scholarly journals Effect of Nickel as Stress Factor on Phenol Biodegradation by Stenotrophomonas maltophilia KB2

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6058
Author(s):  
Agnieszka Gąszczak ◽  
Elżbieta Szczyrba ◽  
Anna Szczotka ◽  
Izabela Greń
Keyword(s):  
Bacterial Growth ◽  
Stenotrophomonas Maltophilia ◽  
Substrate Inhibition ◽  
Nickel Concentration ◽  
Bacterial Growth Rate ◽  
Phenol Biodegradation ◽  
Experimental Database ◽  
Batch Bioreactor ◽  
Initial Phenol Concentration ◽  
As Stress

This study focuses on the phenol biodegradation kinetics by Stenotrophomonas maltophilia KB2 in a nickel-contaminated medium. Initial tests proved that a nickel concentration of 33.3 mg·L−1 caused a cessation of bacterial growth. The experiments were conducted in a batch bioreactor in several series: without nickel, at constant nickel concentration and at varying metal concentrations (1.67–13.33 g·m−3). For a constant Ni2+ concentration (1.67 or 3.33 g·m−3), a comparable bacterial growth rate was obtained regardless of the initial phenol concentration (50–300 g·m−3). The dependence µ = f (S0) at constant Ni2+ concentration was very well described by the Monod equations. The created varying nickel concentrations experimental database was used to estimate the parameters of selected mathematical models, and the analysis included different methods of determining metal inhibition constant KIM. Each model showed a very good fit with the experimental data (R2 values were higher than 0.9). The best agreement (R2 = 0.995) was achieved using a modified Andrews equation, which considers the metal influence and substrate inhibition. Therefore, kinetic equation parameters were estimated: µmax = 1.584 h−1, KS = 185.367 g·m−3, KIS = 106.137 g·m−3, KIM = 1.249 g·m−3 and n = 1.0706.

scholarly journals Simplified Approach to Predict Food Safety through the Maximum Specific Bacterial Growth Rate as Function of Extrinsic and Intrinsic Parameters

2021 ◽  
Vol 5 (2) ◽  
pp. 22
Author(s):  
Pedro D. Gaspar ◽  
Joel Alves ◽  
Pedro Pinto
Keyword(s):  
Growth Rate ◽  
Food Safety ◽  
Information And Communication Technologies ◽  
Bacterial Growth ◽  
Low Cost ◽  
Extrinsic Factors ◽  
Bacterial Growth Rate ◽  
Modeling Tools ◽  
Simplified Approach ◽  
Food Safety And Quality

Currently, we assist the emergence of sensors and low-cost information and communication technologies applied to food products, in order to improve food safety and quality along the food chain. Thus, it is relevant to implement predictive mathematical modeling tools in order to predict changes in the food quality and allow decision-making for expiration dates. To perform that, the Baranyi and Roberts model and the online tool Combined Database for Predictive Microbiology (Combase) were used to determine the factors that define the growth of different bacteria. These factors applied to the equation that determines the maximum specific growth rate establish a relation between the bacterial growth and the intrinsic and extrinsic factors that define the bacteria environment. These models may be programmed in low-cost wireless biochemical sensor devices applied to packaging and food supply chains to promote food safety and quality through real time traceability.

scholarly journals Microbiological quality of non-sterile pharmaceuticals in Egypt

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Nourhan Mahrous Ahmed Salem ◽  
Mohamed Abbas Elbarrawy ◽  
Nashwa Fawzy Abd El Moez Azzam
Keyword(s):  
Bacterial Growth ◽  
Stenotrophomonas Maltophilia ◽  
Microbiological Quality ◽  
Pseudomonas Stutzeri ◽  
Dosage Forms ◽  
Aeromonas Salmonicida ◽  
Acceptable Limit ◽  
Organoleptic Characteristics

Abstract Background The context and purpose of the study are as follows: Drug-borne infections may arise from non-adherence to strict microbiological quality of pharmaceuticals products. Moreover, presence of exceeding levels of microorganisms in non-sterile pharmaceuticals may lead to change of their organoleptic characteristics and loss of effectiveness. The aim of the study is to evaluate the microbiological quality of commonly used non-sterile pharmaceuticals in Alexandria, Egypt. Results Average microbiological quality of the studied products, where 17.03% and 19.23 % of samples had exceeded the maximum acceptable limit of TAMC and TYMC, respectively. No E. coli was isolated from oral products. None of S. aureus nor P. aeruginosa were isolated from topical products. Bacterial growth was recovered from 19 (10.44%) of the studied 182 samples, four Bacillus spp. had been recovered from topical products, two P. aeruginosa isolates were recovered from tablets and other two were isolated from syrups dosage forms. Other isolates were Pseudomonas stutzeri, Stenotrophomonas maltophilia, Acinetobacter Achromobacter denitrificans, Ochrobactrum anthropic and Aeromonas salmonicida. Conclusion Average microbiological quality of the tested pharmaceuticals used in Alexandria.

