Iranian Journal of

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Background and Objective: Milk and milk products are very suitable medium for growing microorganisms (e.g. Bacillus cereus). B. cereus is spore former bacilli, which easily survives during pasteurization and makes several problems in dairy industries. The aim of this study was to investigate aerobic spore and B. cereus of receiving raw milk from three UF plants. Materials and Methods: Samples were gathered from raw milk transport tankers arrived to plants during 30 days in winter. Also, the swab test was used for detection of B.cereus residual on milk contact surfaces. Results: High contamination level of aerobic spores (AeSC) and especially B.cereus were found in most samples compared with the criteria established by national and international standards. Although total viable count (TVC) in samples from industrial farms (IF) was lower than those from traditional farms (TFs) and milk collection centers (MCCs), considerable AeSC and B.cereus were transmitted to the UF plants from IFs. The highest and lowest TVC and B.cereus were found in samples from IFs and MCCs, respectively. In addition, our investigation in IFs revealed that teats contamination to soil and feces, as well as contaminated bedding might were the most important sources of B. cereus and AeSC of raw milk. Moreover, the results of swab tests confirmed that the “cleaning in place” system may not remove B.cereus effectively. Conclusion: It seems that for classifying raw milk quality, AeSC might be used as a more effective quality factor than TVC. Management commitment is effective to improve quality by balance between the amount and quality of receiving raw milk. This leads to the lower contamination in dairy plants and final products.

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Background & Objectives: Cryptosporidium parvum is considered as one of the pathogenic agents transmitted by water, high resistance to conventional disinfection methods, and potency of creating various problems in water resource. Because of various problems in Cryptosporidium parvum studies, Bacillus subtilis spore is recommended as a surrogate organism for studying protozoa inactivation and evaluation of water quality. On the other hand, electrochemical process is presented as an environmental friendly and high efficient method in disinfection in recent years. The aim of this study was to propose a method for promotion of the water quality. Materials & Methods: In this study, the electrochemical system used was consisted of steel electrodes (4×8 cm), 200 mL volume, and 1-4 mg/L sodium chloride. The bacterial suspensions of Bacillus subtilis (ATCC 6633) was prepared according to the McFarland method with 103 to 106 spores/mL concentration. The microbial agent removal was evaluated by sampling and transferring water to the tripticase soy agar medium every 15 min for 60 min. The number of bacteria spores, supporting electrolyte, induced current, and reaction time were evaluated. Results: The proposed electrolysis process could not eliminate Bacillus subtilis spores at 104 to 106 spores mL^-1 rate at lower than 100 mA current for 60 min. Adding sodium chloride supporting electrolyte up to 4 mg/L concentration completely eliminated Bacillus subtilis spores after 60 min. Conclusion: Adding sodium chloride as a supporting electrolyte can increase the spore removal because of increasing direct and indirect oxidation in electrolysis process. Improving water disinfection and spore removal after 60 min could be described by higher oxidant agents in anode electrode.

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Background and Objectives: Considering the complexity, cost, and time-consuming techniques of detecting Cryptosporidium oocysts and Giardia cysts,  B. subtilits spores have been introduced as microbial indicators of these pathogens to evaluate the efficacy of disinfection studies. The present study was aimed to investigate the feasibility of B. subtilis spores inactivation using hydrogen peroxide combined with copper and silver ions. A new glutaraldehyde based compound used for surface disinfection was also tested.

Materials and Methods: In order to sporulation, vegetative bacteria were allowed to grow on a medium with insufficient nutrients, and after 5 days incubation at 37˚C, spores were washed and purified. Spore suspension was used to prepare synthetic water. Disinfection efficiency was reported as logarithmic decrease of initial spore count.

Results: This research found that none of the disinfection compounds was able to spore inactivation in low initial concentration. The highest spore reduction efficiency was related to HP/Cu⁺² with 1.48 log inactivation, and HP/Ag⁺ compound placed in the second rank with 1.03 log reduction. Maximum spore reduction of 0.6 log was achieved when glutaraldehyde based disinfectant was used in disinfection process.

Conclusion: According to the results, it can be concluded that spores are very resistant even to combination of disinfectants. Spore reduction potential of the studied compounds was as follows: HP/Cu⁺²> HP/Ag⁺> glutaraldehyde based compound.