Spore-forming Anaerobe Research Articles

Aerobic deterioration stimulates outgrowth of spore-forming Paenibacillus in corn silage stored under oxygen-barrier or polyethylene films

The occurrence of Bacillus and Paenibacillus spores in silage is of great concern to dairy producers because their spores can survive pasteurization and some strains are capable of subsequently germinating and growing under refrigerated conditions in pasteurized milk. The objectives of this study were to verify the role of aerobic deterioration of corn silage on the proliferation of Paenibacillus spores and to evaluate the efficacy of oxygen-barrier films used to cover silage during fermentation and storage to mitigate these undesirable bacterial outbreaks. The trial was carried out on whole-crop maize (Zea mays L.) inoculated with a mixture of Lactobacillus buchneri, Lactobacillus plantarum, and Enterococcus faecium. A standard polyethylene film and a polyethylene-polyamide film with an enhanced oxygen barrier were used to produce the silage bags for this experiment. The silos were stored indoors at ambient temperature (18 to 22°C) and opened after 110 d. The silage was sampled after 0, 2, 5, 7, 9, and 14 d of aerobic exposure to quantify the growth of endospore-forming bacteria during the exposure of silages to air. Paenibacillus macerans (gram-positive, facultatively anaerobic bacteria) was able to develop during the aerobic exposure of corn silage. This species was present in the herbage at harvesting, together with clostridial spores, and survived ensiling fermentation; it constituted more than 60% of the anaerobic spore formers at silage opening. During silage spoilage, the spore concentration of P. macerans increased to values greater than 7.0 log10 cfu/g of silage. The use of different plastic films to seal silages affected the growth of P. macerans and the number of spores during aerobic exposure of silages. These results indicate that the number of Paenibacillus spores could greatly increase in silage after exposure to air, and that oxygen-barrier films could help to reduce the potential for silage contamination of this important group of milk spoilage microorganisms by delaying the onset of aerobic deterioration.

Is the microbiological quality of the Msunduzi River (KwaZulu-Natal, South Africa) suitable for domestic, recreational, and agricultural purposes?

As little is known about the potential risks associated with the use of microbiologically contaminated river water for recreation, irrigation, or domestic purposes, the Msunduzi River in Pietermaritzburg (KwaZulu-Natal, South Africa) was evaluated. In addition to pH, temperature, and chemical oxygen demand, quantitative and qualitative microbiological analyses were performed monthly for 13months. These included aerobic plate counts, counts of aerobic and anaerobic sporeformers, most probable numbers for total and faecal coliforms and Escherichia coli and the detection of Salmonella spp., Staphylococcus aureus, and intestinal enterococci. Presumptive E. coli and S. aureus from river water samples were confirmed using PCR and additionally matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS) for E. coli. Aerobic plate counts were above the South African Department of Water Affairs recommended guideline level for domestic use of 100cfu/ml for all 13months assessed. Faecal coliform (up to 63,000 MPN/100ml) and E. coli (up to 7,900 MPN/100ml) levels regularly exceeded stipulated limits for safe irrigation, domestic and recreational use. The presence of Salmonella spp., S. aureus, and intestinal enterococci frequently coincided with faecal coliform and E. coli levels above 1,000MPN/100ml. This illustrates the value of using guideline values for faecal coliforms and E. coli as indicators for the presence of potential pathogens. PCR and MALDI-TOF MS confirmation of E. coli were in agreement, thereby demonstrating the potential of MALDI-TOF MS as a suitable alternative. These data demonstrate that potential health risks are associated with using Msunduzi River water for irrigation and recreational or domestic purposes.

Silage and the safety and quality of dairy foods: a review

Silage contains a number of potential hazards to the safety and quality of milk and dairy products. This paper reviews the present knowledge about silage as a source of (1) spores of anaerobic spore-formers (Clostridium species) and aerobic spore-formers (mainly Bacillus and Paenibacillus species), (2) the zoonotic pathogenic bacteria Listeria monocytogenes and Escherichia coli, and (3) mycotoxins. A distinction is made between field-derived mycotoxins, i.e. mycotoxins that are formed during growth of crops in the field, and ensilage-derived mycotoxins, i.e. mycotoxins that are formed after ensiling. The routes of transmission of these hazards from feed to milk, the effect of pasteurization of milk, and reduction strategies are discussed. Aerobic deterioration of silages is a major factor influencing levels of spores of both aerobic and anaerobic spore-formers, L. monocytogenes, and certain mycotoxins.

