Journal of Advances in Microbiology

Soil Microbiome Engineering in Sustainable Agriculture: A Comprehensive Review

Abhishek Sharma — 2025-12-02

Soil microbiome engineering, a frontier within sustainable agriculture, involves the manipulation as well as stewardship of soil microbial communities to improve crop productivity, restore soil health and address climate-related challenges. This review critically synthesizes recent advances in microbial inoculants, as well as engineered synthetic communities with host-mediated genetic strategies aimed at improving plant performance in fluctuating environments. Recent developments in synthetic microbial consortia design demonstrate enhanced colonization efficiency and synergistic interactions that surpass single-strain inoculants, multi-strain communities showing yield improvements across diverse agroecosystems. Special emphasis is placed on mechanisms, cost–benefit considerations, and case studies demonstrating agronomic and ecological potential across different cropping systems. This discussion also covers environmental, economic, policy factors plus opportunities and lasting issues like biosafety fears, rules, farmer uptake. Soil microbiome engineering combines perceptions from multi-omics, digital technologies, and synthetic biology providing scalable solutions for nutrient management, disease suppression, and stress resilience. Key bottlenecks are field-to-lab translation gaps, economic scalability, identified in this type of review. Academics, regulators, and industry are guided toward responsibly embedding microbiome engineering into global food systems with future research pathways that are also outlined.

Bioconversion of Agricultural Residues into Nutrient-Rich Compost: A Sustainable Approach to Waste Valorization

Aiswarya Prasanth — 2025-12-03

The rapid expansion of agro-industrial production has generated large volumes of lignocellulosic agricultural residues, many of which remain underutilized or are burned, causing nutrient loss and environmental pollution. Composting provides a sustainable pathway to convert these wastes into valuable organic amendments, yet the inherent resistance of plant structural polymers often slows decomposition and reduces compost quality. Emerging research highlights the potential of microbial consortia, combining lignocellulolytic, thermotolerant and nutrient-mobilizing microorganisms to substantially enhance biomass breakdown and accelerate compost maturation. These tailored communities improve organic matter transformation and humus formation by coordinating complementary metabolic activities under optimized composting conditions. This review synthesizes recent advances in consortium-based composting and outlines their advantages over conventional methods. Overall, the strategic use of microbial consortia offers a cost-effective and environmentally sound approach for converting agricultural residues into high-quality compost, strengthening soil fertility and supporting sustainable land management.

Comparative Evaluation of Bacteriophage Plaque Formation on Different Culture Media

Foziya Farzeen Khan — 2025-12-03

Bacteriophages are bacterial viruses with promising applications in microbial biocontrol and antimicrobial therapy. The efficiency of bacteriophage isolation and visualization can depend on the type of culture medium used for plaque formation. This study provides a comparative assessment that helps standardize plaque assays for routine phage screening. This study aimed to isolate and compare bacteriophage recovery from different agar media—Luria–Bertani Agar (LBA), Nutrient Agar (NA), Eosin Methylene Blue (EMB) Agar, and MacConkey Agar—using Escherichia coli as a host. Sewage samples from livestock facilities were processed and enriched using the double agar layer (DAL) method. Distinct plaques appeared after 18–24 hours of incubation at 37 °C, varying in size and clarity across media types. The highest phage titer and clearest plaques were obtained on LBA (4.7 × 10³ PFU/mL), followed by EMB (4.1 × 10³ PFU/mL), NA (3.6 × 10³ PFU/mL), and MacConkey Agar (3.2 × 10³ PFU/mL). LBA supported larger and more distinct plaques, while MacConkey medium produced smaller, turbid plaques. These results demonstrate that media composition significantly influences bacteriophage plaque morphology and enumeration, with LBA being the most effective for phage isolation and visualization against E. coli. Taken together, these results underscore the importance of carefully selecting culture media when designing phage isolation workflows, particularly in laboratories working on phage therapy development and environmental surveillance of E. coli phages.

