Microbiological Methods Research Articles

Bioinformatic challenges in metagenomic next generation sequencing data analysis while unravelling a case of uncommon campylobacteriosis.

Bioinformatic challenges in metagenomic next generation sequencing data analysis while unravelling a case of uncommon campylobacteriosis.

Feeding preferences and digestion of talitrids in a Bay of Fundy, Canada salt marsh

The function of detritivores in salt marsh ecology still presents many unknowns. We experimentally investigate the food preferences of two talitrids found in Bay of Fundy salt marshes: Orchestia grillus (Bosc, 1802) (= Speziorchestia grillus Bosc, 1802) and Platorchestia exter Myers & Lowry, 2023. Food preferences were found to depend on: 1.The availability of marsh plant litter at the supralittoral level where the talitrids live.2.The degree of physical/microbiological decay of the plants present in marsh litter.3.The talitrid ecotype that is doing the consuming. Our food preference experiments with different plant foods in culture conditions confirm that O. grillus is a palustral specialist limited to a single plant food class which contains structural lignocelluloses. P. exter is a wrack generalist able to acclimate in experimental cultures to a range of decaying plant foods including those containing structural celluloses (Phaeophyta) and lignocelluloses (Angiosperms). These results confirm the applicability of the generalist/specialist continuum within the Talitridae. Cellulolytic microbiological culture methods applied to dissected gut parts of O. grillus are consistent with the hypothesis that the midgut is where endosymbiotic enzyme activity occurs. The digestive enzymes originate from both resident hepatopancreatic and ingested microbes.

Utilizing Microbiological Techniques: The Residual Microorganisms in Poultry Flesh Raised at Random Between 2024 and 2025

Veterinary biomass is an effective resource used throughout the rural areas of the study region. However, animal use is unclear and can lead to unhealthy debt management, thus contributing to animal consumption, and even to the environment. This study aimed to evaluate the presence of biomass in poultry meat using microbiological methods based on traditional methods recommended and approved by the French Food Safety Authority. For this purpose, 150 poultry meat samples were taken from different farms and directly examined using a standardized agar diffusion technique, cultured with two strains: Bacillus licheniformis and Staphylococcus aureus. After 110 original analytical results were generated from 150 poultry meat samples, the diagnostic result was 73% for antibiotic residues. However, most of them contained 36.36% oxytetracycline, 22.72% penicillin, and 9% sulfadimidine. In contrast, gentamicin yielded a positive rate of 31.8%. This suggests to physicians that these medications are being used indiscriminately and without specific treatment, without a prescription, or following the protocol and health requirements for the use of vital types of insurance, and adhering to the drug withdrawal period. This leads to the permanent presence of these meats, and farmers are also failing to adhere to the 45-day marketing period, all of which will harm consumers.

Clinical value of metagenomic next-generation sequencing in screening oropharyngeal colonization in patients undergoing allogeneic hematopoietic stem cell transplantation: a prospective observational study.

Screening for colonization is essential for predicting infection risk in allo-HSCT patients. Traditional microbiological testing methods, however, are time-consuming and have low sensitivity. In this paper, we examine the impact of oropharyngeal colonization on outcomes following allo-HSCT while also evaluating the utility of mNGS for detecting colonization. Our investigation reveals that screening for oropharyngeal colonization using mNGS provides critical clinical value in predicting transplant outcomes and prognosis. Additionally, not all colonization has clinical relevance, but oropharyngeal Enterobacteriaceae colonization has negative impacts on transplant prognosis. Colonization by CRE had particularly severe consequences, which warrants serious attention. This study is registered as a single-center clinical trial (Registration No. ChiCTR2300069450).

Molecular Characterization of Antibiotic Resistance Genes in Hospital-Acquired Urinary Tract Infections

