Bacterial cellulose is a biological polymer with a variety of extraordinary properties which make it a functional material in different industrial fields. This work aimed at monitoring the effects of three different organic acids and nanoparticles on the production, water holding capacity and structural characteristics of bacterial cellulose. Different concentrations of organic acids and nanoparticles were used to detect their effect on cellulose synthesis, and the crystalline structure of produced bacterial cellulose was analyzed by FTIR. The results showed that acetic acid has the best effect on bacterial cellulose production with productivity of 1.23 g L-1 (1.8 – fold higher than control) followed by CuO nanoparticle, and lactic acid exhibits the minimum effect (0.74 g L-1). Oleic acid could improve bacterial cellulose production 1.5 fold higher than the control. From our FTIR results, the highest total crystalline index value (4.3) is related to the control bacterial cellulose representing the highest degree of crystallinity. Although acetic acid increases the production, but it has a negative effect on the total crystalline index values. The water holding capacity values of bacterial celluloses confirmed this assumption. Addition of CuO nanoparticle not only promotes production of cellulose but also does not change the crystallization so much compared to the control. Therefore we can use these data for improvement of bacterial cellulose production due to its great potential for biotechnological application.
Baluchi sheep is the dominant fat-tail breed in Iran. We studied the microbial communities in the rumen of four Baluchi lambs fed a high concentrate conventional diet, the partial ribosomal rRNA of bacterial and archaeal were amplified by polymerase chain reaction (PCR) using DNA extracted from rumen samples. The amplicons were sequenced using 454 Titanium pyrosequencing and the data analyzed using the QIIME software package. The results indicated that Prevotella, a member of the phylum Bacteroidetes, dominated and its relative abundance accounted for 70.7 ± 2.68 % of the bacteria. Firmicutes was the second most abundant phylum, and Selenomonas and unclassified Veillonellaceae and Lachnospiraceae were present at relative abundances of 2.4 ± 0.62, 2.1 ± 0.21 and 1.9 ± 0.58 %, respectively. Entodinium was the most abundant genus of protozoa, comprising 61.6 ± 4.52 % of the protozoal community, followed by Polyplastron and Isotricha with relative abundances of 18.2 ± 2.35 and 9.7 ± 5.62 %, respectively. More than half of the archaeal community (53.3 ± 1.87 %) was composed of members of the Methanobrevibacter gottschalkii clade. The second and third most dominant archaea were members of the order Methanomassiliicoccales (28.3 ± 5.23 %) and Methanobrevibacter wolinii and relatives (8.5 ± 4.26 %). Based on this, rumen microbes of Baluchi lambs fed a total-mixed rations diet were similar to rumen microbes of ruminants fed similar diets in the other geographic regions around the world.
Cellulases with capability to have enzymatic functions at low pH and high temperature are important and include considerable portion of industrial enzymes. Endo-1,4-β-glucanase is one of the three cellulolytic enzymes in a triplet catalytic system that required for extracellular cellulose hydrolysis. In this study, the sampling was performed from four hot springs in north and northwest of Iran and the screening and identification of acid-stable and thermostable of endo-1,4-β-glucanase producing bacteria were investigated. Endo-1,4-β-glucanase of the isolated strains were determined by qualitative Congo-Red staining as well as quantitative Carboxymethylcellulose/Dinitrosalicylic acid methods as indicators of cellulase activity. Three isolates out of twelve initially selected bacteria, showed noticeable endo-1,4-β-glucanase activity, including Paenibacillus sp. ASh4 , Bacillus sp. AGh1 and Bacillus sp. AG2 with 90%, 77% and 45% residual activity at pH=4 and 60oC after three hours. Molecular identification of the bacteria was carried out using 16S rDNA partial sequencing, in which two isolates belonged to Bacillus sp. and one to Paenibacillus sp.. The results shown that the isolated acido-thermotolerant Bacillus spp. and Paenibacillus sp. had the capability to produce proper acid-stable and thermostable endoglucanase. These isolate also may be even considering as candidates for satisfactory production for other thermostable metabolites with further biotechnological applications.
