (73%), mainly Escherichia coli and Pseudomonas aeruginosa, while Gram-positive isolates accounted for 27%, mostly Staphylococcus aureus. MDR was observed in 71% of Gram-positive and 61% of Gram-negative isolates. The most frequent genes were mecA in S. aureus (100%) and coagulase-negative staphylococci (83.3%); bla_CTX-M in E. coli, Klebsiella pneumoniae, and Enterobacter cloacae (100%); and bla_NDM in E. cloacae (100%) and Acinetobacter baumannii (60%). bla_KPC was less common, and no isolates carried Imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), and Oxacillinase-48-like β-lactamase (OXA-48). Conclusions: This study highlights the high prevalence of antibiotic resistance in agents causing SSIs in Lebanese hospitals. Resistance genes, particularly mecA, bla_CTX-M, and blaNDM, were highly prevalent in SSI pathogens, underscoring the urgent need for surveillance and judicious antibiotic use in Lebanese hospitals. Full article

(This article belongs to the Topic Multidrug Resistance Across Pathogens: Fungi, Bacteria, Parasites, and Viruses)

12 pages, 486 KB

Open AccessArticle

Research on the Influence of Enterobius vermicularis on the Composition and Quality of the Intestinal Microbiota, and the Susceptibility to Co-Infections

by Eleonora Kaneva, Rumen Harizanov, Maria Pavlova, Desislava Velcheva, Nina Tsvetkova, Aleksandra Ivanova, Mihaela Videnova, Raina Borisova, Ivailo Alexiev and Reneta Dimitrova

Microbiol. Res. 2025, 16(10), 215; https://doi.org/10.3390/microbiolres16100215 - 30 Sep 2025

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Abstract

The present study examined the presence of concomitant intestinal parasites and bacteria in individuals infected with Enterobius vermicularis in Bulgaria, and analyzed its effects on the intestinal microbiome and the risk of co-infection. Fecal samples from people with and without (control group) enterobiasis [...] Read more.

The present study examined the presence of concomitant intestinal parasites and bacteria in individuals infected with Enterobius vermicularis in Bulgaria, and analyzed its effects on the intestinal microbiome and the risk of co-infection. Fecal samples from people with and without (control group) enterobiasis were tested for the presence of concomitant bacterial infection. The results were compared to find out about the intestinal microbiome in these groups. The microbiological examination of the control group showed that 8.3% had only conditionally pathogenic flora. However, in individuals with enterobiasis, 56% had normal intestinal bacterial flora, but 46% had disturbed microbiota: 7% were carriers of pathogenic intestinal bacteria and 24% had opportunistic pathogens. The most prevalent were Klebsiella pneumoniae (49%), followed by Enterobacter spp. (22%), and Proteus mirabilis (12.2%). Our study is the first in the country to investigate the impact of E. vermicularis infection on the composition and quality of the gut microbiome, as well as the potential for co-infections with pathogenic gut bacteria. Although our findings are preliminary, they suggest that this nematode may significantly contribute to a predisposition for dysbiosis or the onset of secondary bacterial infections. Full article

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16 pages, 3572 KB

Open AccessArticle

Genome-Wide Analysis and Expression Profiling of the Cellulase Genes in Aspergillus oryzae

by Danni Hu, Ruoyu Zhao, Yingxu Lin and Chunmiao Jiang

Microbiol. Res. 2025, 16(10), 214; https://doi.org/10.3390/microbiolres16100214 - 26 Sep 2025

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Abstract

One of the critical steps in lignocellulosic deconstruction is the hydrolysis of cellulose by cellulases. Aspergillus oryzae can produce and secrete a large amount of various extracellular enzymes, including cellulases. However, due to the lack of a comprehensive characterization of the cellulase genes [...] Read more.

One of the critical steps in lignocellulosic deconstruction is the hydrolysis of cellulose by cellulases. Aspergillus oryzae can produce and secrete a large amount of various extracellular enzymes, including cellulases. However, due to the lack of a comprehensive characterization of the cellulase genes in A. oryzae, the development and application of A. oryzae cellulase are greatly limited. In this study, a total of 219 glycosyl hydrolase genes were systematically identified from the A. oryzae 3.042 genome and classified into 40 glycosyl hydrolase families. Among these glycosyl hydrolase genes, 26 genes encoding the cellulases of endoglucanase, exoglucanase, and β-glucosidase were identified and functionally characterized. The chromosome localizations, gene structures, functional domains, and subcellular localizations of these 26 cellulases were analyzed by bioinformatics. In addition, analysis of the expression patterns revealed that the expression of A. oryzae cellulase genes was time-specific, and most of the cellulase genes were inhibited under low- and high-temperature stress and high salt stress, which had important guiding significance for understanding the transcription patterns of A. oryzae cellulase genes. These findings lay a foundation for our subsequent modification of cellulase activity to realize the industrial applications of A. oryzae cellulase genes in cellulose biorefineries. Full article