Effect of Storage Period on Sensory Attributes of Millet Based Fortified Spread to Mitigate Hidden Hunger

Anjali Yadav — 2025-11-19

The study was carried out for determining of the effect of storage period on sensory characteristics of spread formulated by millets (finger and barnyard) and other ingredients (sweet potato, sesame seeds and anjeer). Among the tested formulations, the spread containing 50 g finger millet, 38 g barnyard millet, 5 g sweet potato, 2 g sesame seeds, and 5 g anjeer received the highest overall acceptability from panellists. Samples were packed in airtight containers and analysed at 0, 3, 6, and 9 days of storage to assess changes in quality parameters. By day 9 of storage, a slight increase in moisture content was observed in all millet spreads. The control sample exhibited the highest moisture content (58.85–62.00%), whereas treatment T2 showed the lowest (50.07–53.99%). The total bacterial count (TBC) increased from 0.53 × 10² CFU/g on day 3 to 2.46 × 10⁴ CFU/g by day 9. The total mold count (TMC) remained below detectable levels throughout the storage period. The result of present investigation suggested that millet spread could be kept in glass jar air tight container at room temperature for a period of 9 days without experience and quality deterioration.

Foliar Nitrogen Fixers on Knol Khol: Differential Isolation, Characterization and Biofertilizer Potential of Azotobacter and Azospirillum

Dayashankar Baghel — 2025-11-19

The rising need for sustainable agricultural practices, especially in non-leguminous vegetable production, necessitates the exploration of alternative nitrogen sources like plant-associated nitrogen-fixing bacteria. This study aimed to isolate, characterize and evaluate native foliar nitrogen-fixing bacteria, Azotobacter and Azospirillum, from knol khol (Brassica oleracea var. gongylodes) leaves collected across diverse farming regions of Chhattisgarh, India, to assess their potential as foliar biofertilizers. Twelve leaf samples were collected from fields representing varied cultivation practices, including chemical application. Foliar Azotobacter was isolated from 10 samples but could not be recovered from fields associated with heavy pesticide use, whereas Azospirillum was successfully isolated from all 12 samples, suggesting its potential endophytic nature and greater resilience to chemical stress. All isolates were confirmed as Gram-negative with variable biochemical profiles. Nitrogen-fixing efficiency varied significantly, with the most efficient Azotobacter isolate (Kk-Azot-6) fixing 10.58 mg N g-¹ sucrose and the top Azospirillum isolate (Kk-Azos-10) exhibiting a higher efficiency of 15.56 mg N g-¹ malate. The superior nitrogen-fixing potential and differential stress tolerance observed, particularly in Azospirillum, emphasize the significant ecological role of these bacteria on aerial plant surfaces and their strong candidacy for developing effective foliar biofertilizers for sustainable and eco-friendly crop production.

Detection and Antibiogram of Staphylococcus spp. & Vibrio spp. Isolated from Fresh Fruit Juices and Sauces Collected from Cafes and Restaurants in Dhaka City, Bangladesh

Md. Hossain — 2025-11-21

Aims: This study aim to assess the microbial status of fruit juices and sauces from cafes and restaurants in Dhaka city, Bangladesh.

Study Design: Juice and sauce samples were collected from different areas of Dhaka city under aseptic conditions. The samples were diluted to get distinct colonies and were cultivated on nutrient agar to get isolated colonies. The colony was inoculated on selective media to identify its traits. Then the isolated colonies were identified by biochemical tests, and their drug susceptibility was investigated.

Place and Duration of Study: The study was carried out in Dhaka city in Bangladesh between June 2023 to October 2023.

Methodology: Fruit juice and sauce samples were collected by aseptic technique. The samples were transported to the laboratory within one hour. Several diluted samples were inoculated on a nutrient agar plate to get an isolated colony. The isolated colonies were cultivated on Mannitol Salt Agar (MSA) agar and Thiosulfate Citrate Bile Salts Sucrose (TCBS) agar media. The colony morphology was investigated. Gram staining and biochemical tests were conducted to identify the specific organisms. Finally, the antibiotic susceptibility tests were done by the Kirby-Bauer disc diffusion method.

Results: A total of 42 samples, including 6 different fruit juices and 3 sauces, were collected for the isolation of organisms, and the selective media were used to identify Staphylococcus spp. and Vibrio spp. Gram staining and biochemical tests indicate the presence of Staphylococcus spp. and Vibrio spp.

Out of 42 samples, 21 samples were Staphylococcus spp., and 3 samples were Vibrio spp. Drug susceptibility was investigated by the disc diffusion method. Two strains of Staphylococcus spp were amoxicillin and amikacin-resistant. One strain of Vibrio spp. was ceftriaxone-resistant.

