Salmonella enterica serovar Typhi (S. Typhi) is strictly a human intracellular pathogen. It causes acute systemic (typhoid fever) and chronic infections that result in long-term asymptomatic human carriage. S. Typhi displays diverse disease manifestations in human infection and exhibits high clonality. The principal factors underlying the unique lifestyle of S. Typhi in its human host during acute and chronic infections remain largely unknown and are therefore the main objective of this study.
A series of physico-chemical quality (peel and pulp colours, pulp firmness, fruit pH, sugars and acids content, respiration rate and ethylene production) were conducted to study the optimum harvest periods (either week 11 or week 12 after emergence of the first hand) of Rastali banana (Musa AAB Rastali) based on the fruit quality during ripening.
Rubber latex effluent is a polluting source that has a high biochemical oxygen demand (BOD). It is estimated that about 100 million liters of effluent are discharged daily from rubber processing factories. Utilization of this effluent such as the use of a coupled system not only can reduce the cost of treatment but also yield a fermentation feedstock for the production of bioplastic. This study initially was carried out to increase the production of organic acids by anaerobic treatment of rubber latex effluent. It was found that through anaerobic treatment the concentration of organic acids did not increase. Consequently, separation of organic acids from rubber latex effluent by anion exchange resin was examined as a preliminary study of recovering acetic and propionic acids. However, the suspended solids (SS) content in the raw effluent was rather high which partially blocked the ion-exchange columns. Lime was used to remove the SS in the rubber latex effluent. After the lime precipitation process, organic acids were found to adsorb strongly onto the anion exchange resin. Less adsorption of organic acids onto the resin was observed before the lime precipitation. This was probably due to more sites being occupied by colloidal particles on the resin thus inhibiting the adsorption of organic acids. The initial concentration of organic acids in the raw effluent was 3.9 g/L. After ion exchange, the concentration of the organic acids increased to 27 g/L, which could be utilized for production of polyhydroxyalkanoates (PHA). For PHA accumulation stage, concentrated rubber latex effluent obtained from ion exchange resins and synthetic acetic acid were used as the carbon source. Quantitative analyses from fed batch culture via HPLC showed that the accumulation of PHA in Alcaligenes eutrophus was maximum with a concentration of 1.182 g/L when cultivated on synthetic acetic acid, corresponding to a yield of 87% based on its cell dry weight. The dry cell weight increased from 0.71 to 1.67 g/L. On the other hand, using concentrated rubber latex effluent containing acetic and propionic acids resulted in reduced PHA content by dry weight (14%) but the dry cell weight increased from 0.49 to 1.30 g/L. The results clearly indicated that the cells grow well in rubber latex effluent but no PHA was accumulated. This could be due to the high concentration of propionic acid in culture broth or other factors such as heavy metals. Thus further work is required before rubber latex effluent can be utilized as a substrate for PHA production industrially.
Carboxylic acid reductases (CARs) are attracting burgeoning attention as biocatalysts for organic synthesis of aldehydes and their follow-up products from economic carboxylic acid precursors. The CAR enzyme class as a whole, however, is still poorly understood. To date, relatively few CAR sequences have been reported, especially from fungal sources. Here, we sought to increase the diversity of the CAR enzyme class. Six new CAR sequences from the white-rot fungus Pycnoporus cinnabarinus were identified from genome-wide mining. Genome and gene clustering analysis suggests that these PcCAR enzymes play different natural roles in Basidiomycete systems, compared to their type II Ascomycete counterparts. The cDNA sequences of all six Pccar genes were deduced and analysis of their corresponding amino acid sequence showed that they encode for proteins of similar properties that possess a conserved modular functional tri-domain arrangement. Phylogenetic analyses showed that all PcCAR enzymes cluster together with the other type IV CARs. One candidate, PcCAR4, was cloned and over-expressed recombinantly in Escherichia coli. Subsequent biotransformation-based screening with a panel of structurally-diverse carboxylic acid substrates suggest that PcCAR4 possessed a more pronounced substrate specificity compared to previously reported CARs, preferring to reduce sterically-rigid carboxylic acids such as benzoic acid. These findings thus present a new functionally-distinct member of the CAR enzyme class.
Lactobacillus acidophilus is categorized as a probiotic strain because of its beneficial effects in human health and prevention of disease transmission. This study is aimed to characterize the probiotic potential of L. acidophilus 36YL originally isolated from the vagina of healthy and fertile Iranian women. The L. acidophilus 36YL strain was identified using 16S rDNA gene sequencing and characterized by biochemical methodologies, such as antibiotics susceptibility, antimicrobial activity, and acid and bile resistance. The bioactivity of the secretion of this strain on four human cancer cell lines (AGS, HeLa, MCF-7, and HT-29) and one normal cell line (HUVEC) was evaluated by cytotoxicity assay and apoptosis analysis. This newly isolated strain was found to exhibit notable probiotic properties, such as admirable antibiotic susceptibility, good antimicrobial activity, and favorable resistance to acid and bile salt. The results of bioactivity assessment demonstrated acceptable anticancer effects on the four tested cancer cell lines and negligible side effects on the assayed normal cell line. Our findings revealed that the anticancer effect of L. acidophilus 36YL strain secretions depends on the induction of apoptosis in cancer cells. L. acidophilus 36YL strain is considered as a nutraceutical alternative or a topical medication with a potential therapeutic index because of the absence of cytotoxicity to normal cells, but effective toxicity to cancer cell lines.