Whey proteins as multifunctional food materials: Recent advancements in hydrolysis, separation, and peptidomimetic approaches.

Whey protein derived bioactives, including α-lactalbumin, ß-lactoglobulin, bovine serum albumin, lactoferrin, transferrin, and proteose-peptones, have exhibited wide ranges of functional, biological and therapeutic properties varying from anticancer, antihypertensive, and antimicrobial effects. In addition, their functional properties involve gelling, emulsifying, and foaming abilities. For these reasons, this review article is framed to understand the relationship existed in between those compound levels and structures with their main functional, biological, and therapeutic properties exhibited either in vitro or in vivo. The impacts of hydrolysis mechanism and separation techniques in enhancing those properties are likewise discussed. Furthermore, special emphasize is given to multifunctional effects of whey derived bioactives and their future trends in ameliorating further food, pharmaceutical, and nutraceutical products. The underlying mechanism effects of those properties are still remained unclear in terms of activity levels, efficacy, and targeted effectiveness. For these reasons, some important models linking to functional properties, thermal properties and cell circumstances are established. Moreover, the coexistence of radical trapping groups, chelating groups, sulfhydryl groups, inhibitory groups, and peptide bonds seemed to be the key elements in triggering those functions and properties. Practical Application: Whey proteins are the byproducts of cheese processing and usually the exploitation of these food waste products has increasingly getting acceptance in many countries, especially European countries. Whey proteins share comparable nutritive values to milk products, particularly on their richness on important proteins that can serve immune protection, structural, and energetic roles. The nutritive profile of whey proteins shows diverse type of bioactive molecules like α-lactalbumin, ß-lactoglobulin, lactoferrin, transferrin, immunoglobulin, and proteose peptones with wide biological importance to the living system, such as in maintaining immunological, neuronal, and signaling roles. The diversification of proteins of whey products prompted scientists to exploit the real mechanisms behind of their biological and therapeutic effects, especially in declining the risk of cancer, tumor, and further complications like diabetes type 2 and hypertension risk effects. For these reasons, profiling these types of proteins using different proteomic and peptidomic approaches helps in determining their biological and therapeutic targets along with their release into gastrointestinal tract conditions and their bioavailabilities into portal circulation, tissue, and organs. The wide applicability of those protein fractions and their derivative bioactive products showed significant impacts in the field of emulsion and double emulsion stabilization by playing roles as emulsifying, surfactant, stabilizing, and foaming agents. Their amphoteric properties helped them to act as excellent encapsulating agents, particularly as vehicle for delivering important vitamins and bioactive compounds. The presence of ferric elements increased their transportation to several metal-ions in the same time increased their scavenging effects to metal-transition and peroxidation of lipids. Their richness with almost essential and nonessential amino acids makes them as selective microbial starters, in addition their richness in sulfhydryl amino acids allowed them to act a cross-linker in conjugating further biomolecules. For instance, conjugating gold-nanoparticles and fluorescent materials in targeting diseases like cancer and tumors in vivo is considered the cutting-edges strategies for these versatile molecules due to their active diffusion across-cell membrane and the presence of specific transporters to these therapeutic molecules.

Valorization of frying oil waste for biodetergent production using Serratia marcescens N2 and gamma irradiation assisted biorecovery.

BACKGROUND: The complexity, toxicity and abundance of frying oil waste (FOW) render it difficult to be degraded biologically. The aim of the present work was to valorize FOW and investigate the potential use of the produced biosurfactant by Serratia marcescens N2 (Whole Genome sequencing accession ID SPSG00000000) as a biodetergent. RESULTS: Serratia marcescens N2 demonstrated efficient valorization of FOW, using 1% peptone, 20% FOW and 8% inoculum size. Gene annotation showed the presence of serrawettin synthetase indicating that the produced biosurfactant was serrawettin. Zeta potential and Fourier Transform Infrared (FTIR) spectroscopy indicate that the biosurfactant produced was a negatively charged lipopeptide. The biosurfactant reduced the surface tension of water from 72 to 25.7 mN/m; its emulsification index was 90%. The valorization started after 1 h of incubation and reached a maximum of 83.3%. Gamma radiation was used to increase the biosurfactant yield from 9.4 to 19.2 g/L for non-irradiated and 1000 Gy irradiated cultures, respectively. It was noted that the biorecovery took place immediately as opposed to overnight storage required in conventional biosurfactant recovery. Both chemical and functional characteristics of the radiation induced biosurfactant did not change at low doses. The produced biosurfactant was used to wash oil stain; the highest detergency reached was 87% at 60 °C under stirring conditions for 500 Gy gamma assisted biorecovery. Skin irritation tests performed on experimental mice showed no inflammation. CONCLUSION: This study was able to obtain a skin friendly effective biodetergent from low worth FOW using Serratia marcescens N2 with 83% efficient valorization using only peptone in the growth media unlike previous studies using complex media. Gamma radiation was for the first time experimented to assist biosurfactant recovery and doubling the yield without affecting the efficiency.