Starch debranching enzymes that merely hydrolyze α-(1→6) glycosidic linkages are classified into isoamylases (EC 126.96.36.199) and pullulanases (EC 188.8.131.52). An exception to this definition would be amylopullulanase, a type of pullulanase that is capable of cleaving both α-(1→4) and α-(1→6) linkages. Amylopullulanases are in demand in liquid sugar industries to generate glucose and some other starch derivatives. Pullulanases can be used in conjunction with amylases to improve sugar availability during sugar syrup production. Here, a thermophilic Cohnella sp. A01 amylopullulanase (EC 184.108.40.206) gene, namely Coh4159, was PCR amplified and cloned in pET-26b(+) and transformed into BL21(DE3). Recombinant Coh4159 was heterologously expressed in the presence of 0.5 mM IPTG and purified via affinity chromatography, and further characterized. Enzyme activity was demonstrated via zymogram analysis in the presence of pullulan. The enzyme had a hydrolytic effect on pullulan with Vmax = 2.85 µmol.min-1 and Km = 0.5 mM. Temperature optima and pH were 60 ˚C and 6.0. In which the enzyme kept its activity at wide pH (4-9) and temperature (30-70 ˚C) ranges. The recombinant enzyme kept 50% of its activity for 60 min, 100 min and 120 min when incubated at 80, 70 and 60 ˚C, respectively. Amongst metal ions tested, Mn2+, and Ca2+ have improved the enzyme activity both at 5 and 10 mM. The results promise the capability of producing a commercial industrial enzyme, well-suited to liquid sugar syrup industry specification.
Abstract Microalgae biomass production and optimization is necessary to overcome food security problems and address environmental topic as well as high-value compounds production. In this investigation the influence of three culture media (BBM, BG-11 and Guillard f/2) on the growth and biomass production of the Picochlorum sp. RCC486 microalgae was evaluated. One- way ANOVA with Tukey’s HSD and Fisher’s LSD tests were used to test the effect of different culture media on optical density. Then the maximum optical density and biomass production by Picochlorum sp. RCC486 was evaluated using response surface methodology. A historical data of response surface methodology was used to find the optimum response, which yields the highest biomass production. Microalgal growth in Guillard f/2 medium reached highest cell count in the considered time period and the microalgae presented highest biomass production in comparison with other two culture media (BBM and BG-11). Additionally, biomass productivity(58 mg L-1d-1 ), specific growth rate (0.681d-1), dry weight (1.516 g L-1) and cell density(52.9 ×106 cells mL-1) were highest in comparison with other two culture media. The predicted optical density and biomass production using historical data design were close to their experimental values corresponding to 1.50313 and 1.976gL-1 respectively. while the concentrations of nitrogen source and phosphorus source were achieved in concentrations of 1345.55 mg L−1, 6.983 mg L−1 respectively. Under the optimum condition, the biomass yield was1.961 gL-1 which is 0.76% less than the predicted value. Also the study reported that the biomass production of Picochlorum sp. RCC486 improved from 1.516 g L-1 in defined Guillard f/2 medium to 1.961 g L-1 in modified Guillard f/2 medium resulting 22.69% increase. Thus, Picochlorum sp. RCC486 biomass content could be enhanced by optimizing nitrogen and phosphorus concentrations.
Cedar and elm woods were investigated for the microbial production of xanthan gum using a commercial strain of Xanthomonas campestris. However, the yields of xanthan gum from untreated woods were inefficient. Thus, dilute phosphoric acid (1-2% w/v) pretreatment at elevated temperatures (140-180 °C) for 10-20 min and concentrated phosphoric acid (85% w/v) pretreatment at 60 °C for 1-3 h were applied to increase production yields. Concentrated acid pretreatment resulted in the highest yields of 9.9 and 10.4 g xanthan gum per 100 g of raw cedar and elm wood, respectively, whereas the untreated woods yielded 2.0 and 2.4 g xanthan gum per 100 g of raw woods. Dilute acid pretreatment was not as efficient as concentrated acid pretreatment, resulting in 4.2 and 5.2 g xanthan gum per 100 g of cedar and elm, respectively. Consequently, the woods are suitable substrates for xanthan gum production after pretreatment with concentrated phosphoric acid at 160 °C for 1 h. The quality of produced xanthan gum was also compared with a commercial xanthan gum using Fourier transform infrared spectroscopy, and the results indicated that the produced xanthan gum was similar to the commercial product. Although the pretreatments presented in this study increased the xanthan gum yield up to fourfold, it was at the expense of increasing pretreatment costs. This research provides the basis for the economic analysis required for the commercial implementation of these pretreatments.
Advanced Research in Microbial Metabolite and Technology,
Volume 1, Issue 1, Pages 65-70