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18 pages, 3054 KB

Open AccessArticle

Altitudinal Gradient Drives Rhizosphere Microbial Structure and Functional Potential in Prickly Pear Cactus (Opuntia ficus-indica L.)

by Lorena Jacqueline Gómez-Godínez, José Luis Aguirre-Noyola, Carlos Hugo Avendaño-Arrazate, Sergio de los Santos-Villalobos, Magali Ruiz-Rivas, Ramón Ignacio Arteaga-Garibay and José Martín Ruvalcaba-Gómez

Microbiol. Res. 2025, 16(10), 213; https://doi.org/10.3390/microbiolres16100213 - 26 Sep 2025

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Abstract

The prickly pear cactus (Opuntia ficus-indica L.) is an emblematic crop for Mexico’s economy, gastronomy, and culture. Microbial communities play an important role in the health, development, and productivity of crops. This study used 16S rRNA high-throughput sequencing and bioinformatic analyses to [...] Read more.

The prickly pear cactus (Opuntia ficus-indica L.) is an emblematic crop for Mexico’s economy, gastronomy, and culture. Microbial communities play an important role in the health, development, and productivity of crops. This study used 16S rRNA high-throughput sequencing and bioinformatic analyses to evaluate the rhizosphere microbiome of prickly pear cactus across an altitudinal gradient in Milpa Alta (Mexico). A microbial core consisting of Bacillus, Acidibacter, and Sphingomonas was detected, reflecting strong co-adaptation between plants and soil microorganisms under different agroecosystems. However, in the lower-altitude zones, Conexibacter, Agromyces, Domibacillus, Pedomicrobium, and Rokubacteriales predominated, which are associated with humid environments and high organic matter content. In contrast, in the middle-altitude zones, Acidothermus, Gemmatimonas, Mesorhizobium, and Pseudoxanthomonas were enriched, which are involved in carbon and nitrogen cycles. Higher-altitude zones exhibited greater bacterial specialization, with genera adapted to more extreme conditions such as Halocella, Solirubrobacter, Rhodomicrobium, Phenylobacterium, Roseomonas, Pseudarthrobacter, Crossiella, Aquicella, and others. Overall, our data show that altitude acts as an ecological filter structuring soil microbial communities associated with prickly pear cactus, influencing the diversity and functional potential. This study on microbial diversity not only provides insights into the health of the agroecosystem but also represents a valuable source of microorganisms with functional potential for sustainable agriculture. Full article

(This article belongs to the Topic New Challenges on Plant–Microbe Interactions)

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13 pages, 3043 KB

Open AccessArticle

Phylogenetic Incongruence of Cyclic di-GMP-Activated Glycosyltransferase nfrB with 16S rRNA Gene Tree Reflects In Silico-Predicted Protein Structural Divergence in Diaphorobacter nitroreducens Isolated from Estero de Paco, Manila, Philippines

by Ram Julius L. Marababol and Windell L. Rivera

Microbiol. Res. 2025, 16(10), 212; https://doi.org/10.3390/microbiolres16100212 - 26 Sep 2025

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Abstract

Diaphorobacter nitroreducens is a Gram-negative bacterium ubiquitously found in wastewater, recognized for its ecological adaptability and potential applications in environmental, biomedical, and industrial processes. Central to its adaptability is the nfrB gene, which encodes a cyclic di-3′,5′-guanylate (c-di-GMP)-activated glycosyltransferase. This enzyme facilitates the [...] Read more.

Diaphorobacter nitroreducens is a Gram-negative bacterium ubiquitously found in wastewater, recognized for its ecological adaptability and potential applications in environmental, biomedical, and industrial processes. Central to its adaptability is the nfrB gene, which encodes a cyclic di-3′,5′-guanylate (c-di-GMP)-activated glycosyltransferase. This enzyme facilitates the secretion of biofilm-associated extracellular polymeric substances (EPS), essential for its survival and functionality in diverse environments. Using complete EMJH media as a selective medium, D. nitroreducens was successfully isolated from soil and water samples from Estero de Paco, Manila, Philippines, enabling downstream analyses of its nfrB gene. Phylogenetic analyses revealed that the nfrB gene tree deviates significantly from the canonical 16S rRNA gene tree, with D. nitroreducens clustering alongside members of the Enterobacteriaceae family. This deviation suggests the potential influence of horizontal gene transfer, adaptive evolution, or lineage-specific pressures on nfrB evolution. Structural analysis of NfrB through Alphafold 3 prediction demonstrated a conserved N-terminal region across taxa, except for the outgroup Zymomonas mobilis. Conversely, the C-terminal region, housing the catalytic domain, showed considerable diversity, reflecting adaptive modifications across bacterial lineages. Despite this variability, the putative binding site for cyclic di-3′,5′-guanylate remained conserved, indicating a balance between functional conservation and adaptive diversification. These findings not only deepen the existing understanding of bacterial signaling and glycosylation mechanisms but also provide insights into the evolutionary dynamics of glycosyltransferases. Furthermore, the study underscores the potential of NfrB as a target for innovative applications, including the design of novel biocatalysts and the development of informed strategies for bacterial management in environmental, industrial, and biotechnological contexts. Full article

