Screening for potential probiotic from spontaneously fermented non-dairy foods based on in vitro probiotic and safety properties

The aim of this study was to screen potential probiotic lactic acid bacteria from Chinese spontaneously fermented non-dairy foods by evaluating their probiotic and safety properties. All lactic acid bacteria (LAB) strains were identified by 16S rRNA gene sequencing. The in vitro probiotic tests included survival under low pH and bile salts, cell surface hydrophobicity, auto-aggregation, co-aggregation, antibacterial activity, and adherence ability to cells. The safety properties were evaluated based on hemolytic activity and antibiotic resistance profile. The salt tolerance, growth in litmus milk, and acidification ability were examined on selected potential probiotic LAB strains to investigate their potential use in food fermentation. A total of 122 strains were isolated and identified at the species level by 16S rRNA gene sequencing and included 62 Lactobacillus plantarum, 40 Weissella cibaria, 12 Lactobacillus brevis, 6 Weissella confusa, and 2 Lactobacillus sakei strains. One W. cibaria and nine L. plantarum isolates were selected based on their tolerance to low pH and bile salts. The hydrophobicity, auto-aggregation, co-aggregation, and antagonistic activities of these isolates varied greatly. All of the 10 selected strains showed multiple antibiotic resistance phenotypes and no hemolytic activity. The highest adhesion capacity to SW480 cells was observed with L. plantarum SK1. The isolates L. plantarum SK1, CB9, and CB10 were the most similar strains to Lactobacillus rhamnosus GG and selected for their high salt tolerance and acidifying activity. The results revealed strain-specific probiotic properties were and potential probiotics that can be used in the food industry.     

In Vitro Assessment of Probiotic Potential of Saccharomyces Cerevisiae DABRP5 Isolated from Bollo Batter,a Traditional Goan Fermented Food

Bollo is a traditional Goan fermented food in which coarse wheat/wheat and finger millet is leavened with toddy. We here isolated 42 yeast strains from Bollo batter. Initial screening of the isolates with probiotic properties yielded four yeast isolates (DABRP1, DABRP2, DABRP5 and DABRP12). These isolates exhibited tolerance to high bile salt concentration and acidic pH and resistance to various antibiotics, which indicated their probiotic nature. All these yeast isolates were identified as Saccharomyces cerevisiae through D1D2-LSU-rDNA sequencing. These yeast isolates also showed higher percent hydrophobicity towards chloroform followed by n-hexadecane and o-xylene indicating their mucosal surface-adhesive property. To evaluate the safety of the isolates for them to be called as generally recognized as safe, the pathogenic behavior of the isolates determined through the in vitro hemolysis assay and evaluation of DNase and gelatinase activities. None of the isolates exhibited hemolysis or produced DNase or gelatinase and thus were considered potentially safe. In terms of beneficial effects, the most potent isolate S. cerevisiae DABRP5 showed antibacterial activity against the test pathogens. It also showed excellent antioxidant activity with DPPH free radical scavenging activity of 68.85 ± 0.69%, anti-inflammatory activity with 60.39 ± 0.34% inhibition of protein denaturation, and antidiabetic activity with 71.75 ± 0.45% inhibition of α-amylase activity. The isolate produced α-amylase, lipase, and β-galactosidase. The probiotic potential of the isolate S. cerevisiae DABRP5 was similar to that of the reference strain (Saccharomyces boulardii CNCM I-745) used in this study. The results thus indicate that yeast isolates from Bollo batter have probiotic potential.

     

Improving anti-hyperglycemic and anti-hypertensive properties of camu-camu (Myriciaria dubia Mc. Vaugh) using lactic acid bacterial fermentation

Camu-camu (Myriciaria dubia Mc. Vaugh) is a tropical fruit rich in phenolic antioxidants with diverse human health benefits. The aim of this study was to improve phenolic antioxidant–linked functionalities of camu–camu relevant for dietary management of early stages of type 2 diabetes (T2D) and associated hypertension using lactic acid bacterial (LAB) fermentation. Dried camu–camu powder combined with soymilk was fermented using two LAB strains, Lactobacillus plantarum & Lactobacillus helveticus individually and evaluated for total soluble phenolic content, total antioxidant activity, α-amylase, α-glucosidase, and angiotensin-I-converting enzyme (ACE) inhibitory activities using in vitro assay models. Overall, fermentation of camu–camu and soymilk combination with both LAB strains resulted in higher α-amylase, and α-glucosidase inhibitory activities, while total soluble phenolic content and antioxidant activity did not change significantly with fermentation. Improvement of ACE enzyme inhibitory activity was also observed when camu–camu (0.5 & 1%) and soymilk combination was fermented with L. plantarum. Therefore such safe and value added fermentation strategy with LAB can be used to improve human health relevant phenolic antioxidant profile in camu–camu and has relevance for designing innovative probiotic beverage to target improved food designs for dietary support for T2D and associated hypertension management.     

