Nguyen Bao Loc * , Nicorescu Irina and Orange Nicole

* Corresponding author (nbloc@ctu.edu.vn)

Abstract

In this work, pulsed light (PL) efficacy was investigated on B. subtilis spores in liquid and dry state (glass marbles and spices). We studied the bacterial suspension in conditions (0.6 J.cm-2/flash) and spices at 1 J.cm-2/flash. In liquid state, only 0.9 log microbial reduction was recorded when 6 J.cm-2 was applied. SEM analysis showed that B. subtilis spores in suspension were not affected by the PL treatment. When DNA extracted from B. subtilis spores was analyzed, no significant difference was found between the control and PL-treated samples. In dry state the destruction level remained below 1 log when a treatment of 10 J.cm-2 was carried out on black pepper and ground caraway, while a 2.8 log microbial reduction was reached for glass marbles. When control and PL-treated B. subtilis spores in dry state were investigated by SEM, no disruption in spore structure was recorded but a significant number of PL-treated spores were flattened.

Keywords: Pulsed light, spices, decontamination, Bacillus subtilis spore

Tóm tắt

Trong nghiên cứu này, hiệu quả diệt khuẩn của xung ánh sáng được đánh giá trên bào tử Bacillus subtilis dạng huyền phù và dạng khô (bào tử vi khuẩn được gây nhiễm trên bi thuỷ tinh và gia vị). Nghiên cứu được thực hiện với cường độ 0,6 J.cm-2/xung trên huyền phù vi sinh vật, và trên gia vị với cường độ 1 J.cm-2/xung. ở dạng huyền phù, với cường độ 6 J.cm-2 chỉ tiêu diệt được 0,9 log bào tử vi khuẩn.Hình ảnh phân tích bằng kính hiển vi điện tử (SEM) cho thấy bào tử B.subtilis ở dạng huyền phù không bị ảnh hưởng bởi xử lý xung ánh sáng. Qua phân tích ADN trích ly từ bào tử B subtilis,không nhận thấy sự khác biệt ý nghĩa giữa mẫu xử lý và mẫu đối chứng. ở dạng khô, mức độ tiêu diệt bào tử B. subtilis đạt được dưới 1 log khi xử lý ở cường độ 10 J.cm-2 trên hạt tiêu và tiểu hồi, trong khi trên bi thuỷ tinh thì mức độ này đạt tới 2,8 log.Khi phân tích hình ảnh bào tử B. subtilis dạng khô của mẫu đối chứng và mẫu xử lý bằng xung ánh sáng qua kính hiển vi điện tử, các bào tử đều không bị phá vỡ bởi xung ánh sáng, tuy nhiên có một số lượng đáng kể bào tử bị thay đổi hình dạng được phát hiện trong mẫu đã xử lý bằng xung ánh sáng.

Từ khóa: xung Ánh sáng, gia vị, khử nhiễm, bào tử B. subtilis

Article Details

References

Anderson, J. G., Rowan, N. J., MacGregor, S. T., Fouracre, R. A., & Farish, O. (2000). Inactivation of food-borne enteropathogenic bacteria and spoilage fungi using pulsed-light. IEEE Transactions on Plasma Science, 28, 83–88.

Bushnell, A., Cooper, J. R., Dunn, J., Leo, F., & May, R.(1998). Pulsed light sterilization tunnels and sterile-pass-throughs. Pharmaceutical Engineering, March/April, 48–58.

Dunn, J., Clark, R., & Ott, T. (1995). Pulsed-light treatment of food and packaging. Food Technology, 49,95–98.

Elmnasser, N., Guillou, S., Leroi, F., Orange, N., Bakhrouf, A., & Federighi, M. (2007). Pulsed-light system as a novel food decontamination technology: A review. Canadian Journal of Microbiology, 53,813–821.

Farkas, J. (2007) Physical methods of food preservation. In: Doyle, M.P., Beuchat, L.R. (Eds.), Food Microbiology: Fundamentals and Frontiers. ASM Press, Washington pp. 685–712.

Farrell, H., Hayes, J., Laffey, J., & Rowan, N. (2011). Studies on the relationship between pulsed UV light irradiation and the simultaneous occurrence of molecular and cellular damage in clinically-relevant Candida albicans. Journal of Microbiological methods, 84, 317 – 326.

Feuilloley, M. G. R., Bourdet, G., & Orange, N.(2006). Effect of white pulsed light on Pseudomonas aeruginosaculturability and its endotoxin when present in ampoules for injectables. European Journal of Parenteral and Pharmaceutical Science, 11,9–14.

Fine, F., & Gervais, P. (2005). Efficiency of pulsed UV light for microbial decontamination of food powders. Journal of Food Protection, 67,787–792.

Gardner, D. W. M., & Shama, G. (1998). The kinetics of Bacillus subtilisspore inactivation on filter paper by UV light and UV light in combination with hydrogen peroxide. Journal of Applied Microbiology, 84,633–641.

Gómez-López, V. M., Devlieghere, F., Bonduelle, V., & Debevere, J. (2005). Intense light pulses decontamination of minimally processed vegetables and their shelf-life. International Journal of Food Microbiology, 103,79–89.

Harm, W. (1980). Repair related phenomena. In W. Harm, (Eds.), Biological Effects of Ultraviolet Radiation(pp. 124-134). Cambridge: Cambridge University Press.

Jun, S., Irudayaraj, J., Demirci, A., & Geiser, D. (2003). Pulsed UV-light treatment of corn meal for inactivation of Aspergillus nigerspores. International Journal of Food Science and Technology, 38,883–888.

Keith, W. D. (1998). Microbial reduction in flour and spice using pulsed electric fields (pp. 22-24). phD thesis (in English). University of Guelph, Canada.