Conclusion: Fresh fruit juices and sauces contain food-borne pathogens, which is alarming for human health. The result revealed that about 57% of samples were contaminated by Staphylococcus spp. (50%) and Vibrio spp. (7%). Some of the organisms were drug-resistant. Consciousness and proper education, especially on microbes, need to overcome the threat of pathogen spread.

Antibacterial and Antioxidant Activities of Aqueous and Hydroethanolic Extracts of Tetracera potatoria Afzel Ex G. Don Leaves

Raoul Ampa — 2025-11-21

The aim of this study is to evaluate the antibacterial and antioxidant activities of aqueous and hydroethanolic extracts of Tetracera potatoria leaves. Polyphenol, flavonoid, and total tannin contents were assessed by spectrophotometry in the aqueous and hydroethanolic extracts. Antibacterial and antioxidant activities were evaluated using solid medium diffusion and liquid medium dilution methods, and by DPPH and FRAP assays, respectively. Both extracts showed high contents of polyphenols (350 and 600 mg GAE/g extract), flavonoids (1000 and 2000 mg QE/g extract), and tannins (700 and 400 mg GAE/g extract). Sensitivity tests indicated that both extracts exhibit antibacterial activity with inhibition diameters ranging from 11 to 15 mm. Staphylococcus aureus, Salmonella sp., and Escherichia coli were more sensitive to the extracts compared to Pseudomonas aeruginosa.

These two extracts strongly inhibit the growth of Salmonella sp., with minimum bactericidal concentrations (MBC) of 200 mg/mL compared to those of Staphylococcus aureus and Escherichia coli, which have minimum inhibitory concentrations (MIC) of 200 mg/mL.

DPPH and FRAP tests revealed that both extracts possess remarkable antioxidant activity with IC50 values of 1.92 and 3.3 mg/mL, and iron-reducing capacity with IC50 values of 5.71 and 5.26mg/mL. The observed antibacterial and antioxidant activities can be attributed to polyphenols, flavonoids, and tannins. These results may justify the use of these leaves in traditional medicine.

Cloning and Expression of ORF 2 Protein of PCV2 in Pichia Pastoris

N. Sweetline Anne — 2025-11-27

Porcine circovirus type 2 (PCV2) is a major pathogen responsible for post-weaning multisystemic wasting syndrome in pigs, causing significant economic losses in the swine industry. The ORF2 gene of PCV2 encodes the capsid (Cap) protein, the primary immunogenic component and a key target for vaccine development and serological diagnostics. In this study, the ORF2 gene was cloned and expressed in Pichia pastoris X-33 to establish a eukaryotic expression system for the recombinant Cap protein. Codon optimization was employed to enhance expression efficiency in the yeast host. Successful cloning was confirmed by restriction analysis and PCR, while expression of recombinant Cap protein was verified by SDS-PAGE and western blotting. These results highlight P. pastoris as a robust platform for the large-scale production of PCV2 Cap protein, providing a foundation for future subunit vaccine development and improved diagnostic strategies against PCV2 infection.

Plant Growth-promoting Potentials of Mycoendophytes Associated with Medicinal Herb Argemone mexicana L.

Medha Timmanna Bhat — 2025-11-27

Aims: Argemone mexicana L., a ubiquitous, medicinally important herb that possesses therapeutic properties used in traditional medicine. It hosts a diverse species of mycoendophytes. Their use in promoting plant development has not yet been investigated. Hence, this study aimed to investigate the potentials of the mycoendophytes of A. mexicana as plant growth promoters.

Study Design: The experimental design included the analysis of plant growth-promoting properties of selected mycoendophytes from the plant Argemone mexicana through different qualitative and quantitative assays.

Place and Duration of Study: Department of Microbiology, Davangere University, Davangere, Karnataka, from November 2023 to January 2025.

Methodology: Different mycoendophytes isolated from healthy tissues of Argemone mexicana, the Aspergillus luchuensis (DUMB 210 and DUMB 222), Penicillium dierckxii (DUMB 208), and Penicillium restrictum (DUMB 211) were selected based on their antimicrobial properties. They were examined for their abilities to solubilize the nutrients through plate assays and Solubilization Index (SI) was calculated as ratio between diameter of zone of clearance and colony diameter. The Indole-3-acetic acid (IAA) and siderophore production were detected using Salkowski’s reagent method and on Chrome Azurol S (CAS) agar medium respectively. Ammonia secretion was analysed using the Nessler’s reagent, and the nitrogen fixation was determined in nitrogen-free media. The effects of fungal seed treatment on seed germination and seedling vigour of sorghum and green gram were evaluated by rolled paper-towel method.

