Exopolysaccharide from Bacillus mojavensis DAS10-1; Production and Characterization

Among group of bacteria screened for exopolymer production, Bacillus species DAS10-1 producing exopolysaccharide was detected. The bacterial strain was isolated from indoor air of Dammam slaughterhouse, in KSA and identified based on 16S rRNA gene sequencing. Phylogenetic analysis revealed its closeness to Bacillus mojavensis. In comparison with static culture, shake culture recorded 27.9-fold increase. FT-IR Spectroscopy showed sharp bands at 3415.6, 2942.1, 1646.5, 1183.1 and 1111.8 cm-1 that are typical for carbohydrate. Furthermore, strong absorbance in 1200-950 cm”1 indicated polysaccharide nature of the polymer. Result of GPC indicated that weight average (Mw), number average (Mn) and size average molecular weight (Mz) for EPS polymer were 1151Da, 987Da and 1302Da, respectively. Maximum EPS yield (5.62 mg/mg) was reported during growth on M3 medium supplemented with C:N ratio of 4:1 for sucrose and ammonium sulfate, respectively. Supplementation of medium with trace element solution-I resulted in remarkable decrease in EPS yield (1.62 mg/mg). Maximum EPS production (63.02 mg/mg) was recorded during growth on synthetic medium M3 in presence of 20 g/L sucrose. Successful use of the agro-industrial carbon source date syrup or DEPS rather than sucrose might significantly lower process economy and increase promises for production of EPS on industrial scale

Enhanced production of poly glutamic acid by Bacillus sp. SW1-2 using statistical experimental design

Bacillus sp. SW1-2 producing poly glutamic acid (PGA), locally isolated from Eastern province in Saudi Arabia, was characterized and identified based on 16S rRNA gene sequencing. Phylogenetic analysis revealed its closeness to Bacillus megaterium. The homopolymer consists mainly of glutamic as indicated in the analysis of amino acid. Preliminary optimization of PGA production, through a series of one-variable-at-a-time (OVAT) experiments, revealed maximum PGA production of 10.5 (g/L). Statistically based experiments were applied to optimize culture conditions for production of PGA. Effect of 15 variables were examined for their significance on PGA production using Plackett-Burman factorial design. Among those variables; Na-citrate, (NH4)2SO4, glutamic acid and CaCl2.2H2O were most significant variables that encouraged PGA production, while those negatively affected were; glycerol, glucose and phosphate buffer. Significant parameters were further investigated using Box-Behnken design to define the optimal medium composition. Based on statistical analysis, maximal PGA production on optimized medium was 36.5 (g/L) which was more than 4-folds the basal production medium. Verification experiment was carried out to examine model validation and revealed more than 95% validity.Keywords: Poly glutamic acid, Bacillus megaterium, statistical experimental design, optimization, one-variable-at-a-time (OVAT)African Journal of Biotechnology Vol. 12(5), pp. 481-49

Dual-Functional Nanostructures for Purification of Water in Severe Conditions from Heavy Metals and <i>E. coli</i> Bacteria

Because of industrial water, many groundwater sources and other water bodies have a strongly acidic medium. Increased bacterial resistance against multiple antibiotics is one of the main challenges for the scientific society, especially those commonly found in wastewater. Special requirements and materials are needed to work with these severe conditions and treat this kind of water. In this trend, nanolayered structures were prepared and modified in different ways to obtain an optimum material for removing different kinds of heavy metals from water in severe conditions, alongside purifying water from a Gram-negative bacteria (E. coli), which is an indication for fecal pollution. An ultrasonic technique effectively achieved this dual target by producing nanolayered structures looking like nanotapes with dimensions of 25 nm. The maximum removal percentages of the heavy metals studied (i.e., iron (Fe), copper (Cu), chromium (Cr), nickel (Ni), and manganese (Mn)) were 85%, 79%, 68%, 63%, and 61%, respectively for one prepared structure. In addition, this nanostructure showed higher antimicrobial activity against the most common coliform bacterium, E. coli (inhibition zone up to 18.5 mm). This study introduces dual-functional material for removing different kinds of heavy metals from water in severe conditions and for treating wastewater for Gram-negative bacteria (E. coli)