Introduction: Hospital-acquired urinary tract infections (HAUTIs) represent a major challenge in healthcare due to increasing multidrug resistance (MDR) among causative pathogens. Objective: This study aimed to molecularly characterize antibiotic resistance genes in bacterial isolates from HAUTI patients and assess their antimicrobial susceptibility profiles. Methodology: A total of 150 urine samples were collected from hospitalized patients diagnosed with HAUTIs. Bacterial isolates were identified using standard microbiological methods, and antibiotic susceptibility testing was performed following Clinical and Laboratory Standards Institute (CLSI) guidelines. Phenotypic screening for extended-spectrum beta-lactamase (ESBL) and carbapenemase production was conducted, followed by polymerase chain reaction (PCR) assays targeting key resistance genes including bla_CTX-M, bla_TEM, bla_SHV, bla_NDM, bla_OXA-48, and bla_KPC. Results: Out of 114 isolates recovered, Escherichia coli (40.4%) and Klebsiella pneumoniae (24.6%) were predominant. High resistance rates were observed against third-generation cephalosporins, fluoroquinolones, and carbapenems, with 68.4% of isolates classified as MDR. ESBL production was confirmed phenotypically in 57.0% of isolates, predominantly in E. coli and K. pneumoniae. Carbapenemase activity was detected in 25.4% of isolates, especially in K. pneumoniae and Acinetobacter baumannii. PCR analysis revealed bla_CTX-M as the most prevalent gene (66.7%), followed by bla_TEM (48.7%) and bla_NDM (26.9%). Conclusion: Co-occurrence of multiple resistance genes was common, highlighting the complexity of resistance mechanisms. The study underscores the critical need for continuous molecular surveillance and stringent antimicrobial stewardship to effectively manage HAUTIs and prevent the spread of resistant pathogens in healthcare settings.

Prevalence and Antimicrobial Resistance of Listeria monocytogenes Isolated from Dairy Products in Romania.

Background/Objectives:Listeria monocytogenes is a significant foodborne pathogen associated with dairy products, which can pose serious public health risks, particularly for vulnerable populations. This study aimed to assess the prevalence, serotype distribution, and antimicrobial resistance profiles of Listeria monocytogenes isolated from dairy products collected in Romania over a three-year period (2021-2023). To the best of our knowledge, this is the first comprehensive study addressing these issues within the country. Methods: A total of 10,306 dairy samples, including milk, cheeses, ice cream, yogurt, and other dairy-based products, were collected and analyzed using standard microbiological methods. Molecular serotyping was performed to identify the most common serogroups. The antimicrobial susceptibility of the isolates was also conducted. Results: The overall prevalence of Listeria monocytogenes was 0.41% (43/10,306). The most frequently detected serogroup was IVb (74.41%), followed by IIa (23.25%) and IIb (2.32%). Ice cream was the most affected product, followed by fresh telemea made from cow milk. Antimicrobial susceptibility testing revealed higher resistance rates for oxacillin and trimethoprim-sulfamethoxazole (13.95% each), while all isolates were susceptible to ciprofloxacin, levofloxacin, and moxifloxacin. Conclusions: The findings emphasize the need for continuous monitoring of Listeria monocytogenes in dairy products, particularly ice cream and fresh cheeses, due to their high contamination rates. The study's results are valuable for comparative analysis with findings from other countries, helping to establish a broader understanding of Listeria monocytogenes contamination trends and resistance profiles.

Recent Trends in Food Quality and Authentication: The Role of Omics Technologies in Dairy and Meat Production.

The global demand for animal protein presents significant challenges in the production of nutritionally rich foods, such as milk and meat. Traditionally, the quality of these products is assessed using physicochemical, microbiological, and sensory methods. Although effective, these techniques are constrained by time limiting their widespread application. Furthermore, growing concerns regarding sustainability, animal welfare, and transparency have driven the development of technologies to enhance the rapid and precise assessment of food quality. In this context, omics technologies have transformed the characterization of animal-origin food by providing in-depth molecular understanding of their composition and quality. These tools enable the identification of biomarkers, adulteration detection, optimization of nutritional profiles, and enhancement of authentication and traceability, facilitating the development of functional foods. Despite their potential, several barriers persist, including high implementation cost, the need for specialized infrastructure, and the complexity of integrating multi-omics data. The main aim of this review was to provide information on advances in the application of omics technologies in dairy and meat production systems and studies that use them in food quality, authentication, and sustainability. It also outlines opportunities in areas such as fraud prevention and functional product development to support the transition to safer, healthier, and more transparent food systems.