Results: Phosphate, potassium, and zinc solubilization potentials were exhibited by all the four mycoendophytes. The isolates of Aspergillus luchuensis (DUMB 210 and DUMB 222) displayed greater potassium and zinc solubilization with SI of 1.36±0.02 and 1.61±0.01 for potassium, and SI of 2.58±0.11 and 2.39±0.03 for zinc respectively. Further, they were also highly potential producers of IAA with 139.47±3.40 µg/ml and 112.22±3.86 µg/ml of culture filtrate. The Penicillium spp. were not producing siderophores. All the isolates showed maximum ammonia production and also capable of nitrogen fixation. The fungal culture filtrate and the fungal biomass of P. restrictum (DUMB 211) significantly improved both sorghum and green gram seedling vigour and biomass. Thereby, the P. restrictum (DUMB 211) was the potential fungal isolate to promote early seedlings growth.

Conclusion: The potential of mycoendophytes from A. mexicana was established in plant growth promotion. These fungi may be used for seed biopriming in sustainable agriculture.

The Impact of Mutations in the Pore-Forming Cytotoxins NheA and NheB of Bacillus cereus Isolated from four Traditional Fermented Beverages

Christian Aimé Kayath — 2025-11-29

Bacillus cereus is commonly associated with foodborne illnesses but also plays a significant role in food and beverage fermentations. Mutations in the non-hemolytic enterotoxin (Nhe) genes, which encode the NheA, NheB, and NheC components, can have significant functional consequences. This study aims to determine whether hemolytic enterotoxin Hbl, non-hemolytic enterotoxin (NheA, NheB, and NheC), and CytK components contain mutations that could alter the 3D structure of these proteins. Using microbiological and molecular techniques, including 16S rRNA analysis, 300 isolates were identified as B. cereus, with 11% (34/300) confirmed through NCBI accession, demonstrating its ubiquity. Genotypic and phenotypic analyses revealed strains with enzymatic activities, suggesting potential benefits in fermentation processes. Strains were also tested for the presence of the Hbl, Nhe complex, and cytK genes using PCR and sequencing. A total of 170 PCR amplifications targeting the hblA, nheA, nheB, nheC, and cytK genes were performed on 34 randomly selected strains. Of these, 69% (116/170) of the genes were successfully amplified, while 31% (54/170) were not detected. In-silico analysis of the wild-type hblA, nheA, nheB, nheC, and cytK genes confirmed their relation to B. cereus. Seven mutations were detected in the NheA_60-220region, including Q62N, Y64S, L82K, W96E, Y122D, D135N, and I213H. Four mutations were found in the NheA_270-380 peptide sequence: Q280N, I316V, D317E, and W330Y. In NheB, truncated tripeptides NheB_∆VKQ at position 34 and NheB_∆SQD at position 211 were identified. Additional NheB mutations included A213S, D154E, Y231L, G273V, and K283Y. No mutations were detected in the NheC or HblA proteins. Some key mutations significantly altered the predicted 3D structure of the NheA and NheB components. These conformational changes may explain the non-pathogenicity of B. cereus in traditional fermented foods and beverages, which are often consumed without sterilization treatment.

Probiotic Combination Effect on the Modulation of Lipid Metabolism in Triton X-100 Induced Hyperlipidemic Rats

Chinwendu N. Ozoh — 2025-12-02

Aim: This study evaluated the effect of a probiotic consortium (70% yeast, 30% bacteria) on lipid metabolism in Triton X-100/high cholesterol-induced hyperlipidemic rats.

Study Design: Male Wistar rats (50-110 g) were obtained from Onyewuchi Farm, a certified animal farm located at Ifite Awka, Anambra State. Rats were randomized into different groups.

Place and Duration of Study: The study was carried out in the laboratories of the Microbiology and Biochemistry Department of Nnamdi Azikiwe University, Awka, Nigeria. This study was conducted over duration of 2 months at intervals.

Methodology: Twenty-four Wistar rats were divided into four groups (n = 6): normal control, hyperlipidemic control (HCD), low-dose probiotic (30 mg/kg), and high-dose probiotic (40 mg/kg). The animals were acclimatized for seven days in the animal house and fed with normal animal feed. Hyperlipidemia was induced by administering a single injection of Triton X-100 intraperitoneally at a dose dependent on the weight (100 mg/kg body weight) of the rats. A normal control group of rats received an equivalent volume of saline. The rats were slaughtered after 14 days of probiotics bacteria and yeast combination treatment. The stomach content, blood, liver were harvested and used for further analysis. After 14 days of probiotic administration, biochemical and microbial analyses were performed.

