Production, characterization, and antitumor efficiency of l-glutaminase from halophilic bacteria

Background Halophiles are an excellent source of enzymes that are not only salt stable, but also can withstand and carry out reaction efficiently under extreme conditions. l-glutaminase has attracted much attention with respect to proposed applications in several fields such as pharmaceuticals and food industries. The aim of the present study was to investigate the anticancer activity of l-glutaminase produced by halophilic bacteria. Various halophilic bacterial strains were screened for extracellular l-glutaminase production. An attempt was made to study the optimization, purification, and characterization of l-glutaminase from Bacillus sp. DV2-37. The antitumor activity of the produced enzyme was also investigated. Results The potentiality of 15 halophilic bacterial strains isolated from the marine environment that produced extracellular l-glutaminase was investigated. Bacillus sp. DV2-37 was selected as the most potent strain and optimized for enzyme production. The optimization of fermentation process revealed that the highest enzyme activity (47.12 U/ml) was observed in a medium supplemented with 1% (w/v) glucose as a carbon source, 1% (w/v) peptone as a nitrogen source, 5% (w/v) NaCl, the initial pH was 7.0, at 37 °C, using 20% (v/v) inoculum size after 96 h of incubation. The produced crude enzyme was partially purified by ammonium sulfate precipitation and dialysis. Of the various parameters tested, pH 7, 40 °C, and 5% NaCl were found to be the best for l-glutaminase activity. The enzyme also exhibited high salt and temperature stability. The antitumor effect against human breast (MCF-7), hepatocellular (HepG-2), and colon (HCT-116) carcinoma cell lines revealed that l-glutaminase produced by Bacillus sp. DV2-37 showed potent cytotoxic activity of all the tested cell lines in a dose-dependent manner with an IC50 value of 3.5, 3.4, and 3.8 µg/ml, respectively. Conclusions The present study proved that l-glutaminase produced by marine bacteria holds proper features and it has a high potential to be useful for many therapeutic applications.

Optimization of fermentation conditions in Barbari bread based on mixed whole flour (barley and sprouted wheat) and sourdough

The purpose of this study was to use a mixture of whole wheat–barley flour mixture in the preparation of traditional Iranian bread (Barbari) in the optimum condition of fermentation to benefit from all available nutrients. In this study, bread parameters such as specific volume, porosity, textural characteristics, zinc, iron, phytic acid and organoleptic properties were investigated. In this research, different percentages of sourdough (15–30%) and fermentation time (30 – 120 min) were applied. Results showed that the phytic acid content significantly decreased ( p < 0.05) (0.23 – 0.14) by increasing sourdough and fermentation time, which result in increasing in zinc (17.49 – 22.89%) and iron (36.44 – 45.32%) content. Both the sourdough content and fermentation time parameters had a significant effect ( p < 0.05) on the better porosity (9.05 – 13.50%) and overall acceptability of bread (2.15 – 3.85). The hardness, gumminess, chewiness, porosity, phytic acid and overall acceptance parameters were used to optimize the fermentation conditions of Barbari bread by response surface methodology using a central composite design. Optimal conditions for the production of Barbari bread were 29.53% sourdough and 120 min fermentation time. Under optimal conditions, the overall acceptance, hardness, porosity, chewability, gumminess and phytic acid were 3.84, 60.81 N, 14.09%, 302.01 N/mm, 41.37 N and 0.15%, respectively.

Optimization of Fermentation Conditions for Production of Hungarian Sour Cherry Spirit Using Response Surface Methodology

Pálinka is a traditional fruit spirit and a kind of gastronomic heritage in Hungary. In Pálinka production, fermentation is one of the most important processes affecting the quality and yield of spirits. Based on single-factor and three-factor influence level tests by following the Plackett–Burman design, the fermentation process from sour cherry juice concentrate and Saccharomyces cerevisiae by using Response Surface Methodology (RSM) coupled with the central composite rotatable design was investigated to optimize fermentation conditions through three variables in a defined range of temperature (1525 °C), pH (2.753.75), and total soluble solid (1830 °Brix). After eight fermentation days, production yields of alcohol and volatile compounds were a maximum of 9.02% v/v and 337.37 mg/L at an optimized temperature of 24.71 °C, pH of 3.25, and total soluble solid of 22.49 Brix. The GC-FID analysis results showed 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and ethyl acetate were considered the major aroma compound in the cherry spirits. These results provided important information in serving the basic to develop standard fruit spirits production from sour cherry.