Functional properties of <Emphasis Type="Italic">Lactobacillus</Emphasis> strains isolated from dairy products

Twenty-four acid- and bile-tolerant lactobacilli isolates from dairy products were identified and further in vitro characterized for the presence of functional traits potentially useful for probiotic applications, which included desirable and undesirable traits, such as biofilm formation, ability to inhibit intestinal pathogens, antibiotic susceptibility, and enzyme activity. The majority of examined strains were susceptible to certain antimicrobial agents (streptomycin, gentamicin, clindamycin, erythromycin, tetracycline, quinupristin–dalfopristin), except for three strains of Lactobacillus rhamnosus with minimal inhibitory concentration levels for streptomycin higher than the microbiological breakpoints (≥32 μg/mL), which are considered as resistant. Undesirable traits such as α-chymotrypsin or N-acetyl-β-glucosaminidase activities were not detected, but low β-glucuronidase, and moderate and high β-glucosidase activities were recorded in nine strains, which were eliminated from further examination together with three isolates showing unsuitable antibiotic resistance. Of the remaining 12 isolates, 4 (Lactobacillus fermentum 202, Lactobacillus gallinarum 7001, L. rhamnosus 183, and Lactobacillus plantarum L2-1) manifested an outstanding potential to inhibit selected intestinal pathogens in an agar spot test, including Escherichia coli and Salmonella spp., and simultaneously demonstrated strong biofilm-forming capacity. In conclusion, the results of our in vitro experiments showed that the above four strains had a potential probiotic value and met the criteria to be identified as a possible probiotic microorganism, with the necessity of verification through well-designed in vivo experimental, clinical, and technological studies before the strains can be used as probiotics or as starter probiotic cultures.     

Biotechnological lycopene production by mated fermentation of <Emphasis Type="Italic">Blakeslea trispora</Emphasis>

A semi-industrial process (800-l fermentor) for lycopene production by mated fermentation of Blakeslea trispora plus (+) and minus (–) strains has been developed. The culture medium was designed at the flask scale, using a program based on a genetic algorithm; and a fermentation process by means of this medium was developed. Fermentation involves separate vegetative phases for (+) and (–) strains and inoculation of the production medium with a mix of both together. Feeding with imidazole or pyridine, molecules known to inhibit lycopene cyclase enzymatic activity, enhanced lycopene accumulation. Different raw materials and physical parameters, including dissolved oxygen, stirring speed, air flow rate, temperature, and pH, were checked in the fermentor to get maximum lycopene production. Typical data for the fermentation process are presented and discussed. This technology can be easily scaled-up to an industrial application for the production of this carotenoid nowadays widely in demand.     

Pectinolytic activity secreted by yeasts isolated from fermented citrus molasses

AIMS: The aim of this study was to obtain improved strains of pectinolytic yeasts adapted to the conditions of an industrial fermentation process, which was continuously operated to convert citrus molasses into ethanol. METHODS AND RESULTS: The starter yeast of the industrial fermentation process was a commercial baker's yeast, which was capable of growing without forming any secretion halo of pectinase activity on solid medium. Nevertheless, isolates showing secretion of pectinolytic activity on plates were obtained from the fermentation process. The secretion of pectin-degrading activity by isolates on plates was repressed by galactose and improved as the result of colony aging on polygalacturonic acid plates at 30 degrees C. Liquefaction of polygalacturonate gels as well as the splitting of the pectin-degrading activity into a wall-linked and a supernatant fraction were also observed when the starter yeast was propagated under agitation in liquid medium containing pectin. CONCLUSIONS: Isolates capable of secreting pectinolytic activity on plates were predominant at the end of the citrus molasses fermentation. Nevertheless, the sizes of the secretion haloes on plates were not necessarily an indication of the levels of pectinolytic activity secreted in the liquid medium. SIGNIFICANCE AND IMPACT OF THE STUDY: Improved pectinolytic strains of Saccharomyces can be used as a source of pectinases for a variety of applications. This organism also participates in plant deterioration processes.     