Comparative transcriptome analysis for the biosynthesis of antioxidant exopolysaccharide in Streptococcus thermophilus CS6.

BACKGROUND: Food grade Streptococcus thermophilus produces biological exopolysaccharides (EPSs) with great potential with respect to catering for higher health-promoting demands; however, how S. thermophilus regulates the biosynthesis of EPS is not completely understood, decelerating the application of these polymers. In our previous study, maltose, soy peptone and initial pH were three key factors of enhancing EPS yield in S. thermophilus CS6. Therefore, we aimed to investigate the regulating mechanisms of EPS biosynthesis in S. thermophilus CS6 via the method of comparative transcriptome and differential carbohydrate metabolism. RESULTS: Soy peptone addition (58.6 g L-1 ) and a moderate pH (6.5) contributed to a high bacterial biomass and a high EPS yield (407 mg L-1 ). Maltose, soy peptone and initial pH greatly influenced lactose utilization in CS6. Soy peptone addition induced a high accumulation of mannose and arabinose in intracellular CS6, differential monosaccharide composition (mannose, glucose and arabinose) in EPS and high radical [2,2-diphenyl-1-picrylhydrazyl, superoxide and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] scavenging activities. Carbohydrate transportation, sugar activation and eps cluster-associated genes were differentially expressed to regulate EPS biosynthesis. Correlation analysis indicated high production of EPSs depended on high expression of lacS, galPMKUTE, pgm, gt2-5&4-1 and epsLM. CONCLUSION: The production of antioxidant EPS in S. thermophilus CS6 depended on the regulation of galactose metabolism cluster and eps cluster. The present study recommends a new approach for enhancing EPS production by transcriptomic regulation for further food and health application of EPS. © 2022 Society of Chemical Industry.

The effect of carbon, nitrogen and iron ions on mono-rhamnolipid production and rhamnolipid synthesis gene expression by Pseudomonas aeruginosa ATCC 15442.

Pseudomonas spp. are the main producers of rhamnolipids. These products have applications in pharmaceuticals, cosmetics, food industry and bioremediation. The biosynthesis of rhamnolipids is influenced by nutrient composition, pH and temperature. In this study, the impact of nutrients on the expression levels of rhamnolipid synthesis genes was evaluated in P. aeruginosa ATCC 15442. Glucose and glycerol were used as carbon sources; while, NaNO3, NH4NO3 and yeast extract/peptone were employed as nitrogen sources. The effect of different concentrations of Fe2+ and Fe3+ on rhamnolipid synthesis genes was also evaluated. Highest biosurfactant production was obtained in minimal medium supplemented with glucose, NaNO3 and Fe2+. Two rhamnolipid synthesis genes, rhlA and rhlB, were amplified with PCR. CapLC ESI-Ion trap-MS/MS detected only mono-rhamnolipid Rha-C10-C10 in the extract. Although similar induction levels were recorded in the presence of 0.05 g/L iron ions, the presence of Fe2+ resulted in higher expression levels than Fe3+ at concentrations equivalent to 0.025 and 0.075 g/L.

Potential antitumor activity of exopolysaccharide produced from date seed powder as a carbon source for Bacillus subtilis.