The microbiological profile of Jamaican Ackees (Blighia sapida)

PurposeThe aim of this paper is to study the microbiological profile of the ackee fruit during maturation.Design/methodology/approachAckees at ripening stage five, mature but unopened, were allowed to ripen naturally on the trees or on ripening racks used in commercial processing. The microbiological profile of fruits from this stage to that where they had ripened to the point just prior to decay (stage ten) were assessed. Aerobic and anaerobic mesophilic and thermophilic sporeformers and vegetative cells, total coliforms, E. coli, lactic acid bacteria, yeasts and molds at each stage were determined using standard methods.FindingsThe number of microorganisms on the tree‐ripened fruits was higher than those ripened on racks. Mesophilic aerobic and anaerobic spore‐forming organisms were present in greater numbers than thermophiles at all stages of maturity. Coliforms, excluding E. coli, were found on the tree‐ripened ackees particularly in the latter stages of ripening. Lactic acid bacteria and yeasts and molds found on both tree and rack‐ripened fruit may be the predominant agents in the microbiological spoilage of ackees during ripening.Originality/valueThis study is the first to assess the microbiological profile of ackees during ripening. It indicated that the relatively low levels of microorganisms of economic or public health significance during both tree‐ and rack‐ripening processes would not affect the commercial sterility of the canned product, even with a moderate thermal process (Fo of 3). It also suggests that controlled rack‐ripening of ackee fruit during commercial processing could improve the microbial quality of the processed product.

Food borne bacteria isolated from spices and fate of Cronobacter sakazakii ATCC 29544 in black pepper exposed to drying and various temperature conditions

Food-borne disease outbreaks caused by spices have been on the increase in the recent years, although they are rarely reported in the developing countries. The purpose of this work therefore, is to show that spices sold in selected retail outlets in Durban South Africa may contain unacceptable level of pathogenic microorganisms including Cronobacter sakazakii which may survive desiccation and high temperature. Selected spices were purchased from four retail outlets in Durban and examined for the presence of aerobic bacteria (AB), aerobic sporeformers (ASF), anaerobic sporeformers (AnSF),Staphylococcus aureus and C. sakazakii using ISO methods. Black pepper was inoculated with 108 cfu/ml of C. sakazakii ATCC 29544 and subjected to pasteurization temperature, desiccation temperature and they were later stored in refrigeration and room temperatures for 72 h. The mean values of AB, ASF, AnSF and S. aureus in the sampled spices were 2.98, 3.05, 1.82 and 1.67 log cfu/g, respectively; however analysis of variance showed that S. aureus was significantly low in cinnamon as compared to other spices. C. sakazakii was recovered in 50% of the samples tested. The result of the impact of processing temperature on black pepper inoculated with C. sakazakii ATCC 29544 showed that pasteurization at 72°C for 15 s was unable to eradicate all the pathogens. Desiccation (58°C for 50 min) combined with low temperature storage however was able to eliminate the pathogen. The sampled spices constitute a public health risk and C. sakazakii ATCC 29544 was able to survive high temperature such as pasteurization. Also, spices contaminated with CS may still grow after desiccation if stored at room temperature. Key words: Bacteria, pathogens, Cronobacter sakazaki, temperature, desiccation.

Microbiological and Marine Biotoxins Contamination of Raw Bivalve Molluscs Commercially Available in Poland

Abstract The study was carried out on live bivalve molluscs available on Polish market. Microbiological tests were performed for the presence of Salmonella sp., Vibrio parahaemolyticus, spore-forming anaerobe bacteria, and coagulase-positive Staphylococcus sp., and for the enumeration of Escherichia coli. ELISA was used for the determination of marine biotoxins, paralytic shellfish poisoning (PSP), amnesic shellfish poisoning (ASP), and diarrhoeic shellfish poisoning (DSP). Microbiological examinations were performed according to ISO and Polish Standards. Salmonella sp. was not detected in any sample tested. Coagulase-positive staphylococci were identified in 9.0% of the samples. V. parahaemolyticus was isolated from 17.0% of mussels. Shellfish were highly contaminated by anaerobes, which were isolated from 68.0% of the samples. The number of E. coli ranged from <2.0 x 101 up to >1.8 x 104 MPN/100 g. The majority of mussels were free from the marine biotoxins tested or contained them bellow the permitted level. The analysis of microbiological and toxicological status of raw bivalve molluscs available on Polish market indicates that they are generally safe for the consumers.

