A comparative study between one-factor-at-a-time and minimum runs resolution-IV methods for enhancing the production of polysaccharide by Stenotrophomonas daejeonensis and Pseudomonas geniculate

Two bacterial strains were isolated from compost sample from Egypt and identified based on morphological and molecular characteristics using 16S rRNA sequence as Stenotrophomonas daejeonensis B14 and Pseudomonas geniculate Y8. Optimization of fermentation factors was performed by using one-factor-at-a-time (OFAT) and minimum runs resolution-IV statistical (Min Run Res IV) approaches. OFAT technique achieved the maximum polysaccharide dry weight at 30.1 and 25.3 g/L from S. daejeonensis B14 and P. geniculate Y8, respectively on medium containing 25% (w/v) blackstrap molasses (BSM) and 1.5 g/L corn steep liquor (CSL). The optimum pH was 6.5 and 7.5 for P. geniculate Y8 and S. daejeonensis B14, respectively. This medium inoculated with 5% (v/v) of standard inoculum of each strain individually, then incubated at 30 °C using shake flasks at 200 rpm for 96 h of the incubation period, respectively. Whereas, Min Run Res IV approach was recording that 3, among 8 factors had a significant effect on biopolymer production by both strains being fermentation time (72 h), BSM concentration (250 g/L), and shaking speed (at 250 rpm). This method resulted in a 7.3 and 9.2% increase in polysaccharide yield from S. daejeonensis B14 and P. geniculate Y8, respectively as compared to OFAT. The biopolymer was partially characterized according to physiochemical properties as follows; white colour crystalline, soluble in hot water, low viscosity and its contents of ash, total carbohydrate, total reducing sugar and total protein are ranged from 5.5 to 7.8%, 44.7 to 42.4%, 14.1 to 13.5%, 1.5 to 2.4%, respectively. Keywords: Biopolymer production, Pseudomonas geniculata, Stenotrophomonas daejeonensis, Min Run Res IV design, Polymer characterizatio

Antibacterial, antibiofilm and antitumor activities of grape and mulberry leaves ethanolic extracts towards bacterial clinical strains

The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured at concentrations of 0.01–2.56 mg/mL of grape and mulberry leaves ethanolic extracts. The MIC values were ranged from 0.08 to 0.16 mg/mL against Ps. aeruginosa Ps9, and 0.32 mg/mL against each of S. aureus St3, E. coli Ec3, and S. typhi Sa1. Whereas, the MBC values were ranged from 0.32 to 1.28 mg/mL of the tested extracts. The effects of the tested extracts were also studied representing the bactericidal effect of the grape extract with a ratio of 2 against all investigated isolates, except S. typhi Sa1. Whereas, the mulberry extract had a bactericidal effect towards S. aureus St3 and E. coli Ec3 with ratio of 2, and a bacteriostatic effect against Ps. aeruginosa Ps9 and S. typhi Sa1 with a ratio ≥4. The investigated bacteria found to have a strong ability to form biofilms with densities ranged from 0.67 to 0.80. Both tested extracts inhibited these biofilms with percentages ranged from 48 to 66% at sub-inhibitory concentrations (SICs) ranged from 0.04 to 0.16 mg/mL. In addition, the tested extracts have an excellent cytotoxic activity towards colon cancer cell lines (HCT-16). Five phenolic compounds detected in the tested extracts of grape and mulberry using high performance liquid chromatography (HPLC) after 9.53 min of the retention time. The phenolic compounds of both tested extracts were gallic, coumaric, ferulic, chlorogenic and caffeic with concentrations ranged from 1.28 to 6.56 µg/mL

Production of amylases from Bacillus amyloliquefaciens under submerged fermentation using some agro-industrial by-products

AbstractThirty-one bacterial isolates out of 133 isolates, were obtained from rhizosphere of Egyptian clover plants, and had variant capability for starch degradation on starch agar medium. The isolate E109 was the most potent being 72.5Uml−1 and 2.5 for amylase activity and starch hydrolysis ratio (SHR), respectively, at 50°C. The potent isolate E109 was identified based on phenotypic characteristics, phylogenetic positions based on 16S rRNA gene analysis and base sequences (submitted to NCBI Gen Bank). 16S rRNA gene analysis confirmed that this isolate belonged to the genus Bacillus and it was most closely related to B. amyloliquefaciens (95% similarity). For the production of amylases, nine agro-industrial residues were added as carbon sources to the basal medium. The medium supplemented with potato starchy waste as the sole carbon source enhanced the enzyme activity more than soluble starch as control for α, β and γ amylases activity, as it increased by B. amyloliquefaciens about 1.26 & 4 and 8-fold, respectively after 48h at 50°C using rotary shaker at 150rpm. B. amyloliquefaciens gave the maximum values of α, β and γ amylases activity on medium supplemented with 2% potato starchy waste after 30, 30 & 36h of fermentation periods at 50°C using shake flasks technique as a batch culture. These values were 155.2Uml−1 (R2=0.93), 1.0Uml−1 (R2=0.94) and 2.4Uml−1 (R2=0.95), respectively. It could be stated that productive medium supplemented with 2% potato starchy waste as a low price substrate could be more favorable than basal medium containing 1% starch for amylases production in submerged fermentation, as it increased α, β and γ amylase activity by 1.98, 7.69 and 12-fold than that produced in basal medium (control), respectively

Toxicity assessment of green synthesized Cu nanoparticles by cell-free extract of Pseudomonas silesiensis as antitumor cancer and antimicrobial