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17 pages, 2778 KB

Open AccessArticle

Bacillus Probiotic Strains Induce Gonadal Maturation and Sex Differentiation in Red Abalone Haliotis rufescens Using a Plant-Based Diet

by Jorge Olmos, Manuel Acosta-Ruiz, Fabiola Lafarga-De la Cruz and Jeremie Bauer

Microbiol. Res. 2025, 16(10), 211; https://doi.org/10.3390/microbiolres16100211 - 24 Sep 2025

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Abstract

This study examined the effects of Bacillus probiotic strains on red abalone Haliotis rufescens reproductive performance. We supplemented plant- and fish-based feeds and compared them to fresh giant kelp Macrocystis pyrifera as a control diet. Over 180 days, abalone fed the plant–probiotic diet [...] Read more.

This study examined the effects of Bacillus probiotic strains on red abalone Haliotis rufescens reproductive performance. We supplemented plant- and fish-based feeds and compared them to fresh giant kelp Macrocystis pyrifera as a control diet. Over 180 days, abalone fed the plant–probiotic diet reached higher female gonadal maturation, with 56% of females attaining the maximum Visual Gonad Index (VGI 3). Additionally, plant-based treatment showed a female-biased sex ratio (1.5:1 female-to-male ratio, F:M) compared with the kelp control treatment (0.8:1 F:M). These results suggest that probiotics can improve nutrient utilization from soybean meal and may enhance the bioavailability of phytoestrogens and other bioactive compounds, contributing to reproductive outcomes. Although the mechanisms remain to be confirmed, this approach provides a promising strategy to reduce reliance on fishmeal and wild macroalgae while supporting faster reproductive cycles in abalone aquaculture. Future research should focus on biochemical validation, molecular pathways, and multigenerational trials to ensure the long-term safety and sustainability of probiotic–plant-based feeds. Full article

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17 pages, 2176 KB

Open AccessCommunication

Gut Microbiome Analysis Reveals Core Microbiota Variation Among Allopatric Populations of the Commercially Important Euryhaline Cichlid Etroplus suratensis

by Jilu Alphonsa Jose, Anoop Alex and Siby Philip

Microbiol. Res. 2025, 16(10), 210; https://doi.org/10.3390/microbiolres16100210 - 23 Sep 2025

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Abstract

The gut microbiome plays a critical role in host physiology and adaptation, shaped by both intrinsic host factors and extrinsic environmental conditions. In this study, we investigated the influence of habitat type and geographical isolation on gut microbial communities in habitat-isolated populations of [...] Read more.

The gut microbiome plays a critical role in host physiology and adaptation, shaped by both intrinsic host factors and extrinsic environmental conditions. In this study, we investigated the influence of habitat type and geographical isolation on gut microbial communities in habitat-isolated populations of the euryhaline cichlid Etroplus suratensis, which inhabit freshwater and brackish water environments. Using 16S rRNA gene amplicon sequencing, we compared microbial assemblages in fish guts and their corresponding habitats to assess patterns of community divergence. Alpha and beta diversity analyses revealed significant differences in microbial composition between gut and water samples, with limited overlap, particularly in brackish water, indicating strong host-mediated filtering of environmental microbiota. Notably, brackish and freshwater habitats harbored 2244 and 3136 unique water-associated taxa, respectively, while only 36 and 426 taxa were shared between water and gut in each habitat. Despite habitat divergence, 59 microbial taxa were consistently shared across gut samples from both populations, indicating the existence of a conserved core microbiome that likely fulfills essential functional roles. These findings support the notion that the fish gut serves as a selective ecological niche, enabling the persistence of functionally relevant microbes while restricting the entry of environmental transients. Moreover, the observed divergence in gut microbiota across habitats, coupled with a shared core, highlights the interplay between local adaptation and conserved host–microbe associations, with potential implications for understanding microbial contributions to vertebrate ecological diversification and allopatric speciation. Full article

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