차단성 다층 트레이에 포장된 레토르트 닭 가슴살제품의 냉장 중 품질 특성

Ready-to-eat chicken breasts were packaged in a multilayer, gas-tight tray with top film and various quality changes were investigated during the 24 wk of storage at 10 o C. Over the storage period, total aerobes, mesophilic aerobic and anaerobic spore formers, and Clostridium spp. were not detected above 1.0 log CFU/g (detection limit). The residual oxygen ratio in the head space of tray and pH values tended to decrease with storage time, namely from initial values of 5.7% and 6.56 to 3.3% and 6.34 at week 24, respectively. Thiobarbituric acid reactive substances and volatile basic nitrogen values increased from 0.52 mg malonaldehyde (MA)/kg and 2.1 mg/100 g initially, to 3.70 mg MA/kg and 39.9 mg/100 g at week 24, respectively. In terms of the change in meat color during storage, the samples showed a slight increasing trend of CIE a * , b * , and ∆E values over the storage period until week 24 (p<0.05). The change in brine color showed a similar trend with meat of which Hunter b * and ∆E values increased slightly during storage during 24 wk (p<0.05). The values for the transmittance degree of brine in the samples tended to decrease. Moreover, values for the absorbance degree tended to increase with storage time until week 24. The sensory scores for color, texture, odour, and flavour were evaluated below 5.0 (marketability level) after 24 wk of storage. Based on this sensory evaluation, it could be concluded that retorted RTE chicken breast could remain marketable for at least 20 wk at 10 o C.

CHEMICAL AND MICROBIOLOGICAL EVALUATION OF SOME FISH PRODUCTS SAMPLES

Different kinds of fish products namely canned, salted, smoked, and frozen fish were collected from local markets in Damietta Governorate. The aim of this study was to report if these fish products were in compatible with Egyptian standard specifications or not. Subsequently, be ensure that these fish products highly consumed in Damietta Governorate were safe foods for human or not. Total viable bacterial count, aerobic spore forming bacteria, Staphylococcus aureus, coliform group, Clostridium spp. and anaerobic spore formers producing H2S were studied. Finally, from the obtained results it could be reported that all studied fish products were compatible with their standard specifications from chemical and microbiological view except salted fish products (salted sardine and salted mullet named Feseikh) did not agree with their standard specification from microbiological aspects and may be harmful for consumers.

Efficient Isolation and Identification of Bacillus cereus Group

Bacillus cereus is a group of ubiquitous facultative anaerobic sporeforming Gram-positive rods commonly found in soil. The spores frequently contaminate a variety of foods, including produce, meat, eggs, and dairy products. Foodborne illnesses associated with toxins produced by B. cereus can result in self-limiting diarrhea or vomiting. Plate enumeration methods recommended by recognized food authorities to detect the presence of B. cereus in potentially contaminated food products do not inhibit other Gram-positive competitive bacteria. This study evaluated the use of Bacara, a new chromogenic agar, as an efficient method to identify and enumerate B. cereus group from food matrixes, even in the presence of background flora. Inclusivity and exclusivity testing was performed using four different selective and differential media for B. cereus, including Mannitol Egg Yolk Polymyxin (MYP), Polymyxin Pyruvate Egg-Yolk Mannitol Bromothymol Blue Agar, Bacillus Chromogenic Media, Brilliance, and Bacara. MYP and Bacara were also used in plate enumeration studies to isolate B. cereus from artificially contaminated foods.