Fabrication of a plasmonic-nose sensor for rapid identification of plant pathogenic bacteria based on optoelectronic analysis

Plant pathogenic bacteria are one of the most important threats to agriculture production, diminishing the growth and development of host crops. Bacterial diagnostic is based on traditional microbiological methods, including isolation, purification, and a further confirmatory immunological or molecular test for accurate identification. In this work, we present the design and fabrication of a plasmonic optoelectronic sensor based on seven “olfactory receptors” formed by seven gold nanoparticle (AuNP) morphologies, including nano bones, nanospheres, nanorods, and nano shuttles with two sizes and nanostars. The AuNPs work as a central part of the sensor for color change analysis, the principle of which is based on the reduction of Tollens’ reagent with aldehydes produced by the tested phytopathogenic bacteria during their growth. Depending on the concentration and redox potential of the produced aldehydes, the reduction of Tollens’ reagent will be a critical step in differentiating between bacteria species. A photograph captures the colorimetric response, and then the RGB values are extracted with an image analysis algorithm designed and presented here. Our results show clear chemical discrimination between five plant pathogenic bacteria after 3 h of incubation in the sensor; no misclassification was observed after this incubation time using hierarchical cluster analysis and linear discrimination analysis. In an experimental model, the sensor correctly classified Pseudomonas savastanoi pv. phaseolicola isolated from halo blight symptomatic leaves and distinguished between other fluorescent bacteria isolated from bean leaves. In addition, the image analysis algorithm presented here can improve RGB extraction due to removing interferences in the sensor substrate compared with the already reported RGB color extraction methods.

Diagnostic value of metagenomic next-generation sequencing in patients with osteoarticular infections: a prospective study.

Due to the limits of traditional microbiological methods and the complexity of osteoarthritis pathogens, only a few pathogens can be detected. We evaluated metagenomic next-generation sequencing (mNGS) for detecting pathogens in osteoarthritis infection samples. We prospectively included 150 patients with osteoarthritis infection who visited the Orthopedics Department of Shandong Provincial Public Health Center from 2023 to 2024, including 124 cases of primary osteoarthritis (POI) and 26 cases of invasive osteoarthritis (IOI). The most common pathogenic bacteria were Mycobacterium tuberculosis complex, Staphylococcus aureus, and Brucella melitensis. mNGS (75.33%) significantly improved the detection of pathogens in osteoarticular infections compared to conventional tests (CT) methods (36.67%). mNGS could detect a wider spectrum of pathogens compared to CT methods, especially for mixed and rare pathogens. The treatment strategies for patients with osteoarthritis infection could be adjusted based on the results obtained from mNGS testing. Furthermore, the abundance of M. tuberculosis complex, B. melitensis, and Staphylococcus epidermidis was significantly correlated with clinical indicators.IMPORTANCEIdentifying the microorganisms responsible for osteoarthritis infection could help with early diagnosis and treatment. In this study, we compared the pathogen detection rate of metagenomic next-generation sequencing (mNGS) and CT methods in patients with osteoarthritis infection and found that mNGS had a higher microbial detection rate and a broader spectrum of pathogens (especially for mixed pathogens). This study demonstrates that mNGS is an ideal tool for detecting pathogens in patients with osteoarticular infections.

Optimizing MALDI-TOF Mass Spectrometry for the Identification of Bacillus cereus: The Impact of Sporulation and Cultivation Time.

Bacillus cereus is a significant foodborne pathogen that presents a critical challenge in food safety due to its ability to form resistant spores and produce various toxins. The potential for severe food poisoning makes rapid and accurate identification of this pathogen essential. Conventional microbiological methods for B. cereus identification rely on morphological characteristics and biochemical tests, requiring extensive time and labor. However, even automated biochemical systems like VITEK2, while providing reliable results, still require up to 16 h for analysis and complex sample preparation procedures. MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry utilizes laser-induced ionization of bacterial proteins and subsequent time-of-flight analysis to generate unique mass spectral patterns. This established analytical technique for bacterial identification offers exceptional speed and simplicity through direct protein profiling. In this study, we optimized MALDI-TOF analysis conditions for B. cereus identification by examining various cultivation times. Our results demonstrated complete species-level identification accuracy with MALDI-TOF scores ≥ 2.0 with 12-h cultures, matching the reliability of VITEK2 while significantly reducing processing time. The identification rates decreased significantly from 100% at 12 h to 73.3% at 24 h and 50% at 48 h of incubation, correlating directly with increased spore formation. Detailed analysis at 4-h intervals revealed that high identification rates (93.3%) were maintained during 16 h of cultivation before declining significantly. This study establishes MALDI-TOF as a reliable and efficient tool for rapid B. cereus identification, representing a significant advancement in food safety diagnostics with potential time savings of more than 50% compared to conventional methods.

Tools and strategies for monitoring hospital environmental hygiene services.

Tools and strategies for monitoring hospital environmental hygiene services.

Invited review: Combined mitigation of methane and ammonia emissions from dairy barns through barn design, ventilation and air treatment systems.

Invited review: Combined mitigation of methane and ammonia emissions from dairy barns through barn design, ventilation and air treatment systems.

