Expression of extracellular polysaccharides and proteins by clinical isolates of Pseudomonas aeruginosa in response to environmental conditions

Enhanced production of di-(2-ethylhexyl) phthalate (DEHP) by Bacillus subtilis AD35 using response surface methodology (RSM)

“…Following our previous work on DEHP production by a B. subtilis marine isolate [1], here, we were interested in optimizing the process parameters shaping the production of DEHP by B. subtilis AD35 under submerged fermentation. Optimization through fractional factorial design (FFD) and response surface methodology (RSM) is a common practice for quick screening and estimating the levels of variables giving maximum response using a mathematical model [9][10][11]. Here, we adopted FFD and RSM to boost the DEHP synthesis by B. subtilis AD35.…”

Kinetic studies on the expression of alginate and extracellular proteins by <i>Pseudomonas aeruginosa</i> FRD1 and PAO1

“…However, these studies have focused on host defence as a response to the treatment regardless of pathogen virulence. On the other hand, we have recently demonstrated through preliminary studies that the levels of magnesium sulfate, ferrous sulfate, ammonium sulfate, trace elements and phosphates in the surrounding environment have significant effects on the formation of alginate and/or extracellular proteins by P. aeruginosa strains in shake flask cultures (Lotfy et al, 2018). Consequently, it can be predicted that dealing with such factors as environmental variables can introduce information that help to decrease the virulence efficiency of the pathogen by interference with the ability of bacterial cells to form biofilms and/or to express extracellular proteinaceous virulence factors.…”

“…The used media included nutrient broth containing (g/l) beef extract (3.0) and peptone (5.0) for maintaining stock cultures and medium C (Mian et al, 1978) with previously described modifications (Lotfy et al, 2018) to be used as the experimental basal medium. Media were sterilized by autoclaving at 121∞C for 20 minutes.…”

“…However, these studies have focused on host protection rather than the virulence of the pathogen. Moreover, only a single study has been reported so far that has evaluated the boosting influence of MgSO 4 on the virulence effect of P. aeruginosa (Lotfy et al, 2018). On the other hand, new antibacterial strategies could be developed based on understanding the mechanisms by which P. aeruginosa synthesizes its virulence factors (Wang et al, 2015).…”

“…Recently, our preliminary studies demonstrated that the total levels of alginate and/or extracellular proteins produced in P. aeruginosa shake flask cultures are significantly affected by the concentrations of magnesium sulfate, ferrous sulfate, ammonium sulfate, trace elements and phosphates in the surrounding environment (Lotfy et al, 2018). Here, we are interested to investigate the regulatory effects of such environmental factors on the amounts of alginate and extracellular proteins with a special focus on: (1) monitoring the target products expressed per biomass unit rather than the total amounts produced in the culture; (2) performing the experiments under a controlled bioreactor condition to attain a consistent environment, when compared to shake flask cultures; and (3) investigating the kinetics of growth and synthesis of the target products as a function of the growth phase.…”