IRRIGATION WATER AS A POTENTIAL PREHARVEST SOURCE OF BACTERIAL CONTAMINATION OF VEGETABLES

ABSTRACT The aim of this research is to determine the bacteriological quality of the irrigation canal from Loskopdam, the two rivers that feed it and vegetables (broccoli and cauliflower) in Mpumalanga, South Africa and also to predict the presence of selected bacterial pathogens in irrigation water and on vegetables with logistic regression analysis. Water and vegetable samples were examined for the presence of total coliforms, fecal coliforms, Escherichia coli, Listeria monocytogenes, Salmonella sp., Enterococcus, Staphylococcus aureus, aerobic spore formers, anaerobic spore formers and aerobic colony counts were done. Apart from bacterial analysis, the following physicochemical tests: temperature, pH, turbidity and chemical oxygen demand (COD) were determined in water samples. The average COD and turbidity in the two rivers and the canal were higher than the World health Organization (WHO) and South African water guidelines. Sampling and analyses were done for a period of 12 months. Levels of fecal coliforms and E. coli were higher than the WHO standard. S. aureus, intestinal enterococci, Salmonella, L. monocytogenes were recovered from the two rivers and the canal. Apart from L. monocytogenes, which was not recovered from cauliflower, all bacterial pathogens recovered from the surface water were recovered from the vegetables. PRACTICAL APPLICATION These results show that the rivers in Mpumalanga may contribute to the contamination in the irrigation canal which may be a possible preharvest source of contamination of broccoli and cauliflower, which may in turn constitute a health risk to consumers. Logistic regression analysis of the sampled data showed that chemical oxygen demand was statistically reliable to predict Listeria monocytogenes, turbidity reliable to predict intestinal enterococci and fecal coliform and coliform reliable to predict Salmonella in irrigation water. Aerobic colony count was statistically significant for the prediction of the three pathogens in vegetables.

Comparative genomic and transcriptomic analysis revealed genetic characteristics related to solvent formation and xylose utilization in Clostridium acetobutylicum EA 2018

BackgroundClostridium acetobutylicum, a gram-positive and spore-forming anaerobe, is a major strain for the fermentative production of acetone, butanol and ethanol. But a previously isolated hyper-butanol producing strain C. acetobutylicum EA 2018 does not produce spores and has greater capability of solvent production, especially for butanol, than the type strain C. acetobutylicum ATCC 824.ResultsComplete genome of C. acetobutylicum EA 2018 was sequenced using Roche 454 pyrosequencing. Genomic comparison with ATCC 824 identified many variations which may contribute to the hyper-butanol producing characteristics in the EA 2018 strain, including a total of 46 deletion sites and 26 insertion sites. In addition, transcriptomic profiling of gene expression in EA 2018 relative to that of ATCC824 revealed expression-level changes of several key genes related to solvent formation. For example, spo0A and adhEII have higher expression level, and most of the acid formation related genes have lower expression level in EA 2018. Interestingly, the results also showed that the variation in CEA_G2622 (CAC2613 in ATCC 824), a putative transcriptional regulator involved in xylose utilization, might accelerate utilization of substrate xylose.ConclusionsComparative analysis of C. acetobutylicum hyper-butanol producing strain EA 2018 and type strain ATCC 824 at both genomic and transcriptomic levels, for the first time, provides molecular-level understanding of non-sporulation, higher solvent production and enhanced xylose utilization in the mutant EA 2018. The information could be valuable for further genetic modification of C. acetobutylicum for more effective butanol production.

Quality of chilled ready-to-bake pizza stored in air and under modified atmospheres: Microbiological and sensory attributes

Modified atmosphere packaging (MAP) studies on microbiological and sensory analysis were conducted to extend the shelf life of ready-to-bake pizza stored at 7±1°C. The gas combinations used were: atm1: air (control), atm2: CO2 (100%), atm3: N2 (100%), atm4: 50% CO2/50% N2. Total plate count (TPC), yeasts/molds (Y/M), coliforms, lactic acid bacteria (LAB), psychrotrophs, and anaerobic spore formers were estimated at time intervals of 0, 5, 10, 15, and 20 days. TPC and LAB of pizza samples (atm1) reached 7.10 and 8.14 log CFU/g after 10 days of storage, respectively. Coliforms, psychrotrophs, and Y/M were significantly higher (p atm3>atm1 respectively, in descending order. MAP conditions under this study may extend shelf life of pizza to considerable amount of time.

The Importance of Endospore-Forming Bacteria Originating from Soil for Contamination of Industrial Food Processing

Specific endospore formers have become important contaminants in industrial food processing. The direct or indirect soil route of contamination or dispersal is the start of events or processes in the agrofood chain that eventually leads to important problems or concerns for food safety and/or quality. Three important food sectors are discussed in this paper. In the dairy sector,Bacillus cereus, the most important pathogen or spoilage organism in this sector, andClostridium tyrobutyricum, the most important spoiler in certain cheeses, both contaminate pasteurized milk through the faecal and/or (at least forB. cereus) the direct soil route. In the fruit juice industry,Alicyclobacillus acidoterrestris, present on raw fruits, has become a major quality-target organism. In the ready-to-eat food sector,B. cereusand other aerobic endospore formers are introduced via vegetables, fruits, or herbs and spices, while anaerobic spore formers like nonproteolyticClostridium botulinumandClostridium estertheticumpose safety and spoilage risks in chilled packaged foods, respectively.

