Chand Ram

Bacillus licheniformis is an important spoilage-associated bacterium in the food and dairy industries owing to its ability to form persistent biofilms and withstand conventional sanitation treatments. Screening of 42 samples collected from dairy-associated and environmental sources resulted in the isolation of six lytic bacteriophages (SAR 01–SAR 06) infecting B. licheniformis. The phages were characterized for their morphology, host range, physicochemical stability, infection kinetics, and biocontrol potential. TEM analysis revealed that all phages belonged to the family Siphoviridae and possessed an icosahedral head of approximately 90–100 nm in diameter and a contractile tail of 120–140 nm in length. Host range analysis demonstrated that phage SAR 02 exhibited the broadest host spectrum, infecting strains belonging to nine Bacillus species, whereas SAR 04 displayed the narrowest host range. Most phages infected different strains of B. licheniformis as well as selected Geobacillus and other Bacillus species, while none infected Escherichia coli or Pseudomonas spp. The phages were highly sensitive to pH 2, alkaline conditions, exposure to 80°C, and nitric acid treatment. Additionally, phages SAR 01, SAR 02, and SAR 03 were inactivated by 0.9% sodium dodecyl sulphate (SDS) and 0.4% sodium hydroxide (NaOH). One-step growth curve analysis revealed latent periods ranging from 20 to 40 min and an average burst size of approximately 100 plaque-forming units per infected cell. The phages effectively inhibited the growth of B. licheniformis in vitro and prevented biofilm formation on food-contact surfaces. These findings highlight the potential of lytic bacteriophages as eco-friendly biocontrol agents for managing B. licheniformis contamination and biofilm-associated spoilage in dairy processing environments.

The safety assessment of probiotic bacterial strains has become increasingly essential due to potential health concerns linked to their use under various medical conditions. In this study, we applied in vitro methods, in accordance with FAO/WHO and ICMR/DBT guidelines, to assess the safety profile of two native probiotic strains, Lactiplantibacillus plantarum HD48 and HD51 in accordance with the guidelines set by FAO/WHO and ICMR/DBT. Different assays were conducted to evaluate mucin degradation and blood hemolysis activity, antimicrobial susceptibility, the presence of virulence factors and production of biogenic amines. Lactiplantibacillus plantarum HD48 and HD51 were found to be non-hemolytic and non-mucinolytic. High-performance liquid chromatography (HPLC) analysis revealed the strains did not produce biogenic amines, such as cadaverine, histamine, tyramine and putrescine. Lpb. plantarum HD48 and HD51 were found to be susceptible to most of the antibiotics tested, with the exception of resistance to vancomycin and nalidixic acid; HD48 also showed intermediate susceptibility to norfloxacin and chloramphenicol, and HD51 showed intermediate susceptibility to vancomycin and nalidixic acid. Targeted PCR assay confirmed the absence of the screened genes associated with antibiotic resistance and virulence factors. Further, the strains HD48 and HD51 did not cause any significant (P > 0.05) changes in cell viability of Caco-2 cells as determined by the MTT assay (95%-99%). In conclusion, the results indicate a favourable in vitro safety profile of Lpb. plantarum HD48 and HD51. Therefore may be potentially suitable for a range of food applications and collectively these findings suggest that Lactiplantibacillus plantarum HD51 and HD48 are safe for use and warrant further validation through in vivo studies in both healthy and diseased models.

