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1.
FEMS Microbiol Rev ; 48(1)2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38216518

RESUMO

The potential for microbial activity to occur within the engineered barrier system (EBS) of a geological disposal facility (GDF) for radioactive waste is acknowledged by waste management organizations as it could affect many aspects of the safety functions of a GDF. Microorganisms within an EBS will be exposed to changing temperature, pH, radiation, salinity, saturation, and availability of nutrient and energy sources, which can limit microbial survival and activity. Some of the limiting conditions are incorporated into GDF designs for safety reasons, including the high pH of cementitious repositories, the limited pore space of bentonite-based repositories, or the high salinity of GDFs in evaporitic geologies. Other environmental conditions such as elevated radiation, temperature, and desiccation, arise as a result of the presence of high heat generating waste (HHGW). Here, we present a comprehensive review of how environmental conditions in the EBS may limit microbial activity, covering HHGW and lower heat generating waste (LHGW) in a range of geological environments. We present data from the literature on the currently recognized limits to life for each of the environmental conditions described above, and nutrient availability to establish the potential for life in these environments. Using examples where each variable has been modelled for a particular GDF, we outline the times and locations when that variable can be expected to limit microbial activity. Finally, we show how this information for multiple variables can be used to improve our understanding of the potential for microbial activity to occur within the EBS of a GDF and, more broadly, to understand microbial life in changing environments exposed to multiple extreme conditions.


Assuntos
Microbiologia Ambiental , Ambientes Extremos , Resíduos Radioativos , Resíduos Radioativos/análise
2.
Extremophiles ; 27(2): 17, 2023 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-37418077

RESUMO

Surface microbes are aerosolized into the atmosphere by wind and events such as dust storms, wildland fires, and volcano eruptions. Only microbial cells that survive the various atmospheric stressors during their transportation will deposit and colonize new environments. These stressors include desiccation, oxidative stress, solar radiation, osmotic shock, and freeze-thaw cycles. In this paper, we specifically studied the survival of representative microbial model strains isolated from the atmosphere over pristine volcanic landscapes to understand their potential to successfully disperse to novel terrestrial environments. In line with previous studies, we found that the most stringent selection factors were the freeze-thaw and osmotic shock cycles and that the strains affiliated with Proteobacteria and Ascomycota were the best to survive simulated atmospheric stresses. Specifically, isolates belonging to Paracoccus marinus, Janthinobacterium rivuli, and Sarocladium kiliense exhibited the highest levels of resistance to atmospheric stress. However, the number of strains tested in our study was limited and caution should be taken when generalizing these findings.


Assuntos
Congelamento , Islândia
3.
Food Res Int ; 165: 112536, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36869540

RESUMO

Sublethally injured state has been recognized as a survival strategy for microorganisms suffering from stressful environments. Injured cells fail to grow on selective media but can normally grow on nonselective media. Numerous microorganism species can form sublethal injury in various food matrices during processing and preservation with different techniques. Injury rate was commonly used to evaluate sublethal injury, but mathematical models for the quantification and interpretation of sublethally injured microbial cells still require further study. Injured cells can repair themselves and regain viability on selective media under favorable conditions when stress is removed. Conventional culture methods might underestimate microbial counts or present a false negative result due to the presence of injured cells. Although the structural and functional components may be affected, the injured cells pose a great threat to food safety. This work comprehensively reviewed the quantification, formation, detection, resuscitation and adaption of sublethally injured microbial cells. Food processing techniques, microbial species, strains and food matrix all significantly affect the formation of sublethally injured cells. Culture-based methods, molecular biological methods, fluorescent staining and infrared spectroscopy have been developed to detect the injured cells. Cell membrane is often repaired first during resuscitation of injured cells, meanwhile, temperature, pH, media and additives remarkably influence the resuscitation. The adaption of injured cells negatively affects the microbial inactivation during food processing.