Results: Rat fed with HCD fasting blood glucoses significantly increased to (90.33 mg/dL) when compared to the Normal Diet group which had 68.67 mg/dL. Treatment with Probiotic significantly reduced glucose levels to 53.33 mg/dL (low dose) and 76 mg/dL (high dose). The rats fed with HCD had the body weight gain of 22 g which was significantly higher than that of the Normal Diet group (17.67 g), while probiotic supplementation reduced weight gain to 18.33 g (low dose) and 17 g (high dose), Total cholesterol significantly increased (p < 0.05) in HCD rats (231.08 mg/dL) compared to the Normal group (135.99 mg/dL), but decreased markedly following probiotic treatment to 146.0 mg/dL (low dose) and 143.96 mg/dL (high dose). Similarly, triacyl glyceride levels rose significantly in HCD rats (342.92 mg/dL) but decreased to 238.75 mg/dL (low dose) and 249.58 mg/dL (high dose) after probiotic administration. LDL-C levels increased significantly in the HCD group (108.49 mg/dL) but were reduced to 99.92 mg/dL (low dose) and 60.78 mg/dL (high dose), while HDL-C dropped in the HCD group (52.89 mg/dL) and improved significantly with probiotic treatment to 50.44 mg/dL (low dose) and 76.22 mg/dL (high dose). Gut microbiota analysis showed that HCD reduced beneficial lactic acid bacteria (LAB) and increased coliform counts. Gastric analysis revealed that probiotics significantly increased gastric pH (p < 0.05) from 1.42 ± 0.10 (HCD) to 1.93 ± 0.08 (low dose) and 2.00 ± 0.12 (high dose), suggesting a buffering and gastroprotective effect, while total acidity and gastric volume were not significantly affected (p > 0.05).

Conclusion: The probiotic combination effectively ameliorated high-fat diet–induced hyperlipidemia, reduced LDL-C, elevated HDL-C, improved glycemic control, restored gut microbial balance, and protected gastric function. These findings support the potential of yeast–bacterial probiotic formulations as a functional dietary supplement for the management of hyperlipidemia and metabolic disorders.

Identification and Characterization of Xanthomonas axonopodis pv. dieffenbachiae: The Causal Agent of Bacterial Blight in Taro

Star Luikham — 2025-12-02

Taro, a versatile crop grown under diverse and adverse climatic conditions, is susceptible to several fungal, bacterial, and viral pathogens. Among these, bacterial leaf blight caused by Xanthomonas axonopodis pv. dieffenbachiae (Xad) is a major disease, leading to severe damage and significant losses to crop growth and yield. The disease primarily affects the foliage, resulting in reduced productivity. Initial disease symptoms appear as small, star-shaped, water-soaked spots that later expand into V-shaped, irregular brown necrotic patches surrounded by a yellow margin, especially in dry weather. The bacterial isolates were Gram-negative, small rod-shaped cells and exhibited close similarity to Florida strains of Xad, as confirmed through morphological characterization, biochemical tests, pathogenicity assays and molecular analysis, and field emission scanning electron microscopy (FESEM). FESEM imaging revealed the isolates as short rod-shaped cells measuring 572.26–614.21 nm in width and 1071.05–1275.23 nm in length. Timely and accurate identification of the pathogen is critical for implementing effective management strategies and enabling prompt application of control measures for sustainable and profitable cultivation of Taro.

Seasonal Dynamics of Multidrug-Resistant Escherichia coli and Potential for Bacteriophage Based Biocontrol from Wastewater in Mumbai, India

Niyoti Jayakar — 2025-12-02

Aims: The global emergence of multidrug-resistant (MDR) pathogens poses a severe threat to public health, with wastewater treatment plants (WWTPs) emerging as critical reservoirs for the dissemination of antibiotic resistance. This study investigated the seasonal prevalence of MDR Escherichia coli strains in six different WWTPs across Mumbai and isolated bacteriophages against them, exploring the potential of bacteriophages as a sustainable biocontrol strategy.

Study Design: A cross-sectional study was conducted over 12 months to analyze seasonal trends of MDR E. coli and isolate corresponding bacteriophages from wastewater.