The major functions of Exopolysaccharide (EPS) include, preventing bacterial cells from desiccating and biofilm production to increase the colonization of bacterial cells. In the current study, a bacterial strain was isolated to produce EPS. Phylogenetic analysis of the isolated strain indicated it was related to Bacillus subtilis. The bacterium showed the ability to produce a new EPS using very cheap date seeds as a carbon source. Different conditions were studied to enhance exopolysaccharide production. Maximum total sugars (exopolysaccharide) were reached to 0.87 mM) at 20 g/lAjwadates seed (ADS). The maximum production was found to be 3.46 mM by addition of peptone as the main source of nitrogen with a concentration of 1.5 g/L. The optimal parameter values were temperature 37 °C, pH 6, incubation time 72 h and inoculum concentration 1 mL. The crude exopolysaccharide was purified by removing the cells, then the protein, then dialysis and finally ethanol precipitation of the exopolysaccharide. This method modification increased exopolysaccharide production to 0.6 g/L. The exopolysaccharide produced showed antitumor activity against Erlich tumor cells. It is promising for application on a large scale for different types of cancer cell lines.

Proteolytic activity of non-albicans Candida and Candida albicans in oral cancer patients.

Oral Candida infections can be life-threatening in medically compromised patients. In particular non-albicans Candida strains are virulent. However, our knowledge is sparse on how proteolytic these strains are in patients with oral cancer. Our study aimed to investigate differences in proteolytic activity of non-albicans Candida and Candida albicans isolated from oral cancer patients. The hypothesis was based on anticipated different invasive capacity of the strains. Clinical and reference yeast samples from our laboratory were used for analyses. Candida strains were grown in yeast peptone glucose and the activity of Candida proteinases of broken cell fractions were analysed by MDPF-gelatin zymography. Fluorometric assay was used to compare activities of proteolytic enzymes and degradation assays were performed using CLDN 4 and plasma fibronectin. Clear differences were seen in the proteolytic activity between the studied non-albicans Candida and C. albicans strains. C. tropicalis had the highest proteolytic activity followed by strains of C. krusei and C. glabrata. The results confirmed our study hypothesis by showing differences between the non-albicans Candida and Candida albicans strains studied. Higher proteolytic activity may thus have an effect on the virulence of non-albicans Candida strains in oral cancer patients.

Antioxidant Activity of Water Extract from Fermented Mycelia of Cordyceps sobolifera (Ascomycetes) in Caenorhabditis elegans.

This research aimed to evaluate the potential of Cordyceps sobolifera in mycelial biomass production via liquid culture and to assay the safety and determine the antioxidative and antiaging activities of Caenorhabditis elegans. A C. sobolifera isolate was cultured using the one-factor-at-a-time method to illustrate its carbon and nitrogen requirements. To assess safety, we determined the lethality, locomotion behavior, and reproduction of C. elegans cultured on a mycelial water extract (MWE) containing nematode growth medium (NGM). To investigate antiaging activity, C. elegans treated with MWE was incubated on NGM plates. The lethality was recorded throughout the whole life cycle. To identify antioxidant activity, C. elegans treated with MWE was exposed to paraquat, causing superoxide conditions. The results showed that C. sobolifera was favored by glucose and peptone as carbon and nitrogen sources, respectively. MWE was considered to be safe, as no abnormal behaviors were observed in C. elegans. Compared with nematodes pretreated with no MWE but with water instead, MWE at 1.0 mg/mL significantly prolonged the mean lifespan of C. elegans by 24%. We observed an obvious dose-effect relation between concentration and mean lifespan. The effective antioxidant activity was recorded at the high concentration of MWE. These findings demonstrate the potential antiaging and antioxidant properties of C. sobolifera as functional food and dietary supplement.

Urea enhances cell lysis of Schizosaccharomyces pombe ura4 mutants.

Cell lysis is induced in Schizosaccharomyces pombe ∆ura4 cells grown in YPD medium, which contains yeast extract, polypeptone, and glucose. To identify the medium components that induce cell lysis, we first tested various kinds of yeast extracts from different suppliers. Cell lysis of ∆ura4 cells on YE medium was observed when yeast extracts from OXOID, BD, Oriental, and Difco were used, but not when using yeast extract from Kyokuto. To determine which compounds induced cell lysis, we subjected yeast extract and polypeptone to GC-MS analysis. Ten kinds of compounds were detected in OXOID and BD yeast extracts, but not in Kyokuto yeast extract. Among them was urea, which was also present in polypeptone, and it clearly induced cell lysis. Deletion of the ure2 gene, which is responsible for utilizing urea, abolished the lytic effect of urea. The effect of urea was suppressed by deletion of pub1, and a similar phenotype was observed in the presence of polypeptone. Thus, urea is an inducer of cell lysis in S. pombe ∆ura4 cells.