Kramer, J. M., & Gilbert, R. J. (1989). Bacillus cereusand other Bacillusspecies. InM. P. Doyle (Ed.) Foodborne Bacterial Pathogens. Marcel Dekker, New York, NY, pp. 21–70.

Lagunas-Solar, M. C., Pina, C., MacDonald, J. D., & Bolkan, L.(2006). Development of pulsed UV light processes for surface fungal desinfection of fresh fruits. Journal of Food Protection, 69, 376–384.

Levy, C., Bornard, I., & Carlin, F. (2011). Deposition of B. subtilisspores using an airbrush-spray or spots to study surface decontamination by pulsed light. Journal of Microbiological Methods, 84,223–227.

Levy, C., Aubert X., Lacour B., & Carlin, F. (2012) Relevant factors affecting microbial surface decontamination by pulsed light. International Journal of Food Microbiology,152, 168–174.

Massier, S., Rincé, A., Maillot, O., Feuilloley, M. G. J., Orange, N., & Chevalier, S. (2011). Adaptation of Pseudomonas aeruginosato a pulsed light-induced stress. Journal of Applied Microbiology, 112, 502–511.

McDonald, K. F., Curry, R. D., Clevenger, T. E., Unklesbay, K., Eisensstark, A., Golden, J., & Morgen, R. D.(2000). A comparison of pulsed and continuous ultraviolet light sources for the decontamination of surfaces. IEEE Transactions on Plasma Science, 28,1581–1587.

McKee, L. H. (1995). Microbial contamination of spices and herbs: A review. Lebensmittel-Wissenschaft und-Technologie, 28,1–11.

Mitchell, D. L., Jen, J., & Cleaver, J. E.(1992). Sequence specificity of cyclobutane pyrimidine dimers in DNA treated solar (ultra-violet B) radiation. Nucleic Acids Research, 20,225–229.

Nicorescu I., Nguyen B., Moreau-Ferret M, Agoulon A., Chevalier S., & Orange N. (2013) Pulsed light inactivation of Bacillus subtilis vegetative cells in suspensions and spices. Food Control,31, 151–157.

Ozen, B.F., & Floros, J.D., (2001) Effects of emerging food processing techniques on the packaging materials. Trends in Food Science & Technology, 12, 60–67.

Ozer, N. P., & Demirci, A. (2006). Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated on raw salmon filets by pulsed UV-light treatment. International Journal of Food Science and Technology, 41,354–360.

Palgan I., Caminiti I. M., Munoz A., Noci F., Whyte P., Morgan D. J., Cronin D. A., & Lyng J. G. (2011) Effectiveness of High Intensity Light Pulses (HILP) treatments for the control of Escherichia coliand Listeria innocuain apple juice, orange juice and milk. Food Microbiology, 28, 14–20.

Rajkovic, A., Tomasevic, I., Smigic, N., Uyttendaele, M., Radovanovic, R., & Devlieghere, F.(2010) Pulsed UV light as an intervention strategy against Listeria monocytogenesand Escherichia coliO157:H7 on the surface of a meat slicing knife. Journal of Food Engineering, 100, 446–451.

Ramos-Villarroel, A. Y., Aron-Maftei N., Martin-Belloso O., & Soliva-Fortuny, R. (2012). Influence of spectral distribution on bacterial inactivation and quality changes of fresh-cut watermelon treated with intense light pulses. Postharvest Biology and Technology, 69, 32–39.

Riesenman, P. J., & Nicholson, W. L. (2000). Role of the spore coat layers in Bacillus subtilis spore resistance to hydrogen peroxide, artificial UV-C, UV-B, and solar UV radiation. Applied and Environmental Microbiology, 66, 620–626.

Setlow, B., & Setlow, P. (1987). Thymine-containing dimers as well as spore photoproducts are found in ultraviolet-irradiated Bacillus subtilisspores that lack small acid-soluble proteins. Proceedings of the National Academy of Science, USA, 84, 421–423.

Setlow, B., & Setlow, P. (1998). Heat killing of Bacillus subtilisspores in water is not due to oxidative damage. Applied and Environmental Microbiology, 64, 4109–4112.

Sharma, R. R., & Demirci, A., (2003) Inactivation of Escherichia coli O157: H7 on inoculated alfalfa seeds with pulsed ultraviolet light and response surface modeling. Journal of Food Science, 68, 1448–1453.

Sonenshein, A. L. (2003). Killing of Bacillus spores by high-intensity ultraviolet light. In Sterilization and decontamination using high-energy light. Xenon Corporation, Woburn, Mass., pp. 15–19.

Staack, N., Ahrné, L., Borch, E., & Knorr, D. (2008). Effect of infrared heating on quality and microbial decontamination in paprika powder. Journal of Food Engineering, 86,17–24.

Takeshita, K., Shibato, J., Sameshima, T., Fukunaga, S., Isobe, S., Arihara, K., & Itoh, M. (2003). Damage of yeast cells induced by pulsed light irradiation. International Journal of Food Microbiology, 85,151–158.

Turtoi, M., & Nicolau, A., 2007. Intense light pulse treatment as alternative method for mould spores destruction on paper-polyethylene packaging material. Journal of Food Engineering, 83, 47–53.

Wekhof, A. (2000). Desinfection with flash lamps. PDA Journal of Pharmaceutical Science and Technology, 54, 264–276.

Wekhof, A. (2001). Pulsed UV disintegration (PUVD): a new sterilisation mechanism for packaging and broad medical-hospital applications. The First International Conference on Ultraviolet Technologies, 14 – 16 June, Washington D.C., USA.

Wekhof, A. (2003). Sterilisation of packaged pharmaceutical solutions, packaging and surgical tools with pulsed light. The 2nd International Congress on Ultraviolet Technologies, 9 – 11 July, Vienna, Austria.