Place and Duration of Study: Samples were collected from six WWTPs across Mumbai, India, over a 12-month period.

Methodology: A total of 106 E. coli strains were isolated from wastewater samples. Among them, 86 (81.1%) were identified as multidrug-resistant based on resistance to more than three antibiotics. Seasonal distribution and resistance profiles were analyzed statistically. Bacteriophages were isolated and characterized for plaque morphology and host range using the enrichment and double-layer agar methods.

Results: The occurrence of MDR E. coli showed a distinct seasonal trend, peaking during winter (48%), followed by summer (28%) and monsoon (24%), indicating the influence of climatic and environmental factors. Statistical analysis confirmed that the variation in seasonal prevalence was significant (χ²= 8.11, df = 2, p < 0.05). Resistance profiles varied across seasons and antibiotic classes, with β-lactam resistance notably reduced during the monsoon, possibly due to environmental dilution or degradation. Penicillin G and erythromycin maintained high resistance across all seasons. Bacteriophages were successfully isolated against 55 of the 86 MDR E. coli strains. Characterization of the phage isolates revealed varied but often multi-strain host ranges, and lytic activity was confirmed through clear plaque formation.

Conclusion: This study provides critical insights into the seasonal dynamics of MDR E. coli in urban wastewater and establishes the potential of bacteriophages as effective tools for controlling antibiotic-resistant bacteria. Integrating environmental surveillance with phage-based interventions may contribute significantly to mitigating the global antibiotic resistance crisis.

Sensory Analysis of Greek Style Yoghurt Sauce with Blends of Whey Protein Concentrate and Virgin Olive Oil

Vaishnavi D — 2025-12-03

Aims: To evaluate the influence of whey protein concentrate (WPC-80) and virgin olive oil fortification on the sensory profile of a Greek style yoghurt sauce and to optimize their inclusion levels for achieving the highest consumer sensory acceptance

Study Design: A laboratory-based product optimization study was conducted using a completely randomized design (CRD), evaluating the sensory response of Greek style yoghurt sauce fortified with varying concentrations of WPC-80 and virgin olive oil.

Place and Duration of Study: This research work was carried out in the Department of Dairy Technology, Dairy Science College, Hebbal, Bengaluru, Karnataka, India, over the duration spanning from December 2024 to October 2025.

Methodology: Cow milk standardized to 3.5% fat and 8.5% SNF was cultured with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus for Greek style yoghurt preparation. The product was fortified with whey protein concentrate (WPC-80) at inclusion levels of 1%, 2%, and 3% to improve protein content and textural attributes, while virgin olive oil was incorporated at 8%, 10%, and 12% to enhance flavour and mouthfeel characteristics. Sensory quality was assessed by a trained panel of 20 judges using a 9-point hedonic scale for flavour, colour and appearance, body and texture, and overall acceptance. Data obtained from sensory trials were statistically evaluated through ANOVA, and treatment differences were compared using the Critical Difference (CD) test at a 5% probability level (P ≤ 0.05).

Results: Incorporation of 3% WPC-80 improved the flavour, body, and texture of the sauce by strengthening the protein structure, giving the best overall acceptance. For olive oil, 10% addition provided the right level of creaminess, appearance, and taste, while 12% made the sauce too oily and reduced liking. The combination of 3% WPC-80 and 10% virgin olive oil resulted in a stable sauce with the most favourable sensory scores.

Conclusion: The optimized formulation with 3% WPC-80 and 10% virgin olive oil was found to be the most acceptable, indicating strong potential for developing a protein-enriched, health-oriented Greek style yoghurt sauce with desirable sensory attributes.

An Ongoing Diphtheria Epidemic in Guinea: Epidemiological and Microbiological Study from 2023 to 2025

Mamadou Bobo Diallo — 2025-12-04

Objectives: This study describes the epidemiological and microbiological characteristics of Corynebacterium species cases between 2023 and 2025, to guide surveillance, prevention, and management.

Study type: A descriptive cross-sectional study was conducted in six affected health regions.

Study location and duration: All oropharyngeal or nasopharyngeal swabs meeting WHO definitions of suspected cases were centralized at the bacteriology laboratory of the National Institute of Public Health between 2023 and 2025

Methods: Bacterial identification was performed by culture on selective media (potassium tellurite agar 3.5% and Colombian agar with 5% sheep blood) and using the Corne API, and antibiotic susceptibility testing (using disk diffusion method on Mueller-Hinton agar enriched with horse blood) was interpreted according to CA-SFM/EUCAST 2023 standards.

