Survival of Salmonella spp. under varying temperature and soil conditions.

Soils can serve as suitable reservoirs for or barriers against microbial contamination of water resources and plant produce. The magnitude of water or food contamination risks through soil depends on several factors, including the survival potential of microorganisms in the soil. This study assessed and compared the survival/persistence of 14 Salmonella spp. strains in loam and sandy soils at 5, 10, 20, 25, 30, 35, 37 °C and under uncontrolled ambient temperature conditions in Campinas Sao Paulo. The ambient temperature ranged from 6 °C (minimum) to 36 °C (maximum). Bacterial population densities were determined by the conventional culture method (plate counts) and monitored for 216 days. Statistical differences among the test parameters were determined by Analysis of Variance, while relationships between temperature and soil type were evaluated using Pearson correlation analysis. Similarly, relationships between time and temperature for survival of the various strains were evaluated using Pearson correlation analysis. Results obtained indicate that temperature and soil type influence the survival of Salmonella spp. in soils. All 14 strains survived for up to 216 days in the organic-rich loam soil under at least three of the temperature conditions evaluated. However, comparatively lower survival rates were recorded in sandy soil, especially at lower temperature. The optimum temperature for survival varied among the strains, where some survived best at 5 °C and others between 30 and 37 °C. Under uncontrolled temperature conditions, the Salmonella strains survived better in loam than in sandy soils. Bacterial growth over post inoculation storage period was overall more impressive in loam soil. In general, the results indicate that temperature and soil type can interact to influence the survival of Salmonella spp. strains in soil. For the survival of some strains, there were significant correlations between soil type and temperature, while for some others, no significant relationship between soil and temperature was determined. A similar trend was observed for the correlation between time and temperature.

Survival behavior of six enterotoxigenic Escherichia coli strains in soil and biochar-amended soils.

Some Escherichia coli serotypes are important human pathogens causing diarrhea or in some cases, life threatening diseases. E. coli is also a typical indicator microorganism, routinely used for assessing the microbiological quality of water especially to indicate fecal contamination. The soil is a sink and route of transmission to water and food resources and it is thus important to understand the survival of enterotoxigenic E. coli strains in soil. This study monitored the survival of six E. coli strains in sandy and loam soil. Furthermore, since biochar is a commonly used soil conditioner, the study investigated the impact of biochar amendment (15%) on the survival of the E. coli strains in (biochar-amended) sandy and loam soils. Addition of biochar affected the physicochemical properties of both soils, altering potassium levels, calcium, magnesium, sodium as well as levels of other metal ions. It increased the organic matter of loam soil from 44 g/dm3 to 52 g/dm3, and increased the pH of both sandy and loam soils. Survival and persistence of the E. coli strains generally varied according to soil type, with strains generally surviving better (P ≤ 0.05) in loam soil compared to in sandy soil. In loam soil and biochar amended loam soils, E. coli strains remained culturable until the 150th day with counts ranging between 3.00 and 5.94 ± 0.04 log CFU/g. The effects of biochar on the physicochemical properties of soil and the response of the E. coli strains to biochar amendment was variable depending on soil type.

Microbiological quality of irrigation water for cultivation of fruits and vegetables: An overview of available guidelines, water testing strategies and some factors that influence compliance.

Contaminated irrigation water is among many potential vehicles of human pathogens to food plants, constituting significant public health risks especially for the fresh produce category. This review discusses some available guidelines or regulations for microbiological safety of irrigation water, and provides a summary of some common methods used for characterizing microbial contamination. The goal of such exploration is to understand some of the considerations that influence formulation of water testing guidelines, describe priority microbial parameters particularly with respect to food safety risks, and attempt to determine what methods are most suitable for their screening. Furthermore, the review discusses factors that influence the potential for microbiologically polluted irrigation water to pose substantial risks of pathogenic contamination to produce items. Some of these factors include type of water source exploited, irrigation methods, other agro ecosystem features/practices, as well as pathogen traits such as die-off rates. Additionally, the review examines factors such as food safety knowledge, other farmer attitudes or inclinations, level of social exposure and financial circumstances that influence adherence to water testing guidelines and other safe water application practices. A thorough understanding of relevant risk metrics for the application and management of irrigation water is necessary for the development of water testing criteria. To determine sampling and analytical approach for water testing, factors such as agricultural practices (which differ among farms and regionally), as well as environmental factors that modulate how water quality may affect the microbiological safety of produce should be considered. Research and technological advancements that can improve testing approach and the determination of target levels for hazard characterization or description for the many different pollution contexts as well as farmer adherence to testing requirements, are desirable.

Impact of temperature, soil type and compost amendment on the survival, growth and persistence of Listeria monocytogenes of non-environmental (food-source associated) origin in soil.