Gene Analysis of Nosocomial Infection due to Clostridium difficile

Clostridium difficile is a spore-forming toxigenic obligate anaerobe that often causes C. difficile-associated diarrhea disease (CDAD) after the use of an antibacterial agent. Reportedly, C. difficile is resistant to heat, dryness, disinfectants, and antibacterial agents and often causes nosocomial infections. In the present study, we investigated clinical isolates to establish gene analysis (toxin and DNA types) required for epidemiological studies of nosocomial infections.

Caracterización molecular y resistencia antimicrobiana de aislamientos de Clostridium perfringens de diferentes orígenes en Costa Rica

Clostridium perfringens, a Gram positive, spore-forming anaerobe, is widely distributed in nature. Based upon their production of four major toxins alpha, beta, epsilon and iota, C. perfringens is classified into five toxinotypes (A-E). Some strains produce an enterotoxin (CPE), encoded by the cpe gene, which causes diarrhea in humans and some animals. C. perfringens strains that had been previously isolated and been kept at -80 degrees C were analyzed for the presence of toxin genes and for antimicrobial resistance: 20 from soils, 20 from animal, 20 from human origin and 21 from food non related to outbreaks. According to PCR results, all strains were classified as C. perfringens type A, since only alpha toxin gene was detected, while cpe was detected in two strains (2.5%) isolated from food, as it has been described in other world regions. Antibiotic resistance to at least one antibiotic was detected in 44% of the strains, 41% was resistant to clindamycin, 25% to chloramphenicol, 22% to penicillin and 20% to metronidazole. Soils strains showed the highest resistance percentages to almost all antibiotics. Multiresistance (to three or more antibiotic groups) was detected in the strains from soil (40%), human origin (30%), food (14%) and animal origin (5%). The high resistance rates found may be explained by the widespread use of antimicrobials as growth promoters in plants and animals; also these resistant strains may act as reservoir of resistance genes that may be transferred between bacteria in different environments.

Bacteriological quality of bottled natural mineral waters commercialized in Hungary

The purpose of the present study was to examine the bacteriological quality of bottled natural mineral waters sold in Hungary because, in recent years, there has been a tremendous increase in consumer demand for these products in the country. In total, 492 samples of domestic and imported brands of carbonated and non-carbonated mineral waters (246 samples each) were purchased from retail outlets, and were then screened for the presence of the following indicator and potentially pathogenic bacteria: spore-forming sulfite-reducing anaerobes (clostridia), total coliforms, Escherichia coli, Enterococcus spp., and Pseudomonas aeruginosa. Heterotrophic plate counts (HPC) were also determined by incubation at 37 °C for 24 h and at 22 °C for 72 h. The data generated were compared to the reference criteria set by Directive 2009/54/EC of the European Parliament and the Council of the European Union on the exploitation and marketing of natural mineral waters. The results showed that 5.3% and 10.2% of the carbonated and non-carbonated mineral water samples tested, respectively, were positive for at least one of the specific indicator or potentially pathogenic bacteria. Overall, a total of 38 sample units (7.7%) failed to comply with the standards set by Directive 2009/54/EC. None of the samples were judged non-compliant with current regulations on the basis of the presence of HPC bacteria at levels reaching or exceeding the acceptability limit (i.e., 100 CFU/ml at 22 °C or 20 CFU/ml at 37 °C) because the analyses were not carried out within 12 h after bottling, as required by Directive 2009/54/EC. The findings of this study highlight the need for a more stringent self-control by some producers of mineral water. In addition, a more systematic surveillance by the official authorities of food control is also necessary.

Thermoaciduric Clostridium pasteurianum spoilage of shelf-stable apple juice.