Growth of Campylobacter incubated aerobically in fumarate-pyruvate media or media supplemented with dairy, meat, or soy extracts and peptones.

The ability of Campylobacter to grow aerobically in media supplemented with fumarate-pyruvate or with dairy, meat, or soy extracts or peptones was examined. Optical densities (OD) of Campylobacter cultured in basal media, media supplemented with fumarate-pyruvate or with 1.0, 2.5, 5.0, or 7.5% beef extract was measured. Growth was also compared in media supplemented with other extracts or peptones. Finally, cfu/mL of Campylobacter recovered from basal media or media supplemented with fumarate-pyruvate, casamino acids, beef extract, soytone, or beef extract and soytone was determined. Results indicated that OD of cultures grown in media supplemented with fumarate-pyruvate or with 5.0 or 7.5% beef extract were higher than OD of isolates grown in basal media or media supplemented with lower concentrations of beef extract. Highest OD were produced by isolates grown in media supplemented with beef extract, peptone from meat, polypeptone, proteose peptone, or soytone. Also, more cfu/mL were recovered from media with fumarate-pyruvate, beef extract, soytone, or beef extract-soytone than from basal media or media with casamino acids. Findings indicate that media supplemented with organic acids, vitamins, and minerals and media supplemented with extracts or peptones containing these metabolites can support aerobic growth of Campylobacter.

Effects of cultural medium on the formation and antitumor activity of polysaccharides by Cordyceps gunnii.

The effects of culture medium composition (i.e., carbon and nitrogen sources) on the growth of mycelia, molecular weight distribution and antitumor activity of intracellular polysaccharides (IPS) from Cordyceps gunnii were investigated. Sucrose and peptone were proved to be the best carbon and nitrogen sources for mycelia growth and remarkably improved IPS production. When the sucrose concentration was 2.0%, the mycelium yield reached up to 15.94±1.26 g/L, but with lower IPS yield; whereas the sucrose concentration was 4.5%, IPS yield reached to a maximum of 138.78±3.89 mg/100 mL. The effects of different carbon/nitrogen (C/N) ratios with equal amounts of carbon source matter on the mycelia and IPS formation were optimized. It found that the yield of mycelia and IPS were both reached to the highest at a C/N ratio of 10:3. In addition, the IPS had the highest macro molecular polysaccharide content and antitumor activity when sucrose concentration was 3.5% and the C/N ratio was 10:1.5. Thus, there was a positive correlation between molecular weight distribution and antitumor activity of IPS by C. gunnii.

Nanofiltration concentration of extracellular glutathione produced by engineered Saccharomyces cerevisiae.

This study aimed to optimize extracellular glutathione production by a Saccharomyces cerevisiae engineered strain and to concentrate the extracellular glutathione by membrane separation processes, including ultrafiltration (UF) and nanofiltration (NF). Synthetic defined (SD) medium containing 20 g L(-1) glucose was fermented for 48 h; the fermentation liquid was passed through an UF membrane to remove macromolecules. Glutathione in this permeate was concentrated for 48 h to 545.1 ± 33.6 mg L(-1) using the NF membrane; this was a significantly higher concentration than that obtained with yeast extract peptone dextrose (YPD) medium following 96 h NF concentration (217.9 ± 57.4 mg L(-1)). This higher glutathione concentration results from lower cellular growth in SD medium (final OD600 = 6.9 ± 0.1) than in YPD medium (final OD600 = 11.0 ± 0.6) and thus higher production of extracellular glutathione (16.0 ± 1.3 compared to 9.2 ± 2.1 mg L(-1) in YPD medium, respectively). Similar fermentation and membrane processing of sweet sorghum juice containing 20 g L(-1) total sugars provided 240.3 ± 60.6 mg L(-1) glutathione. Increased extracellular production of glutathione by this engineered strain in SD medium and subsequent UF permeation and NF concentration in shortend time may help realize industrial recovery of extracellular glutathione.