Results: Of 997 samples received, 914 were included. The median age of the patients was 7 years (IQR: 3–15 years), with a predominance of children aged 0–4 years (33.9%). The Kankan region accounted for 68.4% of reported cases. Culture was positive in 17.9% of cases (n = 164). Corynebacterium diphtheriae biovar mitis was the predominant strain (80.5%), followed by C. pseudodiphtheriticum (12.8%) and C. diphtheriae biovar gravis (6.1%). The C. diphtheriae strains showed complete susceptibility to erythromycin but high resistance to β-lactams and tetracyclines. Only one death was reported (case fatality rate of 0.1%).

Conclusion: The diphtheria epidemic in Guinea is characterized by persistent transmission, primarily affecting young children, with a high geographic concentration. The results support the use of macrolides as first-line therapy, the restriction of tetracyclines and cotrimoxazole, and highlight the need to strengthen childhood vaccination and microbiological surveillance.

Screening of Lactic Acid Bacteria from Poultry Droppings for Probiotic Potential

S.H. Etumabo — 2025-12-08

Background: Globally, with the advent of industrial-scale intensification of poultry rearing, improved health and performance of chicken due to inclusion of sub-therapeutic levels of antibiotics in feeds have gained acceptance. The poultry industry has responded with development of probiotic, direct-fed microbials/prebiotic products. The probiotic bacteria supplemented in prevention dose had been reported to produce performance in poultry similar to antibiotics. Research has shown that among the probiotics, Lactobacillus species appears to be particularly stable and numerically significant in animal studies.

Aim: The present study assesses screening of Lactic Acid Bacteria from Poultry Droppings for Probiotic Potential.

Materials Methods: The study was conducted at the Microbiology Laboratory of Abubakar Tafawa Balewa University Bauchi, Bauchi state, Nigeria, between April to July, 2025. Faecal samples were collected from local chicken and enriched in buffered peptone water (Oxoid, UK) in a 1:10 sample to broth ratio at 37°C for 18 hours. 10g of freshly collected faeces were suspended separately in 90 ml of 1% peptone water (pH 3.5) for 2h at 37^oC. Tenfold dilution was then carried out in sterile peptone water and appropriate dilutions of each sample pour plated in de Man Rogosa Sharpe (MRS) media (Oxoid, CM0359). The inoculated plates were then incubated at 37°C for 72 h. From each sample, 15–30 colonies were randomly selected and purified by streaking on MRS agar plates. Morphologically distinct colonies were purified by sub-culturing each 3 times in MRS Agar media (Oxoid, CM0359) plates until pure culture was obtained. Distinctive pure isolates obtained were sub-cultured in MRS agar slant and maintained at 4°C every 4 weeks. The isolates were further identified using the following biochemical test. Pure cultures of bacterial isolates were grown on MRS agar for 18hours. The rapid identification of different strains using the API 50 CH kit (Biomerieux. France) a standardized system was used to differentiate Lactic acid bacteria (LAB) isolates at strains level. The potential probiotic bacteria strain was subjected to Bile salt resistance test, Tolerance to acidic pH, and Antibiotics sensitivity tests.

Results: Lactobacillus brevis (10.00%), Lactobacillus fermentum (15.6%), Lactobacillus acidophilus (37.80%) and Lactobacillus plantarum (36.60%) were isolated and identified. Results after determining the probiotic properties of the isolates revealed that all isolates showed acceptable survival at acidic pH and tolerant to high concentration (1.0%) of bile salt hence they can survive the gastrointestinal tract. All of the isolated Lactobacillus species were also found to be resistant to streptomycin and kanamycin but sensitive towards tetracycline, ampicillin, and erythromycin. Probiotic properties of the isolates revealed that all isolates showed acceptable survival at acidic pH and tolerant to high concentration (1.0%) of bile salt hence they can survive the gastrointestinal tract. All of the isolated Lactobacillus species were also found to be resistant to streptomycin and kanamycin but sensitive towards tetracycline, ampicillin, and erythromycin.

Conclusion: In this study, four Lactobacillus isolates from chicken droppings were found to have potential probiotic characteristics. These LAB strains are ideal probiotic candidates which can be used in vivo to increase poultry performance and for biocontrol of intestinal pathogens.