Sources and contamination routes of microbial pathogens to fresh produce during field cultivation: A review

Foodborne illness resulting from the consumption of contaminated fresh produce is a common phenomenon and has severe effects on human health together with severe economic and social impacts. The implications of foodborne diseases associated with fresh produce have urged research into the numerous ways and mechanisms through which pathogens may gain access to produce, thereby compromising microbiological safety. This review provides a background on the various sources and pathways through which pathogenic bacteria contaminate fresh produce; the survival and proliferation of pathogens on fresh produce while growing and potential methods to reduce microbial contamination before harvest. Some of the established bacterial contamination sources include contaminated manure, irrigation water, soil, livestock/ wildlife, and numerous factors influence the incidence, fate, transport, survival and proliferation of pathogens in the wide variety of sources where they are found. Once pathogenic bacteria have been introduced into the growing environment, they can colonize and persist on fresh produce using a variety of mechanisms. Overall, microbiological hazards are significant; therefore, ways to reduce sources of contamination and a deeper understanding of pathogen survival and growth on fresh produce in the field are required to reduce risk to human health and the associated economic consequences

Bioremediation of polycyclic aromatic hydrocarbons (PAHs) in water using indigenous microbes of Diep- and Plankenburg Rivers, Western Cape, South Africa

Thesis (MTech (Environmental Management))--Cape Peninsula University of Technology, 2015.This study was conducted to investigate the occurrence of PAH degrading microorganisms in two river systems in the Western Cape, South Africa, and their ability to degrade two PAH compounds (acenaphthene and fluorene). A total of 19 bacterial isolates were obtained from the Diep- and Plankenburg Rivers. These microorganisms were first identified phenotypically on various selective and general media (such as nutrient agar, Eosine Methylene Blue and Mannitol Salts Agar), followed by staining and biochemical testing, followed by molecular identification using 16S rRNA and PCR. The isolates were then tested for acenaphthene and fluorene degradation first at flask scale and then in a Stirred Tank Bioreactor at varying temperatures (25ºC, 30ºC, 35ºC, 37ºC, 38ºC, 40ºC and 45ºC). All experiments were run without the addition of supplements, bulking agents, biosurfactants or any other form of biostimulants. Four of the 19 isolated microorganisms were identified as acenaphthene and fluorene degrading isolates. Three of the four microorganisms identified as PAH degrading isolates were Gram negative isolates. Results showed that Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila efficiently degraded fluorene (99.90%, 97.90%, 98.40% and 99.50%) and acenaphthene (98.60%, 95.70%, 90.20% and 99.90%) at 37ºC, 37ºC, 30ºC and 35ºC, respectively. The degradation of fluorene was found to be more efficient and rapid compared to that of acenaphthene and degradation at Stirred Tank Bioreactor scale was more efficient for all treatments. Throughout the biodegradation experiments, there was an exponential increase in microbial plate counts ranging from 5 x 104 to 9 x 108 CFU/ml. The increase in plate count was observed to correlate with the efficient degradation temperature profiles and percentages. The PAH degrading microorganisms isolated during this study significantly reduced the concentrations of acenaphthene and fluorene and can be used on a larger, commercial scale to bioremediate PAH contaminated river systems. Other factors that influence the optimal expression of biodegradative potential of microorganisms other than temperature and substrate (nutrient) availability, such as pH, moisture and salinity will be investigated in future studies, as well as the factors contributing to the higher fluorene degradation compared to acenaphthene. Furthermore, the structure and toxicity of the by-products and intermediates produced during microbial metabolism of acenaphthene and fluorene should be investigated in further studies

Understanding the public health burden of unconventional produce-associated enteropathogens

Emerging pathogens, which although have been periodically detected in produce items, are comparatively rarely implicated in large outbreaks. Many of these pathogens are inhabitants of the natural environment and may be major potential sources of contamination for fruits and vegetables. This overview examines the growing epidemiological relevance of three of such emerging pathogens; Arcobacter spp., Helicobacter pylori and Cronobacter sakazakii and the recent status of the scientific literature on their potential for transmission to humans via the consumption of fruits and vegetables. There appears to be a potentially important, yet overlooked exposure risk for humans via produce consumption. Certain crucial research gaps such as the need to optimize detection approaches for the swift and accurate isolation of these agents from produce items has been identified. To establish comprehensive microbiological criteria for produce safety, it is important to characterize all associated potential human pathogens323744CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES#305804/2017-0; #148279/2017-1Sem informaçã

Investigation into the bacterial pollution levels at various sites along the Diep and Plankenburg river systems, 3 Western Cape, South Africa.

