Bacteria Causing Gastrointestinal Infections
K. Balamurugan, U. Prithika in Pocket Guide to Bacterial Infections, 2019
The genus Yersinia consists of 11 species out of which 3 are important causes of human infections, namely Y. enterocolitica, Y. pseudotuberculosis, and Y. pestis. Yersiniosis, a foodborne GI infection is primarily caused by Y. enterocolitica and less commonly by Y. pseudotuberculosis. Y. pestis is the causative organism for pulmonic and bubonic plague. Y. enterocolitica are gram-negative coccobacilli with peritrichous flagella and are facultative anaerobes belonging to Enterobacteriaceae family (Bottone 1997). They are psychrophilic and often require a cold enrichment step for isolation. Infections are common during winter and are frequent in temperate countries. They have an extensive animal reservoir, and the most frequent mode of infection is by eating undercooked pork and drinking raw milk and contaminated water. Yersiniosis is the third-most common zoonosis in the European Union after Campylobacter and nontyphoidal salmonellosis (Hoffmann et al. 2012). Lithuania and France have the highest rate at 12.9 and 9.8 cases per 100,000 population, respectively. Children younger than 5 years of age are commonly affected. Diabetes, iron overload, blood transfusion, malnutrition, alcoholism (Rabson et al. 1975; Bouza et al. 1980) are some of the predisposing factors for Yersiniosis. Iron is required for the virulence of these organisms.
Inorganic Chemical Pollutants
William J. Rea, Kalpana D. Patel in Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
In the absence of genome sequences for all Hg-methylating organisms, the generality of the present findings cannot yet be ascertained. However, their interpretation is in agreement with all currently available sequence information for methylating bacteria and archaea. The presence of the hgcAB cluster in the genomes of several sequenced, but so far untested, microorganisms leads them to hypothesize that these organisms are also capable of methylating mercury. The gene cluster appears to be quite sporadically distributed across two phyla of bacteria (Proteobacteria and Firmicutes) and one phylum of archaea (Euryarchaeota). Organisms possessing the two-gene cluster include 24 strains of Deltaproteobacteria, 16 Clostridia, 1 Negativicutes, and 11 Methanomicrobia. Interestingly, they also found these genes in a psychrophile,583 in a thermophile,584 and in a human commensal methanogen.585 The sporadic distribution of these genes and the lack of an obvious selective advantage related to mercury toxicity raise important questions regarding their physiological roles. Identification of these genes is a critical step linking specific microorganisms and environmental factors that influence microbial Hg methylation in aquatic ecosystems.
Biology of microbes
Philip A. Geis in Cosmetic Microbiology, 2006
Temperature affects microorganisms because they have no way to control their own temperatures and because enzymatic reactions required for growth are affected by temperature in the same way any other chemical reaction is affected: the rate of reaction roughly doubles for every 10°C rise in temperature. At low temperatures, the enzymes operate more slowly and thus growth is also slower. Up to a certain temperature, growth increases until the point is reached where high temperatures are lethal because they damage cells by denaturing proteinaceous enzymes, destroying transport proteins, and destroying lipid membranes. The key or cardinal temperatures to consider for each species of microbe are the minimum, optimum, and maximum. Temperature ranges for the major groups of organisms of concern are shown in Table 2.4. Microorganisms can be placed into four categories based on their temperature ranges. Psychrophiles grow between 0 and 20°C and are found throughout Arctic and Antarctic regions as well as in man-made refrigerated environments. In alpine snowfields, the psychrophilic alga, Chlamydomonas nivalis, produces pink snow. Psychrophilic bacteria include members of the genera Pseudomonas, Flavobacterium, Achromobacter, and Alcaligenes. Facultative psychrophiles grow optimally at 20 to 30°C and can spoil refrigerated foods. Few, if any, of these organisms present problems for consumer products because they only act as spoilage organisms and consumer products are rarely kept at low temperatures. Psychrophiles and psychrotrophs are not pathogens, although some produce toxins that, if ingested, may cause problems.
The oceans are changing: impact of ocean warming and acidification on biofouling communities
Published in Biofouling, 2019
Sergey Dobretsov, Ricardo Coutinho, Daniel Rittschof, Maria Salta, Federica Ragazzola, Claire Hellio
Stress factors associated with climate change affect the growth and productivity of microbes (Rajkumar et al. 2013) and production of bioactive compounds (Hasegawa et al. 2005; Yang et al. 2007). Temperature has a substantial impact on microbial growth (Price and Sowers 2004). Elevated temperature accelerates the growth of mesophiles and slows the growth of psychrophiles and alters the interactions between bacteria and their hosts (White et al. 1991; Wahl et al. 2012). In the case of marine pathogens, elevated temperature increased growth, virulence and antimicrobial resistance (Kimes et al. 2012; Abdallah et al. 2014). For example, at 28°C the infection rate and attachment of the coral pathogen Vibrio shiloi increased, while at the lower temperatures (∼16°C) bacterial adhesion and growth in the tissues of the host coral Oculina patagonica was minimal and did not cause bleaching (Toren et al. 1998; Kushmaro et al. 2001). Virulence factors involved in motility, host degradation, secretion, antimicrobial resistance and transcriptional regulation were found to be up-regulated in the pathogen Vibrio coralliilyticus at temperatures above 27°C (Kimes et al. 2012).
Are infectious diseases and microbiology new fields for thermal therapy research?
Published in International Journal of Hyperthermia, 2018
Deniz Gazel, Mehmet Yılmaz
In classical microbiology, micro-organisms are grouped into categories according to their temperature ranges for growth. These are psychrophiles (<20 °C), mesophiles (20–45 °C), thermophiles (40–80 °C) and extreme thermophiles (about 100 °C). For any organism, the minimum and maximum growth temperatures define the range over which growth is possible. Growth is slower at low temperatures because enzymes work less efficiently and also because lipids tend to harden and there is a loss of membrane fluidity. Growth rates increase with temperature until the optimum temperature is reached, and then the rate falls again. The optimum and limiting temperatures for an organism are a reflection of the temperature range of its enzyme systems, which in turn are determined by their three-dimensional protein structures. Once the optimum value is passed, the loss of activity caused by denaturation of enzymes causes the rate of growth to fall away sharply [31]. Bacteriostatic antibiotics like macrolides and tetracyclines inhibit the growth of bacteria but do not kill [32]. Similarly, hyperthermia may act on pathogens by inhibiting their growth.
Evaluation of the antimicrobial mechanism of biogenic selenium nanoparticles against Pseudomonas fluorescens
Published in Biofouling, 2023
Ying Xu, Ting Zhang, Jiarui Che, Jiajia Yi, Lina Wei, Hongliang Li
Refrigerated food is now playing an important role in people’s life. Pseudomonas fluorescens are dominant psychrophilic bacteria causing spoilage of refrigerated food (Remenant et al. 2015), which are gram-negative, straight rod-shaped (0.7–0.8 μm wide and 2.3–2.8 μm long), asporogenic, and bipolar flagellation. Under cold chain conditions (≤4 °C) the hydrolysis of some endogenous proteases can facilitate the growth and reproduction of bacteria, thus reducing the quality of perishable foods such as dairy products, fish, or shrimp (Jaspe et al. 2000; Wang et al. 2018; Carminati et al. 2019), and ultimately leading to the decline of food safety and economic value. In clinical research, when endotoxin produced and released by P. fluorescens enters the human blood, it will cause a series of symptoms such as intravascular coagulation and infectious shock (Gao et al. 2015). Therefore, it is necessary to inhibit the growth of P. fluorescens in foods.