Evolving Resistance Patterns: A Retrospective Five-year Study of Urinary Pathogens and Antibiotic Efficacy

Introduction: The rising incidence of antimicrobial resistance is a major source of concern, particularly in the absence of new antimicrobial agents. This infection arises when microorganisms (predominantly bacteria) infiltrate and multiply within the urinary tract. Aim: To we present the changing antibiotic sensitivity patterns of urinary pathogens over the past five years (2019-2023) in a hospital located on the northeast coast of Tamil Nadu, India. Materials and Methods: This retrospective study was performed at the Department of Microbiology, Chettinad Hospital and Research Institute, Tamil Nadu, India, from January 2019 to October 2023. Out of 39,592 urine samples, 9,940 samples with bacterial growth were included in the study, considering only those with positive bacterial growth. Exclusion criteria included samples with no bacterial growth, samples from patients who had received antibiotics before sample collection, and duplicate samples. The demographic parameters considered were age, gender and co-morbidities. Bacterial identification was performed using conventional microbiological methods, including Gram staining, catalase testing, oxidase testing and biochemical tests. Antibiotic resistance testing was conducted using the Kirby-Bauer disk diffusion technique, following the protocols established by the Clinical and Laboratory Standards Institute (CLSI). Statistical analysis was performed using the Chi-square test, with a p-value under <0.05 regarded as statistically significant. Results: The study processed 39,592 urine samples, from which 9,940 (25.1%) pathogens were isolated. Escherichia coli (4,406; 44%) and Klebsiella pneumoniae (1,730; 17%) were the most common Gram-Negative Bacteria (GNB), while Enterococcus spp. (1,305; 13%) dominated among Gram-Positive Cocci (GPC). Notably, the efficacy of Amikacin (AK) against E. coli, Citrobacter koseri and Pseudomonas aeruginosa has declined over the last five years, as has the penicillin class of antibiotics, such as penicillin against Staphylococcus aureus. However, certain antibiotic classes like cephalosporins, aminoglycosides, Cotrimoxazole (COT), and Ciprofloxacin (CIP) exhibited improved efficacy against GNB. COT and Clindamycin (CD) also demonstrated notable effectiveness against Staphylococcus aureus, highlighting evolving antibiotic susceptibility patterns. Conclusion: From 2019 to 2023, there was a noticeable decrease in the efficacy of amikacin against E. coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, as well as a decrease in penicillin effectiveness against S. aureus. However, Imipenem (IMP), Meropenem (MRP), and Gentamicin (GEN) remained effective against GNB. Oxazolidinones, glycopeptides and sulfonamide antibiotics showed positive efficacy against GPC, highlig

Use of MALDI-TOF to identify cryopreserved mastitis pathogens collected from 2003 to 2011 that were originally identified using conventional microbiological methods

Use of MALDI-TOF to identify cryopreserved mastitis pathogens collected from 2003 to 2011 that were originally identified using conventional microbiological methods

Biomedical parameters assessed in pregnant mice receiving oral commercial nanosilver preparations

The aim of the work was to determine the safety of oral commercial colloidal nanosilver preparations during mouse pregnancy by assessing microbiota and local colonic nonspecific resistance; pregnancy course and outcome; morphology of vital organs — kidneys, liver, brain in pregnant mice and paired offspring. Microbiological, biochemical, and histological research methods were used in the work. Empirically selected commercial colloidal nanosilver preparations (“Ajenta”, “Vitargol”) recommended for internal use in humans at a therapeutic dose were used in an in vivo experiment by 30-day watering of pregnant mice. As a result, the large intestine microbiome balance was restored due to decreased in number of pathogens: enterobacteria, Staphylococcus and Candida. In the coprofiltrates of both groups of mice receiving both “Adjenta” and “Vitargol”, the state of local nonspecific resistance showed impaired local antiradical protection. If after “Adjenta” therapy there was an imbalance in antioxidant enzyme system, when the activity of superoxide dismutase was 1.5 times higher than control level, and catalase activity was 2 times lower contributing to higher level of peroxidation product — malondialdehyde by 2.6 times, then after “Vitargol” therapy activity of superoxide dismutase and catalase was only 43% and 25%, and the amount of malondialdehyde peaked reaching 431%. Microscopic examination of all organ biopsies from mice receiving commercial colloidal nanosilver preparations “Ajenta” and “Vitargol” revealed no fundamental differences. At the same time, morphological changes in tissues were found in all animals: granular dystrophy of hepatocytes, nephrocytes of the proximal and distal tubules, perinuclearly in liver preparations there is a cytoplasm enlightenment in some liver cell types. In all brain samples, there is moderate perivascular-pericellular edema, vascular fullness, neuron dystrophy. However, breast-fed mouse pup liver histological examination from paired female mice after oral Vitargol intake revealed no negative changes. Despite the fact that the processes of gestation and childbirth in mice proceeded normally, the results of the study indicate insufficient safety of the selected drugs for oral use during pregnancy.