Assuntos
Preservação Biológica , Ressuscitação , Membrana Celular , Ansiedade , Manipulação de Alimentos
4.
FEMS Microbiol Ecol ; 99(2)2023 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-36631299

RESUMO

Marine deep subsurface sediment is often a microbial environment under energy-limited conditions. However, microbial life has been found to persist and even thrive in deep subsurface environments. The Mariana forearc represents an ideal location for determining how microbial life can withstand extreme conditions including pH 10-12.5 and depleted nutrients. The International Ocean Discovery Program Expedition 366 to the Mariana Convergent Margin sampled three serpentinizing seamounts located along the Mariana forearc chain with elevated concentrations of methane, hydrogen, and sulfide. Across all three seamount summits, the most abundant transcripts were for cellular maintenance such as cell wall and membrane repair, and the most abundant metabolic pathways were the Entner-Doudoroff pathway and tricarboxylic acid cycle. At flank samples, sulfur cycling involving taurine assimilation dominated the metatranscriptomes. The in situ activity of these pathways was supported by the detection of their metabolic intermediates. All samples had transcripts from all three domains of Bacteria, Archaea, and Eukarya, dominated by Burkholderiales, Deinococcales, and Pseudomonales, as well as the fungal group Opisthokonta. All samples contained transcripts for aerobic methane oxidation (pmoABC) and denitrification (nirKS). The Mariana forearc microbial communities show activity not only consistent with basic survival mechanisms, but also coupled metabolic reactions.


Assuntos
Bactérias , Água do Mar , Água do Mar/microbiologia , Bactérias/genética , Bactérias/metabolismo , Archaea/genética , Archaea/metabolismo , Sedimentos Geológicos/microbiologia , Metano/metabolismo , Filogenia
5.
Res Microbiol ; 174(4): 104028, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36638934

RESUMO

Global industrialization and natural resources extraction have left cocktails of environmental pollutants. Thus, this work focuses on developing a defined actinobacteria consortium able to restore systems co-contaminated with pollutants occurring in Argentinian environments. In this context, five actinobacteria were tested in solid medium to evaluate antagonistic interactions and tolerance against lindane (LIN), Reactive Black B-V (RBV), phenanthrene (Ph) and Cr(VI). The strains showed absence of antagonism, and most of them tolerated the presence of individual pollutants and their mixtures, except Micromonospora sp. A10. Thus, a quadruple consortium constituted by Streptomyces sp. A5, M7, MC1, and Amycolatopsis tucumanensis DSM 45259T, was tested in liquid systems with individual contaminants. The best microbial growth was observed in the presence of RBV and the lowest on Cr(VI). Removals detected were 83.3%, 65.0% and 52.4% for Ph, RBV and LIN, respectively, with absence of Cr(VI) dissipation. Consequently, the consortium performance was tested against the organic mixture, and a microbial growth similar to the biotic control and a LIN removal increase (61.2%) were observed. Moreover, the four actinobacteria of the consortium survived the mixture bioremediation process. These results demonstrate the potential of the defined actinobacteria consortium as a tool to restore environments co-contaminated with organic pollutants.


Assuntos
Actinobacteria , Poluentes Ambientais , Poluentes do Solo , Actinobacteria/genética , Biodegradação Ambiental , Poluentes do Solo/análise , Hexaclorocicloexano , Cromo
6.
3 Biotech ; 12(11): 307, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36276476

RESUMO

Microorganisms are exposed to a wide variety of stress factors in their natural environments. Under that stressful conditions, they move into a viable but nonculturable (VBNC) state to survive and maintain the vitality. At VBNC state, microorganisms cannot be detected by traditional laboratory methods, but they can be revived under appropriate conditions. Therefore, VBNC organisms cause serious food safety and public health problems. To date, it has been determined that more than 100 microorganism species have entered the VBNC state through many chemical and physical factors. During the last four decades, dating from the initial detection of the VBNC condition, new approaches have been developed for the induction, detection, molecular mechanisms, and resuscitation of VBNC cells. This review evaluates the current data of recent years on the inducing conditions and detection methods of the VBNC state, including with microorganisms on the VBNC state, their virulence, pathogenicity, and molecular mechanisms.

