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In this paper, a downstream process for purification of 1,3-propanediol from glycerol-based fermentation broth was investigated. The purification of 1,3-propanediol from fermentation broth was achieved by a process combining microfiltration, charcoal treatment, vacuum distillation, and silica gel chromatography. The broth was first filtered through hollow fiber cartridge, wherein 98.7% of biomass was removed. Soluble proteins and other color impurities in the broth were removed by the use of activated charcoal at optimal concentration of 30 g l(-1) where the soluble proteins in the broth decreased to 0.1 g l(-1) (96.0% protein loss). The obtained broth when concentrated by vacuum distillation resulted in the crystallization of inorganic salts. Subsequently, 1,3-propanediol was purified by gradient chromatography using silica gel as a stationary phase and mixture of chloroform and methanol as a mobile phase. Finally, with the optimal flow rate of 10 ml min(-1) and loading amount of 80 ml, the yield of 1,3-propanediol achieved was 89%. The overall yield of 1,3-propanediol using the proposed procedure was 75.47%. The developed method was found to be a simple, rapid, and efficient procedure for the purification of 1,3-propanediol from fermentation broth.

Aims:  The traditional uses of the aerial parts of fresh Plectranthus cylindraceus by the Dhofaris in Oman were investigated on the basis of antimicrobial properties and composition of its herb oil. Methods and Results:  The minimal inhibitory concentration (MIC) values of the herb oil of P. cylindraceus against human pathogenic bacteria and yeast were assessed using the broth microdilution method, and the percentage growth inhibition of fungi was determined according to the poisoned food technique. The oil exhibited good activity against Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis and Candida albicans with MIC values in the range of 7·8–62·5 μg ml−1 and also inhibited the growth of Microsporum canis, Microsporum gypseum, Trichophyton rubrum, Alternaria alternata, Bipolaris sp., Curvularia lunata, Fusarium oxysporum and Stemphylium solani for about a week at 250 μg ml−1. The two most abundant components of the oil were identified as carvacrol (46·8%) and α‐terpinolene (18·2%) based on gas chromatography‐mass spectra (GC‐MS) and 13C nuclear magnetic resonance (NMR) analyses. Conclusions:  The oil has a pleasant odour and showed broad spectrum antimicrobial activity. Such bioactivity could be attributed in part to carvacrol. Significance and Impact of the Study:  This study has demonstrated the broad spectrum antimicrobial activity of the herb oil of P. cylindraceus as well as the organic composition of this plant extract. This study provides scientific insight into the ancient practice of utilizing P. cylindraceus as a fragrant disinfectant.