This study sought to investigate and compare bacterial contamination levels at six different sites along the Diep and Plankenburg river systems in the Western Cape, South Africa. Surface water and sediment samples were collected monthly from the six selected sampling sites along both river courses between January 2014 and December 2014 and were evaluated for bacterial contaminants. Microbial isolation, characterisation and identification were done using conventional techniques (serial dilution, Gram staining, and biochemical testing) and molecular identification techniques (polymerase chain reaction and DNA sequencing). A total of 19 bacterial isolates belonging to the genera Raoultella, Bacillus, Pseudomonas, Klebsiella, Escherichia, Enterobacter, Exiguobacterium, Acinetobacter, Serratia, Aeromonas, Staphylococcus and Citrobacter were isolated from the surface water and sediment samples at the end of the survey. Higher microbial load was obtained from sediment samples compared to surface water samples. Seasonal variation was also observed in terms of microbial counts. Higher microbial counts were obtained during summer sampling time compared to winter sampling time. The most contaminated site was located on Plankenburg River with average bacterial counts ranging between 3.1 × 10(5)-6.9 × 10(8) CFU/ml and 3.9 × 10(6)-2.88 × 10(9) CFU/ml from surface water and sediment, respectively, recorded at this site during winter and summer. Although lower microbial counts were recorded along the Diep River course, most of the bacterial counts recorded along both rivers exceeded the acceptable maximum limits for river water

Bioremediation of polycyclic aromatic hydrocarbon (PAH) compounds: (acenaphthene and fluorene) in water using indigenous bacterial species isolated from the Diep and Plankenburg rivers, Western Cape, South Africa

This study was conducted to investigate the occurrence of PAH degrading microorganisms in two river systems in the Western Cape, South Africa and their ability to degrade two PAH compounds: acenaphthene and fluorene. A total of 19 bacterial isolates were obtained from the Diep and Plankenburg rivers among which four were identified as acenaphthene and fluorene degrading isolates. In simulated batch scale experiments, the optimum temperature for efficient degradation of both compounds was determined in a shaking incubator after 14 days, testing at 25 °C, 30 °C, 35 °C, 37 °C, 38 °C, 40 °C and 45 °C followed by experiments in a Stirred Tank Bioreactor using optimum temperature profiles from the batch experiment results. All experiments were run without the addition of supplements, bulking agents, biosurfactants or any other form of biostimulants. Results showed that Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila efficiently degraded both compounds at 37 °C, 37 °C, 30 °C and 35 °C respectively. The degradation of fluorene was more efficient and rapid compared to that of acenaphthene and degradation at Stirred Tank Bioreactor scale was more efficient for all treatments. Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila degraded a mean total of 98.60%, 95.70%, 90.20% and 99.90% acenaphthene, respectively and 99.90%, 97.90%, 98.40% and 99.50% fluorene, respectively. The PAH degrading microorganisms isolated during this study significantly reduced the concentrations of acenaphthene and fluorene and may be used on a larger, commercial scale to bioremediate PAH contaminated river systems

Polycyclic aromatic hydrocarbons: A critical review of environmental occurrence and bioremediation

The degree of polycyclic aromatic hydrocarbon contamination of environmental matrices has increased over the last several years due to increase in industrial activities. Interest has surrounded the occurrence and distribution of polycyclic aromatic hydrocarbons for many decades because they pose a serious threat to the health of humans and ecosystems. The importance of the need for sustainable abatement strategies to alleviate contamination therefore cannot be overemphasised, as daily human activities continue to create pollution from polycyclic aromatic hydrocarbons and impact the natural environment. Globally, attempts have been made to design treatment schemes for the remediation and restoration of contaminated sites. Several techniques and technologies have been proposed and tested over time, the majority of which have significant limitations. This has necessitated research into environmentally friendly and cost-effective clean-up techniques. Bioremediation is an appealing option that has been extensively researched and adopted as it has been proven to be relatively cost-effective, environmentally friendly and is publicly accepted. In this review, the physicochemical properties of some priority polycyclic aromatic hydrocarbons, as well as the pathways and mechanisms through which they enter the soil, river systems, drinking water, groundwater and food are succinctly examined. Their effects on human health, other living organisms, the aquatic ecosystem, as well as soil microbiota are also elucidated. The persistence and bioavailability of polycyclic aromatic hydrocarbons are discussed as well, as they are important factors that influence the rate, efficiency and overall success of remediation. Bioremediation (aerobic and anaerobic), use of biosurfactants and bioreactors, as well as the roles of biofilms in the biological treatment of polycyclic aromatic hydrocarbons are also explored