7.
Compr Rev Food Sci Food Saf ; 21(5): 4327-4353, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36036722

RESUMO

Human milk and commercial dairy products play a vital role in humans, as they can provide almost all essential nutrients and immune-active components for the development of children. However, how to retain more native immune-active components of milk during processing remains a big question for the dairy industry. Nonthermal technologies for milk processing are gaining increasing interest in both academic and industrial fields, as it is known that thermal processing may negatively affect the quality of milk products. Thermosensitive components, such as lactoferrin, immunoglobulins (Igs), growth factors, and hormones, are highly important for the healthy development of newborns. In addition to product quality, thermal processing also causes environmental problems, such as high energy consumption and greenhouse gas (GHG) emissions. This review summarizes the recent advances of UV-C, ultrasonication (US), high-pressure processing (HPP), and other emerging technologies for milk processing from the perspective of immune-active components retention and microbial safety, focusing on human, bovine, goat, camel, sheep, and donkey milk. Also, the detailed application, including the instrumental design, technical parameters, and obtained results, are discussed. Finally, future prospects and current limitations of nonthermal techniques as applied in milk processing are discussed. This review thereby describes the current state-of-the-art in nonthermal milk processing techniques and will inspire the development of such techniques for in-practice applications in milk processing.


Assuntos
Gases de Efeito Estufa , Leite , Animais , Bovinos , Criança , Hormônios , Humanos , Recém-Nascido , Lactoferrina , Ovinos
8.
J Food Sci ; 87(6): 2310-2323, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35478321

RESUMO

The occurrence of disease outbreaks involving low-water-activity (aw ) foods has gained increased prominence due in part to the fact that reducing free water in these foods is normally a measure that controls the growth and multiplication of pathogenic microorganisms. Salmonella, one of the main bacteria involved in these outbreaks, represents a major public health problem worldwide and in Brazil, which highlights the importance of good manufacturing and handling practices for food quality. The virulence of this pathogen, associated with its high ability to persist in the environment, makes Salmonella one of the main challenges for the food industry. The objectives of this article are to present the general characteristics, virulence, thermoresistance, control, and relevance of Salmonella in foodborne diseases, and describe the so-called low-water-activity foods and the salmonellosis outbreaks involving them.


Assuntos
Doenças Transmitidas por Alimentos , Intoxicação Alimentar por Salmonella , Surtos de Doenças , Microbiologia de Alimentos , Doenças Transmitidas por Alimentos/epidemiologia , Humanos , Salmonella , Intoxicação Alimentar por Salmonella/epidemiologia , Intoxicação Alimentar por Salmonella/prevenção & controle , Água/análise
9.
J Appl Microbiol ; 132(5): 3973-3986, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35262283

RESUMO

AIMS: This study evaluated the behaviour of the Salmonella enterica serotypes in osmotically stressful BHI broth (0.940 ≤ aw  ≤ 0.960), assessing inoculum from two stages of the bacterial life cycle (exponential and stationary) and two temperatures (25°C and 35°C). METHODS AND RESULTS: Four S. enterica serotypes (Typhimurium, Enteritidis, Heidelberg and Minnesota) were grown in stressful BHI at 25°C. A mathematical model was proposed for describing the total microbial count as the sum of two subpopulations, inactivating and surviving-then-growing. When submitted to aw of 0.950 and 0.960, all strains showed a decreased count, followed by a period of unchanged count and then exponential growth (Phoenix Phenomenon). Strains inoculated at aw  = 0.940 and 0.945 showed inactivation kinetics only. Cells cultivated at 25°C and inoculated from the exponential phase were the most reactive to the osmotic stress, showing a higher initial population reduction and shorter adaptation period. The proposed model described the inactivation data and the Phoenix Phenomenon accurately. CONCLUSIONS: The results quantified the complex response of S. enterica to the osmotic environment in detail, depending on the inoculum characteristic and serotype evaluated. SIGNIFICANCE AND IMPACT OF STUDY: Quantifying these differences is truly relevant to food safety and improves risk analysis.