This study developed a natural polymer-based microencapsulation system for Lactiplantibacillus plantarum HD51 using alginate, skimmed milk and flaxseed mucilage. Four formulations were evaluated for encapsulation efficiency, gastrointestinal survivability, release behaviour, exopolysaccharide production, antimicrobial activity, storage stability and pancreatic lipase inhibitory potential. The composite matrix (Alg–SM–FM) achieved the highest encapsulation efficiency (95.54%) and exhibited improved protection of probiotic cells under simulated gastric and intestinal conditions compared with single-component systems. Scanning electron microscopy revealed a denser and more compact microstructure in composite formulations, indicating enhanced physical protection. Encapsulated probiotics maintained viable counts above 10 ⁷ CFU/g, showed controlled release in simulated intestinal fluid and retained antimicrobial activity and exopolysaccharide-producing capability. Multivariate analysis using principal component analysis revealed clear associations between formulation composition and key functional attributes, including encapsulation efficiency, bead size, survivability and bioactivity. Additionally, encapsulated Lactiplantibacillus plantarum HD51 demonstrated measurable pancreatic lipase inhibitory activity, suggesting potential relevance for metabolic health applications. Overall, the results indicate that combining alginate with dairy- and plant-derived biopolymers provides a promising food-grade strategy for enhancing probiotic stability and functionality in functional food and nutraceutical applications.

Background: Natural preservatives are of immense importance to meet the rising demand for food with either little or no synthetic preservatives. This study has evaluated the inhibitory effect of cinnamaldehyde, citral and eugenol essential oil (EO) against mold growth on solid media and cheese in the vapour phase and contact treatments. Methods: The effect of EO at concentrations ranging from 0.06 to 0.25 µl/ml on radial growth of molds was examined. Further, the antifungal properties of vapors of EOs formulated into edible films at 1 to 5% were investigated using the microatmosphere method. Result: The application of EOs directly on the surface of cheese at 0.03 mg/cm2 caused the irreversible inhibition of molds as compared to the control. Both A. flavus and A. niger were sensitive to EO in contact treatments, but there was no significant difference between different EOs after 6 days. According to the results of vapour phase diffusion test cinnamaldehyde significantly suppressed the growth of A. flavus and A. niger on the solid medium and cheese surface at 25°C for 7 days storage. These findings suggest that constituents of EOs could be used as a possible substitute for antifungal chemicals to control mold growth on cheese.

Essential oils as a whole have been widely investigated for their antimicrobial properties against spoilage microorganisms and pathogens. However limited information is available about the inhibitory activities of components of EO in foods and more specifically in dairy food matrices. The widespread components of common EOs were evaluated for their antibacterial activity in media and skim milk. Amongst the components, trans-cinnamaldehyde and eugenol were the most effective with minimum bactericidal concentrations of 4 mg/ml and 12 mg/ml, respectively in milk. The trans-cinnamaldehyde had the lowest MBC of 10 mg/g in paneer slurry against L. monocytogenes and E. coli O157:H7. The microbial load in paneer made from EO added to milk (1%) significantly inhibited microbial growth during storage. In the dairy spread, trans-cinnamaldehyde and eugenol were effective in inhibiting TBC, coliform, and yeast & mold count at 0.25 mg/ml without affecting sensory properties.

Bovine mastitis has become a significant economic importance for dairy industry. Concerns regarding poor milk quality, and emergence of bacterial resistance has necessitated to develop alternative therapeutic approach to antibiotics for treatment of mastitis. Saturated medium-chain fatty acids (MCFAs) and essential oils (EOs) are known natural antimicrobials, but their combined effect has not been investigated extensively. The objective of the present investigation was to examine the bactericidal effect of various combined treatments of eight EOs and three saturated MCFAs to inactivate predominant mastitis pathogens, including Staphylococcus aureus ATCC 29213; Escherichia coli ATCC 25922; Klebsiella pneumoniae ATCC 27736; and Streptococcus agalactiae ATCC 27956. The minimum inhibition concentration (MIC) values confirmed that all the tested pathogens were variably susceptible to both EOs and saturated MCFAs. Among essential oils, carvacrol (CAR), trans-cinnamaldehyde (TC), and thymol (TM) showed highest inhibitory activity at concentration 0.38-1.32 mg/mL. Carvacrol exhibited effective additive antibacterial activity in combined treatment with octanoic acid (OA) in terms of its fractional inhibitory index (0.63-0.88) and time-kill effect in reducing about 6 log CFU/mL bacterial cells in less than 5 min. Effort was also made to elucidate mechanism of antibacterial action of CAR and OA against selected mastitis pathogens by observing changes in cell microstructure, permeability and integrity of cell membrane and their membrane potential. After adding CAR and OA at MIC level, there were obvious changes in cell morphology, leakage of small electrolytes, and macromolecules at the initial few hours of treatment i.e. within 1-2 h were observed. Our results indicated that CAR and OA could be evaluated as alternatives or adjuncts to antibiotics as intramammary infusion or topical application to treat bovine mastitis, significantly improving the microbiological safety of milk.