Antimicrobial susceptibilities of Aeromonas species isolated from medical leeches

The aim of this study was to determine the antibiotic susceptibility of Aeromonas species isolated from their environment and leeches are grown for use in medical treatment. The water samples and two leeches which 2-10 g weight from a leech hatchery were brought to XXXXX. The samples were cultured on blood agar base added 7% defibrined sheep blood and MacConkey agar at 18-20 hours and 37C. Besides the samples were incubated on two Sabourrauds’ Dextrose agar supplemented chloramphenicol at 20 C and 37C for 10 -14 days. Two different colonies was detected to be Aeromonas spp. by conventional microbiological methods such as Gram staining, haemolysis, catalase, oxidase, triple tube methods. These colonies were identified to be Aeromonas hydrophila and Aeromonas veronii on species level by Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry, too. According to antimicrobial susceptibiliy tests, while Aeromonas hydrophila and Aeromonas veronii isolates were found resistant to amoxycillin, ampicilin, gentamicin, erytromycin, oxacillin and penicillin, these isolates were susceptible to ceftriaxone, enrofloxacin, florfenicol and trimethoprim-sulphamethaxazole. Because of isolation and identification of Aeromonas hydrophila and Aeromonas veronii from medical leeches and its environmental, and antimicrobial resistances to several antibiotics, leech therapy may be a potential public health problem for humans.

Antibiotic resistance and prevalence of bacterial contaminants in street-vended suya meat in Benin City, Nigeria

This study investigates the antibiotic resistance and prevalence of bacterial contaminants in street-vended suya meat in Benin City, Nigeria. Suya meat, a popular street food, is vulnerable to bacterial contamination due to improper handling, storage, and environmental exposure. A total of fifty (50) suya meat samples were collected from various vendors across the city for microbiological analysis. Standard microbiological methods were employed to isolate and identify bacterial pathogens, including Bacillus spp., Citrobacter spp., Klebsiella spp., Escherichia coli, Pseudomonas spp., Salmonella spp., and Staphylococcus aureus. The prevalence of bacterial contamination showed that 46% of samples were positive for Escherichia coli, 38% for Staphylococcus aureus, and 30% for Pseudomonas spp. Antibiotic susceptibility testing was performed using the disc diffusion method, revealing a high resistance rate, particularly among E. coli (70%), Klebsiella spp. (60%), and Pseudomonas spp. (55%) against ampicillin and tetracycline. Salmonella spp. displayed resistance to ampicillin (50%) and ciprofloxacin (40%). The analysis showed that Staphylococcus aureus was resistant to penicillin (50%) and clindamycin (45%). Statistical analysis conducted with SPSS version 23 revealed significant differences in antibiotic resistance patterns across bacterial species (p < 0.05). The results showed high resistance to Pefloxacin, Gentamycin, and Cotrimoxazole across most bacterial species, with Pseudomonas and Klebsiella exhibiting the highest resistance rates. Statistical analysis revealed significant correlations in antibiotic resistance between certain bacterial species, notably between Citrobacter and Klebsiella (r = 0.939, p = 0.0001) and between Pseudomonas and Salmonella (r = 0.773, p = 0.015). The results showed that E. coli emerged as the predominant pathogen, followed by Pseudomonas species and Staphylococcus aureus as major contributors to contamination. This study underscores the public health risk posed by bacterial contamination in street-vended suya meat, emphasizing the need for improved food safety measures and regulatory oversight to mitigate foodborne infections in Nigeria.

Nutritional value of ensiled Guizotia abyssinica (L. f.) Cass. (Noug: Niger) treated with salt, molasses, urea or barley.