Listeria monocytogenes of varied sources including food-related sources may reach the soil. Associated food safety and environmental health risks of such contamination depend significantly on the capacity of L. monocytogenes to survive in the soil. This study assessed the survival of 13 L. monocytogenes strains isolated from food and food processing environments and a cocktail of three of the strains in two types of soils (loam and sandy) under controlled temperature conditions: 5, 10, 20, 25, 30℃ and 'uncontrolled' ambient temperature conditions in a tropical region. The impact of compost amendment on the survival of L. monocytogenes in the two different types of soils was also assessed. Soil type, temperature and compost amendment significantly (P <0.001) impacted the survival of L. monocytogenes in soil. Temperature variations affected the survival of L. monocytogenes in soil, where some strains such as strain 732, a L. monocytogenes 1/2a strain survived better at lower temperature (5°C), for which counts of up to 10.47 ± 0.005 log CFU/g were recovered in compost-amended sandy soil, 60 days post-inoculation. Some other strains such as strain 441, a L. monocytogenes 1/2a survived best at intermediate temperature (25 and 30 °C), while others such as 2739 (L. monocytogenes 1/2b) thrived at higher temperature (between 30 °C - 37 °C). There were significant correlations between the influence of temperature and soil type, where lower temperature conditions (5°C - 20°C) were generally more suitable for survival in sandy soil compared to higher temperature conditions. For some of the strains that thrived better in sandy soil at lower temperature, Pearson correlation analysis found significant correlations between temperature and soil type. Steady, controlled temperature generally favored the survival of the strains compared to uncontrolled ambient temperature conditions, except for the cocktail. The cocktail persisted until the last day of post-inoculation storage (60th day) in all test soils and under all incubation temperature conditions. Loam soil was more favorable for the survival of L. monocytogenes and compost amendment improved the survival of the strains, especially in compost-amended sandy soil. Listeria monocytogenes may exhibit variable survival capacity in soil, depending on conditions such as soil type, compost amendment and temperature.

Efficient removal of antibiotics from water resources is a public health priority: a critical assessment of the efficacy of some remediation strategies for antibiotics in water.

This review discusses the fundamental principles and mechanism of antibiotic removal from water of some commonly applied treatment techniques including chlorination, ozonation, UV-irradiation, Fenton processes, photocatalysis, electrochemical-oxidation, plasma, biochar, anaerobicdigestion, activated carbon and nanomaterials. Some experimental shortfalls identified by researchers such as certain characteristics of degradation agent applied and the strategies explored to override the identified limitations are briefly discussed. Depending on interactions of a range of factors including the type of antibiotic compound, operational parameters applied such as pH, temperature and treatment time, among other factors, all reviewed techniques can eliminate or reduce the levels of antibiotic compounds in water to varying extents. Some of the reviewed techniques such as anaerobic digestion generally require longer treatment times (up to 360, 193 and 170 days, according to some studies), while others such as photocatalysis achieved degradation within short contact time (within a minimum of 30, but up to 60, 240, 300 and 1880 minutes, in some cases). For some treatment techniques such as ozonation and Fenton, it is apparent that subjecting compounds to longer treatment times may improve elimination efficiency, whereas for some other techniques such as nanotechnology, application of longer treatment time generally meant comparatively minimal elimination efficiency. Based on the findings of experimental studies summarized, it is apparent that operational parameters such as pH and treatment time, while critical, do not exert sole or primary influence on the elimination percentage(s) achieved. Elimination efficiency achieved rather seems to be due more to the force of a combination of several factors.

Investigation into the bacterial diversity of sediment samples obtained from Berg River, Western Cape, South Africa.

This study used conventional culturing and 16S rRNA metagenomics analyses to assess the diversity of bacterial communities in sediment samples obtained from the Berg River, Western Cape, South Africa. Samples were collected from six points: a residential and recreational area, an industrial area, an informal residential settlement, a point next to a wastewater treatment plant (WWTP), a pumping station, and a residential and agricultural farming area along the river. High bacterial counts recorded on general selective and differential culture media signify substantial microbial contamination along the sampling sites. The most prevalent bacterial phyla detected (through metagenomics analyses) along the sampling sites were Proteobacteria (61%), Planctomycetes (9.5%), Firmicutes (7.8%), Bacteroidetes (5%), Acidobacteria (4.6%), and Actinobacteria (4.6%). Some members of the identified predominant bacterial phyla, genera, and classes are important public health bacteria that have been implicated in human diseases and outbreaks, while some others are metal or hydrocarbon tolerant, indicating possible significant environmental pollution. Notable human pathogenic genera such as Bacillus, Clostridium, Shigella, Legionella, Mycobacterium, and Pseudomonas were identified in varying percentages at five of the six sampling areas. Fecal contamination was particularly rife at all residential areas, with the informal housing area being the most notably polluted. Diverse functional pathways were predicted for identified bacteria, such as those associated with different chronic and infectious human diseases as well as those related to hydrocarbon and metal remediation. The point next to a WWTP contained vastly diverse groups of bacterial contaminants as well as the most abundant pathway identities and titles.