Probiotic Properties and Cellular Antioxidant Activity of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> MA2 Isolated from Tibetan Kefir Grains

Lactobacillus plantarum MA2 was isolated from traditional Chinese Tibetan kefir grains. Its antioxidant properties had been demonstrated in vitro and in vivo previously. In the present study, the probiotic characteristics of this strain were further evaluated by investigating its acid and bile salt tolerances, cell surface hydrophobicity, and autoaggregation, respectively. In addition, the cellular antioxidant activity (CAA) assay was applied to test the antioxidant capacity of the isolate in different growth phases. Same method was also used to evaluate the antioxidant capacity of its fermentation supernatant, cell-free extract, and intact cell quantitatively. The results of probiotic characteristic tests showed that MA2 could survive at pH 2.5 and 0.3% bile salt. Meanwhile, the measurements of cell surface hydrophobicity and autoaggregation were 45.29?±?2.15 and 6.30?±?0.34%, respectively. The results of cellular antioxidant activity tests indicated that MA2 had high antioxidant potential. The CAA value of logarithmic phase cell-free extract of MA2 (39,450.00?±?424.05 μmol quercetin equivalents/100 g sample) was significantly higher than that in stationary phase cell-free extract (3395.98?±?126.06 μmol quercetin equivalents/100 g sample) and that of fermentation supernatant in logarithmic phase (2174.41?±?224.47 μmol quercetin equivalents/100 g sample) (p?<?0.05). The CAA method was successively applied to evaluate the antioxidant capacity of MA2 in this study, which suggests that it could be used as a useful method for lactic acid bacteria antioxidant potential evaluation.     

Endocellulase Production by <Emphasis Type="Italic">Cotylidia pannosa</Emphasis> and its Application in Saccharification of Wheat Bran to Bioethanol

For efficient bioconversion of lignocellulosic materials to bioethanol, the study screened 19 white-rot fungal strains for their endocellulolytic activity and saccharification potential. Preliminary qualitative and quantitative screening revealed Cotylidia pannosa to be the most efficient endocellulase producing fungal strain when compared to the standard strain of Trichoderma reesei MTCC 164. Ensuing initial screening, the production of endocellulase was further optimized using submerged fermentation to recognize process parameters such as temperature, time, agitation pH, and supplementation of salts in media required for achieving maximum production of endocellulase. The strain C. pannosa produced the maximum amount of endocellulase (8.48 U/mL) under submerged fermentation with wheat bran (2%) supplemented yeast extract peptone dextrose (YEPD) medium after an incubation time of 56 h at 30 °C and pH 5.0 at an agitation rate of 120 rpm with a saccharification value of 50.5%. The fermentation of wheat bran hydrolysate with Saccharomyces cerevisiae MTCC 174 produced 4.12 g/L of bioethanol after 56 h of incubation at 30 °C. The results obtained from the present investigation establish the potential of white-rot fungus C. pannosa for hydrolysis and saccharification of wheat bran to yield fermentable sugars for their subsequent conversion to bioethanol, suggesting its application in efficient bioprocessing of lignocellulosic wastes.     

Multistrain probiotic production by co‐culture fermentation in a lab‐scale bioreactor

Most commercial probiotic products intended for pharmaceutical applications consist of combinations of probiotic strains and are available in various forms. The development of co‐culture fermentation conditions to produce probiotics with the correct proportion of viable microorganisms would reduce multiple operations and the associated costs. The aim of this study was to develop a fermentation medium and process to achieve biomass comprising the desired proportion of two probiotic strains in co‐culture. Initially, a quantification medium was developed, and the method was optimized to allow the quantification of each strain's biomass in a mixture. The specific growth rates of Lactobacillus delbrueckii spp. bulgaricus and Lactobacillus plantarum were determined in media with different carbon sources. The inoculum volume was optimized to achieve equal proportion of biomass in co‐culture fermentation in test tubes. Next, fermentation was carried out in a 3‐L bioreactor. A biomass concentration of 2.06 g/L, with L. delbrueckii spp. bulgaricus and L. plantarum in the ratio of 47%:53% (by weight), was achieved with concomitant production of 12.69 g/L of lactic acid in 14 h. The results show that with careful manipulation of process conditions, it is possible to achieve the desired proportion of individual strains in the final biomass produced by co‐culture fermentation. This process may serve as a model to produce multistrain probiotic drugs at industrial scale.     

Studies on a chlorogenic acid-producing endophytic fungi isolated from <Emphasis Type="Italic">Eucommia ulmoides</Emphasis> Oliver

Eucommia ulmoides Oliver is a traditional medicinal plant of China, and it is one of the main sources of chlorogenic acid. Chlorogenic acid is an ester of caffeic acid, quinic acid, and a phenolic compound that has antibacterial, antifungal, antioxidant, and antitumor activities. The purpose of this study was to determine whether endophytic fungi isolated from Eucommia ulmoides Oliver had the same ability to produce chlorogenic acid. Primary screening was done by antibacterial and antifungal reactions, and the strain reselection was done with high-performance liquid chromatography (HPLC) to identify the fermentation products of the selected strains. Extracts of the leaf and cortex of Eucommia ulmoides Oliver were also deteted by HPLC, then positive results of HPLC were analyzed by GC-MS and LC-MS. In this study, 29 strains were isolated from Eucommia ulmoides Oliver. Most of them had antibacterial activity, and a few of them had antifungal activity. One ingredient of the B5 extract had a retention time identical to that of authentic chlorogenic acid. With GC-MS, other ingredients, isocoumarin and p-chlorocinnamide, were found. With LC-MS, chlorogenic acid and geniposide related to Eucommia ulmoides Oliver were found. The strain B5 was identified as Sordariomycete sp. Thus, endophytic fungi may produce the bioactive compound chlorogenic acid, as their host plant does, and could be used for the production of chlorogenic acid by fermentation in the future.     