Effect of Tannins on the In Vitro Growth of Escherichia coli O157:H7 and In Vivo Growth of Generic Escherichia coli Excreted from Steers

2007 ◽  
Vol 70 (3) ◽  
pp. 543-550 ◽  
Author(s):  
BYENG R. MIN ◽  
WILLIAM E. PINCHAK ◽  
ROBIN C. ANDERSON ◽  
TODD R. CALLAWAY
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Bacterial Growth ◽  
Escherichia Coli O157 ◽  
Tannin Extract ◽  
Bacterial Growth Rate ◽  
Linear Effect ◽  
E Coli

The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement of optical density at 600 nm during anaerobic culture in tryptic soy broth at 37°C, was reduced (P < 0.05) with as little as 400 μg of either tannin extract per ml of culture fluid. The addition of 200, 400, 600, 800, and 1,200 μg of tannins per ml significantly (P < 0.01) reduced the specific bacterial growth rate when compared with the nontannin control. The specific growth rate decreased with increasing dose levels up to 800 μg of tannins per ml. Bacterial growth inhibition effects in chestnut tannins were less pronounced than in mimosa tannins. Chestnut tannin extract addition ranged from 0 to 1,200 μg/ml, and a linear effect (P < 0.05) was observed in cultures incubated for 6 h against the recovery of viable cells, determined via the plating of each strain onto MacConkey agar, of E. coli O157:H7 strains 933 and 86-24, but not against strain 6058. Similar tests with mimosa tannin extract showed a linear effect (P < 0.05) against the recovery of E. coli O157:H7 strain 933 only. The bactericidal effect observed in cultures incubated for 24 h with the tannin preparations was similar, although it was less than that observed from cultures incubated for 6 h. When chestnut tannins (15 g of tannins per day) were infused intraruminally to steers fed a Bermuda grass hay diet in experiment 2, fecal E. coli shedding was lower on days 3 (P < 0.03), 12 (P = 0.08), and 15 (P < 0.001) when compared with animals that were fed a similar diet without tannin supplementation. It was concluded that dietary levels and sources of tannins potentially reduce the shedding of E. coli from the gastrointestinal tract.

scholarly journals Predictive Growth Modeling of Listeria monocytogenes in Rice Balls and Its Risk Assessment

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Seoungsoon Yeo ◽  
Misook Kim
Keyword(s):  
Risk Assessment ◽  
Listeria Monocytogenes ◽  
Bacterial Growth ◽  
Storage Temperature ◽  
Soy Sauce ◽  
Coefficient Of Determination ◽  
Growth Data ◽  
Bacterial Growth Rate ◽  
Microbial Risk ◽  
Life Years

This study aimed to investigate the growth of Listeria monocytogenes in rice balls and to conduct its microbial risk assessment based on the Korean dietary pattern. Each tuna or ham rice ball was mixed with mayonnaise, soy sauce, or gochujang, a Korean traditional fermented red peeper paste, which was artificially contaminated with L. monocytogenes and then stored at 7°C–25°C to assess bacterial growth. Growth data were analyzed using three primary models (the Huang, Baranyi, and Gompertz models), and the growth pattern was found to fit well to the Baranyi model based on the following five statistical criteria: root mean square error (0.38–0.56), Akaike’s information criterion (−51.55–−26.99), coefficient of determination (0.72–0.97), bias factor (0.97–1.01), and accuracy factor (1.06–1.18). The effects of temperature on bacterial growth rate and lag time were evaluated using the square root model. The minimum growth temperature for L. monocytogenes in tuna or ham rice balls was the lowest when they were mixed with mayonnaise (−9.44°C or −15.37°C, respectively). Risk assessment using FDA-iRISK showed that tuna or ham rice balls mixed with gochujang exhibited the highest microbial risk among all the rice balls tested, regardless of the storage temperature. Tuna or ham rice balls mixed with gochujang had the highest disability-adjusted life years per year (0.015) followed by ham rice balls mixed with soy sauce (0.011–0.015) or mayonnaise (0.006–0.015) and then tuna rice balls mixed with soy sauce (0.006–0.008) or mayonnaise (<0.001). In conclusion, our results, determined using predictive growth models, allow the assessment of potential risk ranking associated with the consumption of rice balls contaminated with L. monocytogenes based on the number of illnesses experienced per serving and the disease burden.

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