Enhanced production of prodigiosin by Serratia marcescens MO-1 using ram horn peptone

This work addresses the production of prodigiosin from ram horn peptone (RHP) using MO-1, a local isolate in submerged culture. First, a novel gram-negative and rod-shaped bacterial strain, MO-1, was isolated from the body of the grasshopper (Poecilemon tauricola Ramme 1951), which was collected from pesticide-contaminated fields. Sequence analysis of 16S rDNA classified the microbe as Serratia marcescens. The substrate utilization potential (BIOLOG) and fatty acid methyl ester profile (FAME) of S. marcescens were also determined. The effect of RHP on the production of prodigiosin by S. marcescens MO-1 was investigated, and the results showed that RHP supplementation promoted the growth of MO-1 and increased the production of prodigiosin. A concentration of 0.4% (w/v) RHP resulted in the greatest yield of prodigiosin (277.74 mg/L) after 48 h when mannitol was used as the sole source of carbon. The pigment yield was also influenced by the types of carbon sources and peptones. As a result, RHP was demonstrated to be a suitable substrate for prodigiosin production. These results revealed that prodigiosin could be produced efficiently by S. marcescens using RHP.

Viability and proliferation of L929, tumour and hybridoma cells in the culture media containing sericin protein as a supplement or serum substitute.

Cell cultures often require the addition of animal serum and other supplements. In this study, silk sericin, a bioactive protein, recovered from the waste of silk floss production was hydrolysed into three pepsin-degraded sericin peptides with different ranges of molecular mass. Normal animal cells, tumour cells and hybridoma cells were cultured systematically in FBS culture media containing sericin as a supplement or serum substitute. The culture test and microscopic observation of L929 cells showed that the smaller molecular weight of the degraded sericin is most suitable for cell culture. The cell culture results showed that with the degradation of sericin, for normal mouse fibroblast L929 cells, addition of 0.75 % sericin into FBS culture medium yields cell viability that is superior to FBS culture medium alone. When all serum was replaced by sericin, cell viability in the sericin medium could reach about one half of that in FBS medium. When in a medium containing a mixture of FBS: sericin (6:4, v/v), the cell culture effect is about 80 %. For the cultures of four tumour and one hybridoma cells, regardless of the molecular weight range, these degraded sericin peptides could substitute all serum in FBS media. The cell viability and proliferation of these tumour and hybridoma cells are equivalent or superior to that in FBS medium. In other words, cell viability and proliferation of these tumour and hybridoma cells in sericin media are more preferable to serum media. The mechanism of the sericin protein to promote cell growth and proliferation will be further investigated later.

Oligopeptides stimulate glucagon-like peptide-1 secretion in mice through proton-coupled uptake and the calcium-sensing receptor.

AIMS/HYPOTHESIS: Ingested protein is a well-recognised stimulus for glucagon-like peptide-1 (GLP-1) release from intestinal L cells. This study aimed to characterise the molecular mechanisms employed by L cells to detect oligopeptides. METHODS: GLP-1 secretion from murine primary colonic cultures and Ca(2+) dynamics in L cells were monitored in response to peptones and dipeptides. L cells were identified and purified based on their cell-specific expression of the fluorescent protein Venus, using GLU-Venus transgenic mice. Pharmacological tools and knockout mice were used to characterise candidate sensory pathways identified by expression analysis. RESULTS: GLP-1 secretion was triggered by peptones and di-/tripeptides, including the non-metabolisable glycine-sarcosine (Gly-Sar). Two sensory mechanisms involving peptide transporter-1 (PEPT1) and the calcium-sensing receptor (CaSR) were distinguishable. Responses to Gly-Sar (10 mmol/l) were abolished in the absence of extracellular Ca(2+) or by the L-type calcium-channel blocker nifedipine (10 µmol/l) and were PEPT1-dependent, as demonstrated by their sensitivity to pH and 4-aminomethylbenzoic acid and the finding of impaired responses in tissue from Pept1 (also known as Slc15a1) knockout mice. Peptone (5 mg/ml)-stimulated Ca(2+) responses were insensitive to nifedipine but were blocked by antagonists of CaSR. Peptone-stimulated GLP-1 secretion was not impaired in mice lacking the putative peptide-responsive receptor lysophosphatidic acid receptor 5 (LPAR5; also known as GPR92/93). CONCLUSIONS/INTERPRETATION: Oligopeptides stimulate GLP-1 secretion through PEPT1-dependent electrogenic uptake and activation of CaSR. Both pathways are highly expressed in native L cells, and likely contribute to the ability of ingested protein to elevate plasma GLP-1 levels. Targeting nutrient-sensing pathways in L cells could be used to mobilise endogenous GLP-1 stores in humans, and could mimic some of the metabolic benefits of bariatric surgery.