Understanding spoilage microbial community and spoilage mechanisms in foods of animal origin

The increasing global population has resulted in increased demand for food. Goods quality and safe food is required for healthy living. However, food spoilage has resulted in food insecurity in different regions of the world. Spoilage of food occurs when the quality of food deteriorates from its original organoleptic properties observed at the time of processing. Food spoilage results in huge economic losses to both producers (farmers) and consumers. Factors such as storage temperature, pH, water availability, presence of spoilage microorganisms including bacteria and fungi, initial microbial load (total viable count—TVC), and processing influence the rate of food spoilage. This article reviews the spoilage microbiota and spoilage mechanisms in meat and dairy products and seafood. Understanding food spoilage mechanisms will assist in the development of robust technologies for the prevention of food spoilage and waste192311331The authors acknowledge the financial support for editing of the manuscript provided by National Scientific Program “Healthy Foods for a Strong Bio‐Economy and Quality of Life” approved by DCM No. 577/17.08.2018, funded by Bulgarian Ministry of Education and Scienc

Hazards of a ‘healthy’ trend? An appraisal of the risks of raw milk consumption and the potential of novel treatment technologies to serve as alternatives to pasteurization

Milk is a nutritious and healthy dietary component of many adults and infants, all over the world. For numerous reasons, the consumption of raw, unpasteurized milk is a growing trend. This practice may, however, be risky as raw milk consumption has potentially severe health consequences. Scope and approach In the midst of the fierce debate and controversy, it is important to find support in rigorous scientific evidence. In this review, the contemporary epidemiological significance of raw milk, as well as the scientific basis and justification for milk pasteurization, are presented. The hazards associated with raw milk consumption, the primary sources and routes of microbial contaminants into milk, as well as factors that may predispose milk to microbial contamination, are explored. Relevant livestock commensal microbiota and diseases, environmental sources and pathways, as well as post-pasteurization contamination are considered. Some of the motivating factors driving raw milk consumption and the purported benefits of drinking unpasteurized milk are examined. Furthermore, the main scientifically verified differences between pasteurized and unpasteurized milk are discussed, and attempts are made to refute some of the biased claims regarding the human health benefits of raw milk. Given that many raw milk enthusiasts are skeptical of pasteurization, we explore the potential of some novel treatment techniques that could serve as alternatives to pasteurization. Key findings and conclusions Scientific evidence shows that pasteurization is so far, the primary, incontrovertible safeguard for milk and it only slightly alters the nutritive and organoleptic profile of milk. There are a number of novel technologies, which seem to be milder and if properly optimized in the near future may serve as suitable alternatives to pasteurization. It is anticipated that these technologies or a reasonable combination of key processes, will enable the production of milk and milk products that are microbiologically safe, yet publicly accepted82148166CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES#305804/2017-0; #148279/2017-1#33003017027P

Impacts of vending practices on the microbiological quality of bread in the Ojoo Area of Ibadan, Oyo-State, Nigeria

Background: Bacterial counts in ready-to-eat foods are a key factor in assessing the microbiological quality and safety of food. Periodic assessment of the microbiological quality of food is necessary to develop a robust database and help to ensure food safety. Methods: The bacterial contamination of a total of 336 bread samples collected from two bakeries and 10 vendors in Ojoo Area of Ibadan, Oyo-State, Nigeria (December 2014 -June 2015) was evaluated. The microbiological quality of the bread loaves was investigated using standard microbiological methods (morphological, phenotypic and molecular characterization). Results: The results showed that the number of contaminated samples among the vended bread samples was higher than the bakery bread samples and can be summarized as Bacillus megaterium (4.30%), Staphylococcus arlettae (0.005%), Staphylococcus saprophyticus (2.78%), Citrobacter freundii (2.40%), Bacillus flexus (1.64%), Bacillus species (49.59%), Pseudomonas aeruginosa (4.12%), Pseudomonas fluorescens (0.92%), Pseudomonas species (0.045%), Escherichia coli (30.44%) Klebsiella sp. (0.040%) and Aeromonas hydrophila (3.72%). Conclusion: The findings demonstrate that the bread samples which become contaminated after transport and handling can be considered a potential hazard to human health in the area. More stringent adherence to food safety regulations should be encouraged and enforced by the appropriate authorities. The findings of this study may be adopted to improve the hygienic conditions of bread distribution chain in the area as well as in other regions of the World.151313