Assuntos
Salmonella enterica , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Pressão Osmótica , Sorogrupo , Água/análise
10.
Microbiol Res ; 258: 126997, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35247798

RESUMO

Acclimation and flexible response mechanisms are survival adaptations allowing prokaryotic cells to colonize diverse habitats and maintain viability in nature. Lack of water significantly impacts cellular response, which can be partially compensated for through community interactions and accessing survival means beyond the cell's boundaries. In the present study, higher numbers of cultivable Gram-positive Arthrobacter sp. and Gram-negative Pseudomonas stutzeri cells were found on surfaces when high population density was used after prolonged periods of desiccation and nutrient starvation. Total cell counts during desiccation periods decreased slower than culturable cell counts independently from initial population density. The presence of homogenate, prepared by filtering homogenized cultures through a 0.2 µm filter, extended culturability of Arthrobacter sp. cells, while intact heat-killed cells extended the culturability of Arthrobacter sp. and P. stutzeri. Our results suggest very slow cell membrane breakdown for desiccated bacterial cells at solid-air interfaces over extended time spans, which may serve as reservoirs of nutrients, and may potentially provide trace amounts of water for surviving cells. Higher initial population density and recycling of resources from "zombie"-like cells, may support growth in a similar fashion as access to cell lysates or the contents of heat-killed cells analogous to dead-phase cultures where some cells experience cryptic growth.


Assuntos
Arthrobacter , Dessecação , Nutrientes , Densidade Demográfica , Água
11.
Int J Food Sci Nutr ; 73(1): 49-59, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33957848

RESUMO

The consumption of probiotic foods is rather limited for many sectors of the population (vegans, lactose intolerant and celiacs). Therefore, it is necessary to offer functional alternatives for these sectors. Different red quinoa drinks were fermented with L. plantarum (QLPBB) and B. longum (QBLBB) at different times. Results showed that microbial concentration reached high levels (6-8 Log CFU/mL) after 6 h and probiotic viability was very high (6 Log CFU/mL) after gastrointestinal digestion (GD). However, QBLBB reached the best probiotic concentration at 24 h. From 6 h of fermentation, probiotic resistance to some antibiotics, especially B. longum, could have a great potential to restore the intestinal microbiota during and after treatment with certain antibiotics. QLPBB showed the highest levels of total polyphenols and antioxidant capacity (AOC) after GD. Therefore, these red quinoa drinks have potential as functional probiotic beverages for vegans, celiacs and allergic to milk protein and lactose-intolerant people.


Assuntos
Chenopodium quinoa , Probióticos , Digestão , Fermentação , Humanos , Lactose
12.
Microorganisms ; 9(9)2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34576857

RESUMO

Riojano chorizo is a dry cured sausage manufactured with traditional technologies without adding starter cultures at low temperatures. Its characteristics differ from other types of chorizo since sugars and nitrites are no added and processing temperatures are low- This work evaluates the behaviour of Listeria monocytogenes during the processing of inoculated Riojano chorizo as well as the natural microflora that can play a technological role or be of interest as indicators. The sausage mixture was inoculated with a cocktail of three selected strains of L. monocytogenes (CECT 932, CECT 934 and CECT 4032) (4 log10 CFU/g) and after processed following the traditional production method. Samples were taken before inoculation, after inoculation, after stuffing (day 0) and on days 6, 13, 21 and 28 of processing. L. monocytogenes, mesophiles, Micrococcaceae, lactic acid bacteria, Enterobacteriaceae, S. aureus, sulfite-reducing clostridia and molds and yeast counts were evaluated. Furthermore, pH, water activity and humidity were determined. No growth of L mocytogenes was observed during the first 6 days, when the temperature of processing was 4 °C. The low temperature in the initial stages was a relevant hurdle to control L. monocytoegenes growth. A significant decrease (p ≤ 0.05) in L. monocytogenes counts was observed on day 13 compared to the initial counts. During drying (days 6 to 21) a reduction in this pathogen of 1.28 log CFU/g was observed. The low water activity below 0.92 on day 13 and 0.86 on day 21 seems to be critical for the reduction of L. monocytogenes.