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 waste.

Manure-borne pathogens as an important source of water contamination: An update on the dynamics of pathogen survival/transport as well as practical risk mitigation strategies.

Enteropathogen contamination of water resources is a global concern. Several sources and routes of pathogen contamination of water resources have been identified including agriculture. Land spreading or disposal of manure/livestock wastes is a notable source of public health relevant microorganisms into water. Microorganisms can be transported from manure-amended soils into water, from where they can reach animals and humans and may cause infection. This review explores the public health relevance of manure-borne-pathogens, highlighting some of the diseases that manure associated pathogens cause. It also examines the dynamics of overland transport of pathogens into surface waters and percolation through soils into groundwater. Factors that influence the survival and transport of pathogens into respective water resources are discussed. The actual number of pathogens shed, pathogen release rate, requisite flow conditions, precipitation characteristics and pathogen inactivation potential are some general factors, examined in this review. Pathogen adaptation and survival in the soil environment is extensively discussed because soils significantly influence pathogen transfer into water. In addition to soil characteristics, environmental variables such as moisture, temperature and pH as well as soil biology are relevant aspects, considered herein. Manure and farm management practices such as manure source and type, storage and treatment, also influence the occurrence, survival and transport potential of pathogens. Optimized and recommended manure treatment techniques like composting, which has been demonstrated to satisfactorily inactivate enteric pathogens in manure are discussed. The need for proper composting by observing recommended manuring stipulations is emphasized and finally, practical strategies to protect water resources from pathogenic contamination are elucidated.

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.

How Functional Is Moringa oleifera? A Review of Its Nutritive, Medicinal, and Socioeconomic Potential.

Moringa oleifera is an important tropical food plant that seems to have great nutritional, therapeutic, industrial, agricultural, and socioeconomic value. Dietary consumption of its parts and preparations is encouraged by several organizations, health food enthusiasts, and other specialists as a strategy of personal health preservation and self-medication in the treatment of various diseases. Studies extoling its ability to mitigate various degenerative ailments now exist in both the scientific and the popular literature. At face value, and considering the volume of reports available, much of this enthusiasm seems to be indeed justified. However, it is imperative to distinguish rigorous scientific evidence from anecdote. To achieve this, relevant experimental and review articles were sought and read critically to identify recent patterns and trends on this subject matter. Studies on the medicinal and functional properties of M. oleifera are available from various parts of the world, especially developing regions. Attempts have been made to parse the contemporary scientific data available supporting the claims regarding the phytochemical, nutritive, medicinal, environmental, agricultural, and socioeconomic capabilities of this plant. Studies reviewed provide compelling, albeit preliminary experimental evidence of therapeutic potential of the plant. It is important that M. oleifera products and preparations be properly chemically characterized and standardized before being administered.

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.

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

Abstract 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.

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.

Co-metabolism of thiocyanate and free cyanide by Exiguobacterium acetylicum and Bacillus marisflavi under alkaline conditions.

The continuous discharge of cyanide-containing effluents to the environment has necessitated for the development of environmentally benign treatment processes that would result in complete detoxification of the cyanide-containing wastewaters, without producing additional environmental toxicants. Since biological detoxification of hazardous chemical compounds has been renowned for its robustness and environmental-friendliness, the ability of the Exiguobacterium acetylicum (GenBank accession number KT282229) and Bacillus marisflavi (GenBank accession number KR016603) to co-metabolise thiocyanate (SCN-) and free cyanide (CN-) under alkaline conditions was evaluated. E. acetylicum had an SCN- degradation efficiency of 99.9 % from an initial SCN- concentration of 150 mg SCN-/L, but the organism was unable to degrade CN-. Consequently, B. marisflavi had a CN- degradation efficiency of 99 % from an initial concentration of 200 mg CN-/L. Similarly, the organism was unable to degrade SCN-; hence, this resulted in the evaluation of co-metabolism of SCN- and CN- by the two microbial species. Optimisation of operational conditions was evaluated using response surface methodology (RSM). A numeric optimisation technique was used to evaluate the optimisation of the input variables i.e. pH, temperature, SCN- and CN- concentrations. The optimum conditions were found to be as follows: pH 9.0, temperature 34 °C, 140 mg SCN-/L and 205 mg CN-/L under which complete SCN- and CN- degradation would be achieved over a 168-h period. Using the optimised data, co-metabolism of SCN- and CN- by both E. acetylicum and B. marisflavi was evaluated, achieving a combined degradation efficiency of ≥99.9 %. The high degradative capacity of these organisms has resulted in their supplementation on an active continuous biological degradation system that is treating both SCN- and CN-.