Spherical homogeneous 32 nm, protein coated Pseudomonas silesiensis strain A3 CuNPs was investigated for their cytotoxicity effect as well as antimicrobial and antitumor activity. CuNPs cytotoxicity was estimated using human normal lung cell lines (Wi38) against CuNPs with concentrations ranging from 25 to 150 μg/mL using neutral red uptake assay. The cytotoxicity study revealed that the bacterial CuNPs had an impact on Wi38 cell viability at concentrations of 25, 50, 100 and 150 μg/mL CuNPs were 95.8, 91.1, 89.2 and 82.3%, respectively, with a strong correlation coefficient (r = 0.94) and a CuNPs IC50 value of 1057.0 μg/mL. CuNPs exhibit a broad-spectrum antimicrobial activity against various microorganism species, including fungi and Gram positive and negative bacteria using the agar-well diffusion method. The findings revealed that the most sensitive pathogens were Staphylococcus aureus ATCC5638 and Aspergillus flavus ATCC 9643 which tended to have a high inhibition zone diameter (50 and 47 mm, respectively). The minimum inhibitory concentration (MIC) of CuNPs was 50 μg/mL. The minimum lethal concentration (MLC) values were 50 and 75 μg/mL for S. aureus ATCC 5638 and A. flavus ATCC 9643, respectively. MLC/MIC ratio was ≤2, suggesting the CuNPs had a bactericidal or fungicidal effect on both pathogenic strains. Results also indicated that bacterial CuNPs at varying concentrations of 25, 50, 100 and 150 μg/mL were such a good antitumor agent against A549 lung carcinoma cell lines with an IC50 value of 137.5 μg/mL and a cell viability of 89.3, 79.6, 64.9 and 44.1%, respectively. The results also suggested that the biosynthesized-CuNPs were an antimicrobial and anticancer agent that could be used in future in food preservation, biomedicine and pharmaceutical fields

An immobilized biosorbent from Paenibacillus dendritiformis dead cells and polyethersulfone for the sustainable bioremediation of lead from wastewater

Abstract Heavy metals, including lead, cause serious damage to human health and the surrounding environment. Natural biosorbents arise as environmentally friendly alternatives. In this study, two of the 41 isolates (8EF and 17OS) were the most efficient bacteria for growing on media supplemented with Pb2+ (1000 mg/L). At high concentrations up to 2000 mg/L, the pioneer isolate 17OS exhibited remarkable resistance to multiheavy metals. This isolate was identified as Paenibacillus dendritiformis 17OS and deposited in GenBank under accession number ON705726.1. Design-Expert was used to optimize Pb2+ metal removal by the tested bacteria. Results indicated that four of six variables were selected using a minimum-run resolution IV experimental design, with a significant affecting Pb2+ removal. Temperature and Pb2+ concentration were significant positive influences, whereas incubation period and agitation speed were significant negative ones. The tested strain modulated the four significant variables for maximum Pb2+ removal using Box–Behnken design. The sequential optimization method was beneficial in increasing biosorption by 4.29%. Dead biomass of P. dendritiformis 17OS was embedded with polyethersulfone to get a hydrophilic adsorptive membrane that can separate Pb2+ easily from aqueous solutions. SEM images and FT-IR analysis proved that the new biosorbent possesses a great structure and a lot of surface functional groups with a negative surface charge of − 9.1 mV. The removal rate of 200 mg/L Pb2+ from water reached 98% using 1.5 g/L of the immobilized biosorbent. The adsorption isotherm studies were displayed to determine the nature of the reaction. The adsorption process was related to Freundlich isotherm which describes the multilayer and heterogeneous adsorption of molecules to the adsorbent surface. In conclusion, dead bacterial cells were immobilized on a polyether sulfone giving it the characteristics of a novel adsorptive membrane for the bioremediation of lead from wastewater. Thus this study proposed a new generation of adsorptive membranes based on polyethersulfone and dead bacterial cells

Bioactivity of Organic Fermented Soymilk as Next-Generation Prebiotic/Probiotics Mixture

Fermented soymilk (soymilk yogurt) was made by fermenting soymilk with five probiotic bacterial strains (Lactobacillus plantarum ATCC 14917, Lactobacillus casei DSM 20011, Lactobacillus acidophilus ATCC 20552, Lactococcus thermophilus DSM 20259, and Bifidobacterium longum B41409) that were used as monocultures and combined with them as consortia cultures. Seven pathogenic strains, E. coli O157H7, S. aureus As4, S. typhimurium As3, S. shigae As2, L. monocytogenes As1, P. aeruginosa ATCC 27853, and B. cereus Dsmz 345, were used to study the antibacterial activity of fermented soymilk by agar well diffusion assay. Results indicated that Gram-negative pathogenesis was more sensitive to probiotic cultures than Gram-positive pathogenesis. E. coli O15H7, S. typhimirium As3, and Shigella shigae As2 were more sensitive to probiotic cultures, presenting inhibition zone diameters (IZA) ranging from 10 to 20 mm, 12 to 16 mm, and 10 to 16 mm, respectively. At the same time, P. aeruginosa Atcc 27853 showed the lowest (IZA), ranging from 3 mm to 8 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined at various concentrations of soymilk fermented by T1, T4, and T5, ranging from 0.031 mg/mL to 1 mg/mL against pathogenic bacterial strains. The sensory properties of FSM were evaluated, and sensory analysis during soymilk fermentation showed significant improvement. The effect of shelf life (storage period) on FSM quality and properties was evaluated; during shelf life (storage period), FSM saved its properties and quality after 28 days of cold storage. Finally, it was stated that the soymilk yogurt can be used as a substitute for buffalo and cow milk for therapeutic feeding in the future