13.
Microorganisms ; 9(7)2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34202256

RESUMO

Sliced ready-to-eat meat products packaged under modified atmospheres are often marketed since they cover consumer demands. The slicing process could be a potential risk for consumers since contamination with Listeria monocytogenes could occur during this stage. The current study evaluated the behavior of L. monocytogenes and other microorganisms in commercial sliced Riojano chorizo. This meat product was sliced and inoculated with L. monocytogenes (3.5 log CFU/g) before packaging under different atmospheres (air, vacuum, 100% N2, 20% CO2/80% N2 and 40% CO2/60% N2) and stored at 4 °C for up to 60 days. Samples were taken on days 0, 7, 21, 28 and 60 of storage. L. monocytogenes, mesophiles, Enterobacteriaceae, lactic acid bacteria, Micrococcaceae, molds and yeast counts were evaluated. Additionally, water activity, humidity and pH were determined. L. monocytogenes counts decreased in inoculated sliced chorizo during storage. Packaging conditions and day of storage influenced microbial counts. After 60 days, a significant reduction (p ≤ 0.05) in the initial Listeria contamination levels (3.5. log CFU/g) between 1.1 and 1.46 logarithmic units was achieved in the sausages packaged in modified atmosphere. The highest reductions were observed in slices packaged in 40% CO2/60% N2 after 60 days of storage at 4 °C.

14.
Vet World ; 14(6): 1695-1710, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34316221

RESUMO

BACKGROUND AND AIM: Water magnetization contributes to increased molecular ionization and fluidity, which improves biological activities. This study tests the influence of magnetic water on the viability of the Newcastle vaccine and the survival of Escherichia coli and SalmonellaTyphimurium, as well as the influence of magnetic water in face of water impurities' challenges on performance, immunity, and tissue architecture in broiler chickens. MATERIALS AND METHODS: An in vitro 96-micro-well plate minimal inhibitory concentration was utilized to test the influence of water, saline, and magnetic water on Newcastle vaccine viability and E. coli O157:H7 and S. Typhimurium survival. The 245 experimental 1-day-old female Ross® 308 broilers used in this study were divided into seven groups of 35 birds each. Broilers were provided with magnetic drinking water (13,200 gausses) for 6 h daily from the 5th day and were challenged on days 14, 21, 28, and 35 using sodium chloride (700 mg/L), calcium sulfate (80 mg/L), lead acetate (500 mg/L), yeast extract 5% (5 mg/L), diazinon (2.5 mL/L), and E. coli O157:H7 (1.6 × 109 CFU/mL). A total of 2040 samples (96 diluent-Newcastle virus vaccine mixes, 96 microbial-magnetic water mixes, 231 sera, 231 intestinal swabs, and 1386 organ samples) were collected. RESULTS: An in vitro trial revealed highly significant (p<0.01) declines of 94.13%, 84.53%, and 10.31% in the Newcastle vaccine titer in water, saline, and magnetic water, respectively, and 54.91% and 39.89% in E. coli O157:H7 and S. Typhimurium survival, respectively, after 4 h. In all challenged groups, broilers exhibited highly significant (p<0.01) increases in performance, carcass/organs weight, immunoglobulin G, immunoglobulin M, and Lactobacillus counts; significant improvement in tissue architecture and biochemical parameters; and highly significant (p<0.01) reductions in cortisol, superoxide dismutase, and total bacterial and Enterobacteriaceae counts. CONCLUSION: Magnetic water could maintain vaccine viability and vaccination efficiency, reduce microbial survival, and minimize the negative influence of all induced challenges.

15.
J Environ Manage ; 294: 113018, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34144322

RESUMO

Manure inputs into soil strongly affect soil microbial communities leading to shifts in microbial diversity and activity. It is still not clear whether these effects are caused mainly by the survival of microbes introduced with manure or by activation of the soil-borne microbiome. Here, we investigated how the soil microbiome was changed after the introduction of fresh farmyard cattle manure, and which microorganisms originating from manure survived in soil. Manure addition led to a strong increase in soil microbial biomass, gene copies abundances, respiration activity, and diversity. High-throughput sequencing analysis showed that higher microbial diversity in manured soil was caused mainly by activation of 113 soil-borne microbial genera which were mostly minor taxa in not-fertilized soil. Two weeks after manure input, 78% of the manure-associated genera were not detected anymore. Only 15 of 237 prokaryotic genera that originated from manure survived for 144 days in soil, and only 8 of them (primarily representatives of Clostridia class) were found in manured soil after winter. Thus, an increase in microbial biomass and diversity after manure input is caused mainly by activation of soil-borne microbial communities, while most exogenous microbes from manure do not survive in soil conditions after few months.