A new strategy for improved glutathione production from Saccharomyces cerevisiae: use of cysteine- and glycine-rich chicken feather protein hydrolysate as a new cheap substrate.

BACKGROUND: Glutathione (GSH) is composed of the amino acids glutamic acid, cysteine and glycine. This study investigated the usability of chicken feather protein hydrolysate (chicken feather peptone, CFP) as a substrate for GSH production from Saccharomyces cerevisiae. RESULTS: CFP was found to be rich in ash (36.7 g per 100 g), protein (61.1 g per 100 g) and minerals (S, P, K, Ca, Fe, Na and Mg). It also had high contents of cysteine and glycine. CFP augmented biomass and GSH production by 53 and 115% respectively compared with the control medium. The highest biomass (17.4 g l(-1)) and GSH (271 mg L(-1)) concentrations were attained in CFP medium. The second highest biomass (16.8 g l(-1)) and GSH (255 mg L(-1)) concentrations were obtained in fish peptone medium. It was assumed that the high mineral, cysteine and glycine contents of CFP were related to cell growth and GSH synthesis in S. cerevisiae. CONCLUSION: This is the first report on the effect of cysteine- and glycine-rich protein hydrolysates on GSH production from S. cerevisiae. In this regard, CFP was tested for the first time as a GSH production substrate. As an additional contribution, a new hydrolysis process was developed for the preparation of protein hydrolysates.

Aspergillus flavus grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis.

BACKGROUND: Aflatoxins (AFs) are highly carcinogenic compounds produced by Aspergillus species in seeds with high lipid and protein contents. It has been known for over 30 years that peptone is not conducive for AF productions, although reasons for this remain unknown. RESULTS: In this study, we showed that when Aspergillus flavus was grown in peptone-containing media, higher initial spore densities inhibited AF biosynthesis, but promoted mycelial growth; while in glucose-containing media, more AFs were produced when initial spore densities were increased. This phenomenon was also observed in other AF-producing strains including A. parasiticus and A. nomius. Higher peptone concentrations led to inhibited AF production, even in culture with a low spore density. High peptone concentrations did however promote mycelial growth. Spent medium experiments showed that the inhibited AF production in peptone media was regulated in a cell-autonomous manner. mRNA expression analyses showed that both regulatory and AF biosynthesis genes were repressed in mycelia cultured with high initial spore densities. Metabolomic studies revealed that, in addition to inhibited AF biosynthesis, mycelia grown in peptone media with a high initial spore density showed suppressed fatty acid biosynthesis, reduced tricarboxylic acid (TCA) cycle intermediates, and increased pentose phosphate pathway products. Additions of TCA cycle intermediates had no effect on AF biosynthesis, suggesting the inhibited AF biosynthesis was not caused by depleted TCA cycle intermediates. CONCLUSIONS: We here demonstrate that Aspergillus species grown in media with peptone as the sole carbon source are able to sense their own population densities and peptone concentrations to switch between rapid growth and AF production. This switching ability may offer Aspergillus species a competition advantage in natural ecosystems, producing AFs only when self-population is low and food is scarce.

Effect of soy and milk protein-related compounds on Listeria monocytogenes infection in human enterocyte Caco-2 cells and A/J mice.