The research aimed to assess the nutritional value of ensiled Guizotia abyssinica (L. f.) Cass. (GA), also known as Noug or Niger, when treated with various additives, including urea, salt, molasses, and barley. The eight treatment groups were as follows: (I) GA forage without any supplementation (control), GA with supplement (II) 1% salt, (III) 2.5% molasses, (IV) 2.5% urea, (V) 5% barley, (VI) 2.5% molasses + 1% salt, (VII) 2.5% urea + 1% salt, (VIII) 5% barley + 1% salt supplement with GA. Silage samples were analyzed using physical, chemical, and microbiological methods to determine their nutritional composition, sensory characteristics, and microbial content. The objective of this analysis was to provide a comprehensive and objective evaluation of the silage samples. Based on the assessment of relative feed value (RFV) and relative forage quality (RFQ), it was determined that GA forage supplemented with 2.5% urea produced the highest-quality silage. The findings suggest that GA forage has the potential to serve as a high-quality silage. It is recommended that GA forage be ensiled with various additives at different inclusion rates. Further research is required to establish its in vitro digestibility and assess animal preference in vivo.

Management and microbial monitoring of final rinse water for flexible endoscopes in 290 hospitals in Jiangsu Province, China: a multicenter cross-sectional study

BackgroundThere is a lack of a universally accepted standard or guideline for the frequency of disinfection in purified water pipelines. Furthermore, there is no standardized method for detecting microorganisms in the final rinse water utilized for endoscope cleaning.This study aims to examine the current management and microbial monitoring practices concerning the final rinse water used for flexible endoscope cleaning in medical institutions.MethodsA questionnaire was designed using a convenience sampling method to gather data on the maintenance and microbial monitoring of final rinse water for flexible endoscopes in 290 medical institutions across Jiangsu Province, China.ResultsPurified water is used for endoscope rinsing by 93.45% of institutions, with 78.62% employing centralized water supply. Membrane filtration devices at the terminal are installed by 82.07%, mainly with a 0.2μm pore size (76.47%), and are replaced quarterly (32.77%). Disinfection devices are present at 52.76% of terminals, with varied disinfection frequencies; chlorine-containing disinfectants (48.15%) and peracetic acid (34.92%) are predominant. Inadequate disinfection, filter membrane neglect, sampling contamination, and biofilm formation are identified as reasons for non-compliant final rinse water. Actions include filter replacement, pipeline disinfection, and flushing. Microbial mornitoring occurs quarterly (70.96%), with faucet outlets as primary sampling sites. Standards are based on 10cfu/100ml (87.58%), using membrane filtration (40.81%) and nutrient agar plates (82.72%). A cultivation period of 2 days predominated (72.43%), with a temperature range of 35-37°C (76.47%).ConclusionWhile purified water and terminal filters are common for final rinsing of endoscopes, there is variation in maintenance and supply line disinfection. Current microbiological methods’ reliability is considered low, necessitating further research to establish unified standards for effective endoscope final rinse water management and monitoring.

Antimicrobial Activities of Lactic Acid Bacteria Isolated from Fermented Food on Some Food Spoilage Organisms

Aims: To determine the antimicrobial potency of lactic acid bacteria isolated from fermented food products. Place and Duration of Study: Department of Microbiology, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria. Methodology: Lactic acid bacteria were isolated using De Mann, Rogosa and Sharpe agar and identified using cultural, morphological and molecular techniques. Spoilage bacteria were isolated from spoiled tomatoes using standard microbiological methods. Isolated lactic acid bacteria were screened for antimicrobial activity. Crude bacteriocin of isolates which exhibited significant inhibition against food spoilage organisms were extracted and used for antimicrobial assay. Results: Lactic acid bacteria which exhibited significant inhibitory activity against the test organisms were identified as Lactobacillus plantarum and Lactobacillus fermentum while spoilage bacteria isolated from spoiled tomatoes were Enterobacter aerogenes, Pseudomonas aureginosa and Bacillus cereus. Lactobacillus plantarum and Lactobacillus fermentum Crude Bacteriocin Extracts exhibited highest inhibition against Bacillus cereus. Both Crude Bacteriocin Extracts exhibited highest inhibitory activity against the spoilage organisms at 40oC with zones of inhibition of 16mm and 15mm respectively against Bacillus cereus. There was significant difference in the inhibition of the test organisms at different temperatures (P = 0.05). Both Crude Bacteriocin Extracts exhibited maximum inhibitory activity at pH 4. There was significant difference in the inhibition of the test organisms at different pH 4 (P = 0.05). The inhibitory activity of the Crude Bacteriocin Extracts decreased with increased storage time at a constant temperature of 37oC. Conclusion: Bacteriocins produced by Lactobacillus plantarum and Lactobacillus fermentum exhibited significant inhibitory activity against food spoilage bacteria.