The aim of present study was to assess the potentials of enhancing the inhibitory effect of combined application of cinnamaldehyde, eugenol and citral on the growth of food spoilage yeasts using fractional inhibitory concentration (FIC) index in laboratory media and time-kill assay in a food model. The minimum inhibitory concentrations (MIC) of cinnamaldehyde, eugenol and citral were 0.125, 0.5 and 0.5 mu L/mL, respectively. The FIC indices of combinations assessed showed that cinnamaldehyde and citral combination exhibit synergistic interaction and no difference were found among other combinations tested. The combined effect observed was validated in skimmed milk and Lassi against the most common yeast Saccharomyces cerevisiae. The tested combination demonstrated stronger anti-yeast activity by completely inhibiting of the growth when compared to control. These results demonstrated potential of green chemistry as an alternate to chemical preservative to prevent yeast spoilage of milk and fermented milk products could be used as valuable additives to improve microbiological stability of dairy products and meet expectations of consumers.

This research paper is based upon the production, purification and characterization of bacteriocin by L.pentosusMW857478 followed by its enhancement of food safety and shelf life of paneer. In recent year LAB (Lactic acid bacteria) produced bacteriocinattract a great attention of researcher due to their many potential applications. This paper focused on isolation, identification, evaluation of broad spectrum inhibitory activity, production and purification, characterization and evaluation of food safety and shelf life of paneer. Bcateriocin produced byL. pentosusshowedantagonistic activity against food spoiling pathogens in broad range ofBacteriocin production parameter was optimized with pH 5.5 incubated at 35°C forL. pentosus. Bacteriocin was purified by ammonium sulphate precipitation and purified bacteriocin with single band on SDS-PAGE for molecular weight. The purified bacteriocin stableat 2-10 pH and 30-75°C temperatures, suggesting L. pentosusa potent candidates for safety and extending shelf life of paneer for 15 days.

In the present investigation, we determined the in vitro antimicrobial activity of eight essential oils (EOs) and three medium-chain fatty acids (MCFAs) alone and in combination against Staphylococcus aureus ATCC 700698, Klebsiella pneumoniae ATCC 700603, and E. coli FcW5. The interactions between EOs and MCFAs were determined by fractional inhibitory concentration indices. Moreover, mode of action of selected bioactive components was studied by changes in bacterial surface charge, morphology, and membrane integrity assays. Among EOs, carvacrol (CAR), trans-cinnamaldehyde (TC), and thymol (TM) showed strong antimicrobial activity. In combination study, CAR+OA (octanoic acid), CAR+DA (decanoic acid), and TM+OA were observed as the most significant (P≤0.05) which were also confirmed through time-kill plots. Based on these results, CAR+OA were found to be most efficacious in terms of killing time (P≤0.05). Changes in the surface charge, morphology, and membrane integrity upon the combined treatment of CAR+OA were also observed, which ultimately leads to cell death. Results suggest that CAR+OA when used in combination offer a significant (P≤0.05) additive antimicrobial activity against the selected pathogenic bacteria. Therefore, these natural bioactive molecules could be interesting alternatives to conventional therapy for the control of mastitis caused by multi-drug-resistant pathogens in bovine animals to ensure the milk safety.