Listeria monocytogenes causes listeriosis in humans, mainly through the consumption of ready-to-eat foods such as cheese. Immunocompromised persons, the elderly, and pregnant women and their fetuses or newborns are at the highest risk for the infection. We examined the effects of dietary milk-casein (MC) and soy-protein (SP), and their digested compounds tryptone (TP) and phytone peptone (PP), respectively, on L. monocytogenes invasion and infection in human enterocyte-like Caco-2 cells and A/J mice. Invasion into Caco-2 cells tended to be high with TP. In A/J mice orally infected with L. monocytogenes, viable numbers in the liver and spleen showed a tendency of decreasing with the 20% SP diet compared to the 20% MC diet. SP suppressed the inflammation marker tumour necrosis factor-α in spleen tissue. Furthermore, bacteria lipopolysaccharide (LPS)-stimulated nitric oxide (NO) secretion from murine macrophage RAW 264.7 cells was suppressed by PP more than TP. These results suggest that major dietary proteins might affect infection and inflammation by L. monocytogenes.

Bioresolution of benzyl glycidyl ether using whole cells of Bacillus alcalophilus.

The incubation of whole Bacillus alcalophilus cells grown on a mineral supplemented medium (MSM) containing 1% (w/v) sucrose as carbon source, 1.2% (w/v) tryptone as nitrogen source at pH 6.5 and temperature 30 °C in 24 h kinetically resolved benzyl glycidyl ether (1 mg/ml) to provide (S)-benzyl glycidyl ether with 30% ee and (R)-3-benzyloxypropane-1,2-diol with 40% ee.

Nutritional factors determining sclerotial formation of Polyporus umbellatus.

AIMS: To find out which nutritional condition is the determining factor for sclerotial formation of Polyporus umbellatus. METHODS AND RESULTS: The nutritional requirements of 15 carbohydrates, ten nitrogen compounds, eight vitamins and eight mineral elements were studied for their effects on mycelial growth and sclerotial formation of Polyporus umbellatus using the one-factor-at-a-time method. Only fructose could induce sclerotial formation of P. umbellatus. An additional test indicated that nitrogen source categories influenced sclerotial formation significantly and that peptone was found to be the best for sclerotial production. Through an orthogonal matrix test, the effects of carbon/nitrogen factors on sclerotial formation were found be in the order: fructose > interaction between fructose and peptone > peptone. The optimal concentration for sclerotial formation was determined to be 50.0 g l(-1) fructose and 4.0 g l(-1) peptone. CONCLUSIONS: Carbon source is the factor determining sclerotial formation of Polyporus umbellatus. Nitrogen source can influence such a morphological transformation significantly. The categories of vitamin and mineral element do not have relationship with the sclerotial formation. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides the preparatory knowledge for the completely artificial culture of Polyporus umbellatus for its sclerotium.

Pet secretion, internalization and induction of cell death during infection of epithelial cells by enteroaggregative Escherichia coli.

In an in vitro model using HEp-2 cells treated with purified plasmid-encoded toxin (Pet), we have identified morphological changes characterized by cell rounding and detachment after toxin internalization; these changes progress to cell death. However, these effects have not yet been shown to occur during the infection of epithelial cells by enteroaggregative Escherichia coli (EAEC). Here, we show that the secretion of Pet by EAEC is regulated at the transcriptional level, since secretion was inhibited in eukaryotic cell culture medium, although Pet was efficiently secreted in the same medium supplemented with tryptone. Inefficient secretion of Pet by EAEC in DMEM prevented cell detachment, whereas efficient Pet secretion in DMEM/tryptone increased cell detachment in a HEp-2 cell adherence assay. Interestingly, Pet toxin was efficiently delivered to epithelial cells, since it was internalized into epithelial cells infected with EAEC at similar concentrations to those obtained by using 37 microg ml(-1) purified Pet protein. Additionally, Pet was not internalized when the epithelial cells were infected with a pet clone, HB101(pCEFN1), unlike the wild-type strain, which has a high adherence capability. There is a correlation between Pet secretion by EAEC, the internalization of Pet into epithelial cells, cell detachment and cell death in EAEC-infected cells. The ratio between live and dead cells decreased in cells treated with wild-type EAEC in comparison with cells treated with an isogenic mutant in the pet gene, whereas the effects were restored by complementing the mutant with the pet gene. All these data indicate that Pet is an important virulence factor in the pathogenesis of EAEC infection.