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This study was conducted to investigate the microbiological quality of raw cow's milk in a collection center in the city of Mashhad, Iran. A total of 19 raw cow's milk samples were collected and simultaneously analyzed for male-specific (F(+)) coliphage and Escherichia coli using culture-based methods and for enteric viruses by reverse transcriptase semi-nested PCR using primer sets specific for human norovirus Group I (HNV-GI), human norovirus Group II (HNV-GII), and enteroviruses (EV). Seven out of 19 (36.8%) raw milk samples tested positive for human noroviruses (HNV). The genotypes detected were HNV-GI and HNV-GII. Three positive samples contained both genotypes, and 2 samples were positive for either of HNV-GI and HNV-GII. No sample tested positive for EV. The correlation between the occurrence of HNV and the microbial indicators was studied. The statistical analysis using first- and second-order regression revealed that there is no correlation between F(+) coliphage and E. coli. Similarly, no correlation was noticed between the occurrence of F(+) coliphages and HNV. However, frequency distribution analysis indicated that 3 out of 4 (75%) of raw milk samples containing F(+) coliphage at a concentration higher than 10(4) pfu/100 ml were also positive for noroviruses. The limited data on the occurrence of noroviruses in raw milk suggest a poor sanitation and hygiene practices at the facility and indicate a possible correlation between the viral indicator at high concentration and human noroviruses; however, this analysis needs further investigation in a larger scale study.

Due to the increasing global demand for Gamma-aminobutyric acid (GABA) in the food and pharmaceutical industries, the expression of the recombinant Glutamate decarboxylase (GAD) and its industrial production is currently requested. Culture conditions were optimized to increase the expression level of the recombinant enzyme in different pH, temperature, incubation time, aeration levels, inoculation concentrations, concentrations of IPTG, and several carbon sources using the RSM based on a central composite design. According to the results of the quadratic regression equation, recombinant Escherichia coli BL21 (DE3) had the highest GAD expression at pH=7.2, aeration at about 120 rpm, inoculation concentrations of about 3% v/v, 2.25 mM IPTG, 37 °C, and 6 h of incubation time in the presence of 0.2% glucose. Using pure glucose as a carbon source on an industrial scale is not cost-effective for producing recombinant proteins. Therefore, using low-cost carbon sources such as corn syrup and molasses with concentrations of 1.5 and 5.65% (w/v) is an efficient method for the industrial production of recombinant GAD. The concentration of purified recombinant GAD in carbon sources of 0.2% glucose, 1.5 corn syrup and 5.65% molasses was 2.155, 2.07 and 1.96 mg/mL, respectively. In this way, the global need for GABA can be met by the industrial production of GAD. [ABSTRACT FROM AUTHOR]

Various studies have shown that natural colorants, in addition to their coloring attributes, have valuable biological effects such as antioxidant, anti‐inflammation, and anticarcinogenic properties. Moreover, their use as a food colorant can restrict the potential disadvantages of synthetic additives and turn foods into functional products. In this study, in vitro antimicrobial activities of two natural colorants of bixin and curcumin against some important foodborne pathogens: Staphylococcus aureus (S. aureus), Listeria innocua (L. innocua), and Escherichia coli (E. coli) were investigated by disk diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration values were determined by agar dilution and broth microdilution methods. The synergistic activity of the colorants against selected microorganisms was assayed by the checkerboard microdilution method. The results showed that the inhibitory effects of bixin against S. aureus were more pronounced than E. coli and L. innocua. The lowest concentration of curcumin (0.6 mg/mL) in the disk diffusion method was not inhibited by any tested bacteria. However, it was effective at the higher concentrations against three microorganisms, but its diameter of inhibition zones was lower than gentamicin in all concentrations. Synergetic effects were observed by curcumin and bixin combination against S. aureus (FICI ≤ 0.5), but they act as an antagonist against E. coli and L. innocua. The results of the synergy test were confirmed by the isobologram curves. [ABSTRACT FROM AUTHOR]

Gamma amino butyric acid (GABA) is used as drugs, food ingredients, and dietary supplements. l-glutamate is converted to GABA by the decarboxylation reaction, which is catalyzed by the glutamate decarboxylase (GAD). Escherichia coli is widely being used to express proteins. However, without appropriate signal peptide, it cannot be applied for secretory proteins. Selecting a suitable signal peptide (SP) is a critical step in the secretory production of different proteins. In silico identification of suitable SP is a reliable and cost-effective alternative to experimental approaches. In previous studies, the localization of proteins was not considered and the SPs of periplasmic, membranes and extracellular were compared. Therefore, this study aimed to predict the best SP for the expression of recombinant GAD in the outer membrane of E. coli only. Also, we compared twelve servers to evaluate protein localization, solubility, and secretory pathway. In the present study, 127 SPs were taken from the Signal Peptide database. The localization site, physico-chemical properties, location of cleavage sites, regions and D-score of them were determined by ProtComp, ProtParam, and SignalP 3.0 and 4.1 servers, respectively. To rank SPs based on the secretion properties, PRED-TAT and SignalP 5.0 webservers were used. Based on the results, the localization site of 13 SPs was in the outer membrane of E. coli. Among them, the most suitable candidates seemed to be torT with a reasonably high D-score, aliphatic index, and GRAVY, followed by ccmH and then pspE. TorT accelerates GAD scale-up production and might be useful in future experimental research. [ABSTRACT FROM AUTHOR]