In this work, a simple, safe and rapid method for enumerating nitrifying bacteria was used as an alternative to traditional harmful chemical methods. The enumeration of nitrifying bacteria was based upon the change of color of the growth media containing pH indicators in response to acid production during nitrification. The oxidation of ammonia to strong acids by nitrifiers leads to pH decrease, which can be detected by pH indicators such as methyl orange (MO), bromocresol green (BCG), methyl red (MR), bromothymol blue (BTB), and phenol red (PhR) using the Most Probable Number (MPN) technique. The use of these pH indicators revealed a higher estimate than the classical chemical methods in all tested samples. Ammonium oxidizer counts always exceeded those of nitrite oxidizers in the surveyed environments. The time required for the detection of growth (positive tubes in MPN) was descending in the following order: MO, BCG, MR, BTB and PhR. The time to detection was shorter for ammonium oxidizers than for nitrite oxidizers. Generally, nitrifier counts were very low in soils compared with farmyard manure or sewage effluent. Incubation periods for both organisms differed from 4 to 8 weeks depended upon the indicator used. Finally, it could be concluded that the use of pH indicators, especially phenol red, as proposed in this study was accurate, sensitive and successfully applicable for the enumeration of nitrifiers in different environments.
Background: To address the predictors of hemodynamic instability (HI) related to carotid artery stenting (CAS) and evaluate the association between HI and periprocedural adverse outcomes. Methods: This study comprised all consecutive patients who underwent CAS for atherosclerotic carotid artery stenosis from March 2014 to May 2018. A standardized dose of atropine (0.4 mg) was given prior to stent deployment. Changes in heart rate, blood pressure, and neurological status were monitored and recorded. Potential predictors of HI were tested in multivariate analysis using binary logistic regression model. Results: A total of 728 patients were enrolled. Two hundred twenty seven patients (31.2%) developed periprocedural HI. The presence of hypertension (OR, 2.037; 95% CI, 1.292-3.211; P = 0.0022), symptomatic carotid lesions (OR, 1.704; 95% CI, 1.057-2.747; P = 0.0287), right sided lesions (OR, 3.090; 95% CI, 1.934-4.935; P ≤ 0.0001), hyperechoic/calcified plaques (OR, 2.195; 95% CI, 1.458-3.304; p P = 0.0002), and longer lesions (OR, 1.043; 95% CI, 1.012-1.076; P = 0.0072) were significant predictable factors for the occurrence of HI. On the other hand, smoking was significantly associated with a 48.1% decrease in risk of development of HI (OR, 0.519; 95% CI, 0.358-0.754; P = 0.0006). There were no statistically significant differences in periprocedural morbidity or mortality between patients with and without HI. Conclusion: HI occurs in a considerable percentage of patients undergoing CAS. Hypertension, right sided, symptomatic carotid lesions, calcified plaques, and longer lesions were shown to be independent risk factors for the development of periprocedural HI. Conversely, smoking demonstrated a protective effect. HI did not appear to predispose to periprocedural adverse events.
One hundred and twenty four plant extracts were evaluated for their antimicrobial a c t i v i t y a g a i n s t f o u r p a t h o g e n i c b a c t e r i a (Staphylococcus
The increasing consumer awareness of the risks derived not only from food borne pathogens, but also from the artificial chemical preservatives used to control them, has led to an increased interest in food -grade preservatives of biological origin. In this respect, special interest has been focused on the antimicrobial bacteriocins and the lactic acid bacteria producing them which are considered safe biopreservatives. In the present study, sixty nine lactobacillus strains isolated from retail samples of local foods and dairy products were screened for bacteriocin production Of the 47 Lactobacillus isolates found to be bacteriocin-like substances producers, five best strains which showed the strongest antibacterial activity against E.coli; Listeria monocytogenes; Bacillus cereus; Salmonella enteritides; and Staphylococcus aureus, were selected and identified, among these isolates, two were found belong to Lb. paracasei subsp. paracasei. The bacteriocin-like substances (BLS) produced by these strains were tested for characteristics that could determine their usefulness as food biopreservatives. The two BLS retained most of their bacterial activity even after autoclaving and after extended refrigerated and freezing storage, as well as after exposure to organic solvents or surfactants, and they remained functional over a wide pH rang of 3.0 to 12.0 and tolerated up to 20.0% sodium chloride. In addition they exhibited broad antimicrobial spectra against not only G + bacteria but also against Gbacteria and yeasts. These results suggest that BLS produced by two local Lactobacillus strains has an application potential as food biopreservatives, and may be used as alternatives or complimentary for antibiotics. Keywords: Bacteriocins, Lactobacillus paracasei subsp. paracasei, antibiotics. INTRODUCTIONQuality and safety of foods have always a significant public health concern. Although various methods are employed for the preservation of foods, an increasingly health conscious public may seek to avoid foods that have undergone extensive processing or which contain artificial chemical preservatives. This provided an increased interest in food-grade preservatives of biological origin. In this respect, special interest has been focused on bacteriocins produced by bacteria.Bacteriocins are defined as ribosomally synthesized peptides or proteins with antagonistic activity against species genetically closely related (De Vuyst and leroy, 1994), and some of them are inhibitory towards food spoilage and food borne pathogenic bacteria (Zamfir et al., 1999). The aim of using bacteriocins to improve quality and safety of foods has stimulated intensive research efforts in recent years (Deegan , 2006). Although bacteriocins are produced by many Gram-positive and Gramnegative bacteria, those produced by lactic acid bacteria (LAB) are of particular Gamal-Eldin,H. et al.
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