Assuntos
Esterco , Microbiota , Animais , Bovinos , Fertilizantes/análise , Microbiota/genética , Solo , Microbiologia do Solo
16.
Microb Physiol ; 31(2): 88-98, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34107493

RESUMO

Amyloids have proven to be a widespread phenomenon rather than an exception. Many proteins presenting the hallmarks of this characteristic beta sheet-rich folding have been described to date. Particularly common are functional amyloids that play an important role in the promotion of survival and pathogenicity in prokaryotes. Here, we describe important developments in amyloid protein research that relate to microbe-microbe and microbe-host interactions in the plant microbiome. Starting with biofilms, which are a broad strategy for bacterial persistence that is extremely important for plant colonization. Microbes rely on amyloid-based mechanisms to adhere and create a protective coating that shelters them from external stresses and promotes cooperation. Another strategy generally carried out by amyloids is the formation of hydrophobic surface layers. Known as hydrophobins, these proteins coat the aerial hyphae and spores of plant pathogenic fungi, as well as certain bacterial biofilms. They contribute to plant virulence through promoting dissemination and infectivity. Furthermore, antimicrobial activity is an interesting outcome of the amyloid structure that has potential application in medicine and agriculture. There are many known antimicrobial amyloids released by animals and plants; however, those produced by bacteria or fungi remain still largely unknown. Finally, we discuss amyloid proteins with a more indirect mode of action in their host interactions. These include virulence-promoting harpins, signaling transduction that functions through amyloid templating, and root nodule bacteria proteins that promote plant-microbe symbiosis. In summary, amyloids are an interesting paradigm for their many functional mechanisms linked to bacterial survival in plant-associated microbial communities.


Assuntos
Proteínas Amiloidogênicas , Microbiota , Amiloide , Animais , Bactérias , Biofilmes
17.
Math Biosci ; 338: 108615, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33857526

RESUMO

Understanding how environmental factors affect microbial survival is an important open problem in microbial ecology. Patterns of microbial community structure have been characterized across a wide range of different environmental settings, but the mechanisms generating these patterns remain poorly understood. Here, we use mathematical modelling to investigate fundamental connections between chemical power supply to a system and patterns of microbial survival. We reveal a complex set of interdependences between power supply and distributions of survival probability across microbial habitats, in a case without interspecific resource competition. We also find that different properties determining power supply, such as substrate fluxes and Gibbs energies of reactions, affect microbial survival in fundamentally different ways. Moreover, we show how simple connections between power supply and growth can give rise to complex patterns of microbial survival across physicochemical gradients, such as pH gradients. Our findings show the importance of taking energy fluxes into account in order to reveal fundamental connections between microbial survival and environmental conditions, and to obtain a better understanding of microbial population dynamics in natural environments.


Assuntos
Viabilidade Microbiana , Microbiota , Modelos Biológicos , Fontes de Energia Elétrica , Microbiota/fisiologia , Dinâmica Populacional
18.
Compr Rev Food Sci Food Saf ; 19(1): 149-183, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-33319518

RESUMO

The viable but nonculturable (VBNC) state has been recognized as a strategy for bacteria to cope with stressful environments; in this state, bacteria fail to grow on routine culture medium but are actually alive and can resuscitate into a culturable state under favorable conditions. The VBNC state may pose a great threat to food safety and public health. To date, more than 100 VBNC microorganism species have been proven to exist in fields of food safety, environmental application, and agricultural diseases. Most harsh conditions can induce these microorganisms into the VBNC state, including food processing and preservation methods, adverse environmental conditions, and plant-disease controlling means. The characteristics of VBNC state cells differ from those of normally growing cells and dead cells, based on which of the various detection methods are developed, and they are of great significance for potential risk assessment. To provide molecular level insights into this state, many studies on induction and resuscitation mechanisms have emerged over the past three decades, including research on omics, specific genes, or proteins involved in VBNC state formation and the roles of promoters in resuscitation from the VBNC state. In this review, microorganism species, induction and resuscitation factors, detection methods, and formation and resuscitation mechanisms of the VBNC state are comprehensively and systematically summarized.


