After cellulose, chitin is one of the most important polymers in crustaceans, insects, and fungi. Chitosan is one of the most important derivatives of chitin, which has important characteristics including degradability, non-toxicity, and biocompatibility antimicrobial and antioxidant properties.Chitosan was extracted from Penaeus semisulcatus shrimp using chemical methods and the degree of its austenitization was determined using a sub-red spectrophotometer and XRD. The nanoparticles were then synthesized using the ionic gelation method and analyzed through SEM. The antimicrobial effects of nanoparticles were also evaluated using antimicrobial tests on Listeria monocytogenes and Salmonella typhi.Nanoparticles have antimicrobial activity and can inhibit bacterial growth at different concentrations.Chitosan nanoparticles have an inhibitory effect on Listeria monocytogenes, which is a gram-positive bacterium.
Nickel oxide nanoparticles (NiO NPs) have received great interests in medical and biotechnological applications. However, their adverse impacts against biological systems have not been well-explored. Herein, the influence of NiO NPs on structural changes, heme degradation and aggregation of hemoglobin (Hb) was evaluated by UV-visible (Vis) spectroscopy, circular dichroism (CD) spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM), and molecular modeling investigations. Also, the morphological changes and expression of Bax/Bcl-2 mRNA in human lymphocyte cell exposed to NiO NPs were assayed by DAPI staining and quantitative real-time PCR (qPCR), respectively. The UV-Vis study depicted that NiO NPs resulted in the displacement of aromatic residues and heme groups and production of the pro-aggregatory species. Intrinsic and Thioflavin T (ThT) fluorescence studies revealed that NiO NPs resulted in heme degradation and amorphous aggregation of Hb, respectively, which the latter result was also confirmed by TEM study. Moreover, far UV-CD study depicted that NiO NPs lead to substantial secondary structural changes of Hb. Furthermore, near UV-CD displayed that NiO NPs cause quaternary conformational changes of Hb as well as heme displacement. Molecular modelling study also approved that NiO NPs resulted in structural alterations of Hb and heme deformation. Moreover, morphological and genotoxicity assays revealed that the DNA fragmentation and expression ratio of Bax/Bcl-2 mRNA increased in lymphocyte cells treated with NiO NPs for 24 hr. In conclusion, this study indicates that NiO NPs may affect the biological media and their applications should be limited.Communicated by Ramaswamy H. Sarma.
Polyhydroxybutyrate is a biodegradable plastic produced by some bacteria and can completely be replaced with petroleum based non-degradable plastics.This study was done to isolate and identify one local strain with a high-production ability for industrial purposes.The sampling from petrochemical wastewater was done. The existence of polyhydroxybutyrate in isolates was studied with Sudan Black staining. Using the Sudan Black B plate assay method and estimating produced PHB amount, the most potent isolate was chosen. This isolate was distinguished by morphological and biochemical methods and determining 16S rRNA gene sequencing. The final confirmation of polyhydroxybutyrate synthesis was done by FTIR and 1H NMR. To increase more production of polyhydroxybutyrate, the effect of different factors including carbon, nitrogen, pH, and temperature were assessed.Six bacterial isolates producing polyhydroxybutyrate were separated, which among them, one new strain of Bacillus megaterium named saba.zh was selected as better isolation. 16S rRNA nucleotide sequence of bacterium was assigned accession number: MN519999 in the NCBI database. The optimal conditions to increase the production of polyhydroxybutyrate, are using glucose as a carbon source, ammonium sulfate as the nitrogen source, in the condition with having pH 7 and temperature 30 °C. After optimizing, the production of PHB increased from 56.51% to 85.41%.This research indicated that Bacillus megaterium saba.zh, due to better polymer yield, is a potent PHB producer which can be used for PHB industrial production.
Abstract The full text of this preprint has been withdrawn by the authors due to author disagreement with the posting of the preprint. Therefore, the authors do not wish this work to be cited as a reference. Questions should be directed to the corresponding author.
Abstract This paper delves into the antimicrobial activity and identification of bioactive compounds of Amycolatopsis roodepoortensis strain EA7. Biochemical and molecular methods were utilized for the identification of actinomycetes. One strain displaying superior antimicrobial activity was chosen for the identification of bioactive compounds. The antimicrobial activity was thoroughly investigated. The analysis of the 16S rRNA gene revealed that strain EA7 belonged to the Amycolatopsis roodepoortensis specie with 99.63% confidence. The ethyl acetate extract exhibited the largest zone of inhibition against gram-positive pathogenic bacteria (25mm) using the disc diffusion method. In the MIC method, the ethyl acetate extract displayed the lowest MIC values ranging from 312.5 µg/mL (S. aureus PTCC 1112) to 1250 µg/mL (P. aeruginosa clinical and standard strain). However, the methanolic extract showed lower antimicrobial activity. In the GC-MS analysis, compounds were identified based on their percentage of area, retention time, molecular formula, molecular weight, and quality in the strain EA7 extract, with acetic acid, 2-methylpropyl ester (15.8%) being the major compound. In the LC-MS analysis, nine major compounds with anticancer and antimicrobial activity were identified. Among these, tetrangomycin, amycolactam, dihydroxybenzamide, and dipyrimycin A are compounds with potential anticancer activity, while tetracycline exhibits potential antimicrobial activity.
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