Clostridium pasteurianum BB, a saccharolytic and spore-forming obligate anaerobe, was isolated and identified from shelf-stable apple juice that was responsible for multiple large spoilage outbreaks. The growth and sporulation conditions of C. pasteurianum were atypical compared with those previously published. C. pasteurianum spores were heat resistant in apple juice at pH 3.80, with D-values at 80, 85, and 90°C being 34.4, 15.9, and 4.4 min, respectively, and a z-value of 11°C. The survival curves for thermal inactivation obeyed linear first-order kinetics. Apple juice with varying pH values was used to determine the effect of pH on germination capability of C. pasteurianum spores. The spores were found to be able to germinate at pH as low as 4.3 in pH-adjusted apple juice at low contamination levels. It was confirmed by PCR that C. pasteurianum isolated from spoiled apple juice did not contain the genes for botulinum toxins B and E, which were more commonly found in neurotoxigenic butyric clostridia. Control of finished-juice pH to below 4.0 in combination with mild heating was proposed to prevent potential spoilage of shelf-stable apple juice made with spore-contaminated apple juice concentrate.

Proteomic analysis of the insoluble subproteome of Clostridium difficile strain 630

Clostridium difficile, a Gram-positive spore-forming anaerobe, causes infections in humans ranging from mild diarrhoeal to potentially life-threatening pseudomembranous colitis. The availability of genomic information for a range of C. difficile strains affords researchers the opportunity to better understand not only the evolution of these organisms but also their basic physiology and biochemistry. We used proteomics to characterize the insoluble subproteome of C. difficile strain 630. Gel-based LC-MS analysis led to the identification of 2298 peptides; provalt analysis with a false discovery rate set at 1% concatenated this list to 560 unique peptides, resulting in 107 proteins being positively identified. These were functionally classified and physiochemically characterized and pathway reconstruction identified a variety of central anaerobic metabolic pathways, including glycolysis, mixed acid fermentation and short-chain fatty acid metabolism. Additionally, the metabolism of a variety of amino acids was apparent, including the reductive branch of the leucine fermentation pathway, from which we identified seven of the eight enzymes. Increasing proteomics data sets should - in conjunction with other 'omic' technologies - allow the construction of models for 'normal' metabolism in C. difficile 630. This would be a significant initial step towards a full systems understanding of this clinically important microorganism.

Quantitative real-time PCR assay for Clostridium septicum in poultry gangrenous dermatitis associated samples

Clostridium septicum is a spore-forming anaerobe frequently implicated in cases of gangrenous dermatitis (GD) and other spontaneously occurring myonecrotic infections of poultry. Although C. septicum is readily cultured from diseased tissues it can be difficult to enumerate due to its tendency to swarm over the surface of agar plates. In this study a quantitative real-time PCR assay was developed in order to more accurately measure the levels of C. septicum in healthy as well as GD associated poultry samples. The assay was specifically designed to target the C. septicum alpha toxin gene, csa, which is, to our knowledge, carried by all strains of C. septicum and has been shown to be essential for virulence. Genomic DNAs from a diverse collection of bacterial species, including closely related Clostridium chauvoei, Clostridium carnis, Clostridium tertium as well as several strains of Clostridium perfringens, all failed to produce a positive reaction. An approximate reproducible limit of detection in spiked extracts of at least 10 3 cfu/g of C. septicum was observed for a variety of different sample types. C. septicum levels in broiler chicken field samples estimated from the results of qPCR were statistically correlated to culture based enumerations obtained from those same tissues.

The Extension of the Shelf Life of Ready-to-Serve Pizza by a Combination of Modified Atmosphere Packaging and Refrigeration

This study evaluated the effect of modified atmosphere packaging on shelf-life extension of ready-to-serve pizza stored at 7±1°C using microbiological and sensory analysis. The gaseous atmospheres (atm) used were: atm 1: air (control); atm 2: 100% CO2, atm 3: 100% N2 and atm 4: 50%CO2/50%N2. Total plate count, yeasts/molds, coliforms, lactic acid bacteria, psychrotrophs and anaerobic spore formers were monitored. Sampling was carried out at predetermined time intervals namely 0, 15, 30, 45 and 60 days. Results of the present work show that the limit of sensory acceptability was only reached for the aerobically stored samples somewhat before days 15 of storage. However, a significant shelf life increase of 45 days (300% increase) was achieved under modified atmospheres for baked pizza samples. From the present study it can be concluded that amongst four atmospheres examined, atm 2 (100% CO2) was best, followed by atm 4 > atm 3 > atm 1 respectively, in descending order.