Assuntos
Fenômenos Fisiológicos Bacterianos , Microbiologia de Alimentos/métodos , Viabilidade Microbiana , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Microbiologia Ambiental , Manipulação de Alimentos/métodos , Inocuidade dos Alimentos , Fungos/crescimento & desenvolvimento , Fungos/fisiologia
19.
J Food Sci ; 85(10): 3478-3486, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32901935

RESUMO

The finding of economical and practical applications for milk whey is still a challenge for dairy industries. This paper presents information about the development of a probiotic-prebiotic beverage based on Lactobacillus rhamnosus GG (LGG) and Costa Rican guava (CRG) fruit pulp with industrial potential. First, a supplemented whey media was developed for LGG growth, and the whey-supplemented media was used for fermentation in bioreactors. LGG reached a maximum growth rate of 0.32 hr-1 after 48 hr of fermentation. The whey-grown probiotics were then mixed with CRG pulp to produce the probiotic-prebiotic beverage. The survival kinetics of LGG in the formulated drink was not affected by the addition of CRG pulp (P > 0.05), and the shelf-life of the inoculated beverage surpassed 40 days with a minimum population of 106 colony forming units (CFU)/mL. Properties as pH, fructose, glucose, sucrose, and proanthocyanidins (PACs) content exhibited a significant difference after storage time (P < 0.05). Finally, three different formulas of the beverage with different whey content were compared through sensory evaluation. The prototype with 50% whey content was one of the most valuable beverage formulas according to the organoleptic parameters, which remarks about the possibility of developing a probiotic whey-based beverage containing CRG pulp. Furthermore, this is the first report about CRG beverages as a probiotic vector. PRACTICAL APPLICATION: This research focuses on the evaluation of the properties of a probiotic beverage, with a promissory industrial application using whey, as a dairy industry byproduct, combined with the pulp of the highly nutritious and subutilized Costa Rican guava (CRG) fruit.


Assuntos
Bebidas/análise , Lacticaseibacillus rhamnosus/crescimento & desenvolvimento , Prebióticos/análise , Probióticos/química , Psidium/química , Animais , Bebidas/microbiologia , Bovinos , Fermentação , Armazenamento de Alimentos , Frutas/química , Cinética , Lacticaseibacillus rhamnosus/química , Leite/química , Leite/microbiologia , Prebióticos/microbiologia , Resíduos/análise , Proteínas do Soro do Leite/análise , Proteínas do Soro do Leite/metabolismo
20.
Foods ; 9(6)2020 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-32570771

RESUMO

A new ultrasonic reactor was used to rapidly inactivate Escherichia coli and Staphylococcus aureus in apple juice. It was found that high pulp content made ultrasound less lethal to S. aureus, while it had no significant effect on E. coli. When the pulp free apple juice was ultrasonically processed, the 5-log reduction time was 35 s for E. coli at 60 °C and 30 s for S. aureus at 62 °C. Ultrasound treatment had no significant effect on antioxidant activity determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, but it significantly increased the total phenolic content. The treatment also resulted in more stable juice with higher uniformity. During 28 d of storage at 4 °C, the total plate count in apple juice ultrasonically treated at 60 °C for 35 s remained around 1.00 log CFU/mL, whereas it was nearly zero for a stronger ultrasound treatment at 62 °C for 30 s. These values were much lower than those in the untreated one, which increased from 3.65 log CFU/mL to 8.36 log CFU/mL during the storage. At the end of the storage, the control and thermally treated apple juice lost almost 70% of antioxidant activity, whereas the ultrasonically treated juice only lost 20-40%.

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