Optimization of Fermentation Conditions for Carrageenase Production by Cellulophaga Species: A Comparative Study

Carrageenases appear in various species of marine bacteria and are widely used for the degradation of carrageenans, the commercially significant sulphated polysaccharides. The carrageenase production ability of six different Cellulophaga species was identified, with ι-carrageenase being the most abundant carrageenolytic enzyme. C. algicola was the most potent strain, followed by C. fucicola and C. geojensis, whereas C. pacifica was the least effective carrageenase producer among the studied strains. The enzyme production was maximized using the one-factor-at-a-time optimization method. The optimal incubation temperature was identified as 25 °C and the incubation time was set as 48 h for all tested species. The optimal medium composition for Cellulophaga strains was determined as 30 g/L sea salt, 1.4 g/L furcellaran, and 3 g/L yeast extract. An ultrafiltered enzyme extracted from C. algicola had the highest activity at around 40 °C. The optimal pH for enzymatic degradation was determined as 7.8, and the enzyme was fairly stable at temperatures up to 40 °C.

Optimization of Fermentation Process for Improving Soy Isoflavones Aglycone Content in Bean Dregs by Lactobacillus plantarum PL70a

Aglycone-type soy isoflavones have higher biological activity than glycoside-type soy isoflavones. Bean dregs are rich in glycoside-type soy isoflavones. In order to improve the biological activity of soy isoflavones in bean dregs, the Lactobacillus plantarum PL70a was screened and the fermentation process of converting glycoside-type soy isoflavones into aglycone-type in bean dregs was optimized by single-factor experiments and the response surface methodology. The optimal fermentation process was as follows: (NH4)2SO4 was added in an amount of 0.17%, glucoamylase was added in an amount of 0.87%, inoculation amount was 17%, sucrose was added in an amount of 1.3%, and fermentation time was 3 days. Under this process, the content of aglycone-type soy isoflavones in bean dregs significantly increased. Trypsin inhibitors and antigen proteins were almost removed. The fermentation process provides a good reference for the low-cost processing of high-quality soy isoflavone aglycone food.

Optimization of Pre-Inoculum, Fermentation Process Parameters and Precursor Supplementation Conditions to Enhance Apigenin Production by a Recombinant Streptomyces albus Strain

Streptomyces albus J1074-pAPI (Streptomyces albus-pAPI) is a recombinant strain constructed to biotechnologically produce apigenin, a flavonoid with interesting bioactive features that up to now has been manufactured by extraction from plants with long and not environmentally friendly procedures. So far, in literature, only a maximum apigenin concentration of 80.0 µg·L−1 has been obtained in shake flasks. In this paper, three integrated fermentation strategies were exploited to enhance the apigenin production by Streptomyces albus J1074-pAPI, combining specific approaches for pre-inoculum conditions, optimization of fermentation process parameters and supplementation of precursors. Using a pre-inoculum of mycelium, the apigenin concentration increased of 1.8-fold in shake flask physiological studies. In 2L batch fermentation, the aeration and stirring conditions were optimized and integrated with the new inoculum approach and the apigenin production reached 184.8 ± 4.0 µg·L−1, with a productivity of 2.6 ± 0.1 μg·L−1·h−1. The supplementation of 1.5 mM L-tyrosine in batch fermentations allowed to obtain an apigenin production of 343.3 ± 3.0 µg·L−1 in only 48 h, with an increased productivity of 7.1 ± 0.1 μg·L−1·h−1. This work demonstrates that the optimization of fermentation process conditions is a crucial requirement to increase the apigenin concentration and productivity by up to 4.3- and 10.7-fold.