Biodegradable and antimicrobial polymeric food packaging materials are very important because of environmental problems, for quality, and the shelf life of the product. The aim of this paper is to produce antimicrobial and biodegradable food packaging films with polycaprolactone (PCL). Using the amount of PCL (w/w) as the basis and to control the degradation time and to give antimicrobial properties, 0.4 wt% of organo nano clay (C) and 25, 50, and 75 wt% chitosan (K), and the use of glycerol monooleate (GMO) or oleic acid (OA) as a plastifier (5, 10, 20, and 30 wt%) are added and 12 polymeric composite films were prepared. The samples were coded as PCL (P), organo nanoclay (C), oleic acid (O), and glycerol monooleate (G). For example, P_C0.4_G5 refers to the PCL composite film containing 0.4 wt% clay and 5 wt% glycerol monooleate (G). The disc diffusion procedure with Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, and Candida albicans test microorganisms were used to evaluate the antimicrobial properties of the films. PCL_C0.4_O5, PCL_C0.4_G5, PCL_C0.4_G10_K25, PCL_C0.4_O10_K25, and PCL_C0.4_O20_K50 and neat chitosan films have antimicrobial properties. A small amount of organo nano clay, 0.4 wt%, has an antimicrobial effect on C. albicans. The PCL_C0.4_G10_K25 composite film has an antimicrobial effect on E. coli, P. aeruginosa, and C. albicans. Mechanical tests were performed, and it was observed that the mechanical properties of PCL composite films decrease with the addition of chitosan. J. VINYL ADDIT. TECHNOL., 24:376–387, 2018. © 2017 Society of Plastics Engineers
Cytotoxic and antimicrobial effects of Montivipera xanthina venom against LNCaP, MCF-7, HT-29, Saos-2, Hep3B, Vero cells and antimicrobial activity against selected bacterial and fungal species: Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, E. coli O157H7, Enterococcus faecalis 29212, Enterococcus faecium DSM 13590, Staphylococcus epidermidis ATCC 12228, S. typhimirium CCM 5445, Proteus vulgaris ATCC 6957 and Candida albicans ATCC 10239 were studied for evaluating the potential medical benefit of this snake venom. Cytotoxicity of venom was determined using MTT assay. Snake venom cytotoxicity was expressed as the venom dose that killed 50 % of the cells (IC50). The antimicrobial activity of venom was studied by minimal inhibitory concentration (MIC) and disc diffusion assay. MIC was determined using broth dilution method. The estimated IC50 values of venom varied from 3.8 to 12.7 or from 1.9 to 7.2 μg/ml after treatment with crude venom for 24 or 48 h for LNCaP, MCF-7, HT-29 and Saos-2 cells. There was no observable cytotoxic effect on Hep3B and Vero cells. Venom exhibited the most potent activity against C. albicans (MIC, 7.8 μg/ml and minimal fungicidal concentration, 62.5 μg/ml) and S. aureus (MIC, 31.25 μg/ml). This study is the first report showing the potential of M. xanthina venom as an alternative therapeutic approach due to its cytotoxic and antimicrobial effects.
In the present study, 120 yeast isolates from different sources (active sludge, soil, and wastewater samples obtained from petroleum refinery and soil contaminated by petroleum) were obtained. The yeast isolates were screened for lipase production and twelve of the isolates (D3, D17, D24, D27, D30, D38, D40, D42, D44, D46, D56, and D57) exhibited lipase activity. Molecular characterization of the yeasts showing the lipase production was performed with RFLP of ITS1-5.8S-ITS2 and 18S rRNA and sequence analysis of D1/D2 domain of 26S rRNA. The 26S rRNA sequencing revealed that four new strains, D38, D40, D44 and D57 identified as Rhodotorula slooffiae, Candida davisiana, Cryptococcus diffluens, and Cryptococcus uzbekistanensis, respectively, are lipase producing yeast species. This study is the first report showed lipase production by these species. The other lipase producing strains identified as Candida parapsilosis (D3), Rhodotorula muciloginosa (D17 and D42), Cryptococcus albidus (D24, D27, D30, and D56), and Wickerhamomyces anomalus (D46).
In this study, 65 yeast strains were isolated from different environmental samples contaminated with various petroleum hydrocarbons such as activated sludges and soil samples from automobile workshops. The yeast isolates were tested for biosurfactant production using various screening methods such as parafilm M test, oil displacement assay, drop collapse assay, determination of surface tension reduction, and emulsification index. Nineteen of the isolates were found positive for biosurfactant production and their molecular characterizations were carried out by sequencing analysis of the ITS1-5.8S-ITS2 region and D1/D2 domain of 26S rDNA. The results indicated that these strains were from a wide range of yeast genera including Rhodotorula, Candida, Yarrowia, Geotrichum, Galactomyces, and Cystobasidium. The studies to determine the emulsification index revealed that the biosurfactants produced by Yarrowia lipolytica strains (TEMGS33, TEMOS12, and TEMOS14) and Apiotrichum loubieri strain (TEMOS16) were the most potent and capable of forming stable emulsions with emulsion index (E ) up to 68%. In addition, quantitative measurements of the surface tension reduction of the biosurfactants produced by these strains were carried out by Du Noüy ring method. Biosurfactants produced from Yarrowia lipolytica strain TEMGS33 and Apiotrichum loubieri strain TEMOS16 gave the best results reducing the surface tension to 34.7 ± 1.15 and 35.3 ± 0.55 mN m , respectively. Based on these data, biosurfactants from Yarrawia lipolytica strains (TEMGS33, TEMOS12, and TEMOS14) and Apiotrichum loubieri strain (TEMOS16) showed promising results and might be implemented in numerous industrial fields such as bioremediation and food industry.
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