pH-, Lactic acid-, and non-lactic acid-dependent activities of probiotic Lactobacilli against Salmonella enterica Serovar Typhimurium

The mechanism(s) underlying the antibacterial activity of probiotic Lactobacillus strains appears to be multifactorial and includes lowering of the pH and the production of lactic acid and of antibacterial compounds, including bacteriocins and nonbacteriocin, non-lactic acid molecules. Addition of Dulbecco's modified Eagle's minimum essential medium to the incubating medium delays the killing activity of lactic acid. We found that the probiotic strains Lactobacillus johnsonii La1, Lactobacillus rhamnosus GG, Lactobacillus casei Shirota YIT9029, L. casei DN-114 001, and L. rhamnosus GR1 induced a dramatic decrease in the viability of Salmonella enterica serovar Typhimurium SL1344 mainly attributable to non-lactic acid molecule(s) present in the cell-free culture supernatant (CFCS). These molecules were more active against serovar Typhimurium SL1344 in the exponential growth phase than in the stationary growth phase. We also showed that the production of the non-lactic acid substance(s) responsible for the killing activity was dependent on growth temperature and that both unstable and stable substances with killing activity were present in the CFCSs. We found that the complete inhibition of serovar Typhimurium SL1344 growth results from a pH-lowering effect.     

Probiotic properties of Lactobacillus strains isolated from the feces of breast-fed infants and Taiwanese pickled cabbage

This study assessed potential probiotic Lactobacillus strains isolated from the feces of breast-fed infants and from Taiwanese pickled cabbage for their possible use in probiotic fermented foods by evaluating their (i) in vitro adhesive ability, resistance to biotic stress, resistance to pathogenic bacteria, and production of β-galactosidase; (ii) milk technological properties; and (iii) in vivo adhesive ability, intestinal survival and microbial changes during and after treatment. Five Lactobacillus isolates identified as Lactobacillus reuteri F03, Lactobacillus paracasei F08, Lactobacillus rhamnosus F14, Lactobacillus plantarum C06, and Lactobacillus acidophilus C11 that showed resistance to gastric juice and bile salts were selected for further evaluation of their probiotic properties. All the strains demonstrated the ability to adhere to Caco-2 cells, particularly, strain L. plantarum C06 and L. reuteri F03 showed satisfactory abilities, which were similar to that of the reference strain L. rhamnosus GG. The strains L. paracasei F08 and L. acidophilus C11 had the highest β-galactosidase activity. Most of the strains were resistant to aminoglycosides and vancomycin but sensitive to ampicillin, erythromycin, and penicillin. All the 5 strains elicited antibacterial activity against both Gram-positive (Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus) and -negative (Escherichia coli and Salmonella enterica) pathogens. Moreover, the strains L. reuteri F03, L. paracasei F08, and L. plantarum C06 could grow rapidly in milk without nutrient supplementation and reached 10? cfu/mL after 24 h of fermentation at 37 °C. The viable cell counts of the 3 strains remained above 10? cfu/mL after 21 d of storage at 4 °C. In the animal feeding trial, the number of intestinal lactobacilli increased significantly after administration of milk fermented with the 3 strains, and the counts of fecal coliforms and Clostridium perfringens were markedly reduced. Lactobacillus strains could also survive in the ileal intestinal tissue of the treated rats. Technologically interesting Lactobacillus isolates may be used in the future as probiotic starter cultures for manufacturing novel fermented foods.     

具有抗哈维氏弧菌活性共生真菌HLZ-3菌株的筛选、鉴定及其培养条件

【背景】目前,海水养殖业中主要利用抗生素来防治哈维氏弧菌等病原菌,但抗生素的长期使用或滥用会对环境和人体健康带来危害,因此既环保又有效的生物防治方法具有广阔的应用前景。【目的】从海水产品共生微生物中筛选具有抗菌活性的菌株,对活性菌株进行鉴定并确定其合成抗菌活性物质的培养条件。【方法】利用沙氏和2216E培养基,以稀释涂布平板法从海水养殖动物中分离真菌和细菌;利用牛津杯法测定微生物发酵液抗水产病原哈维氏弧菌的活性;通过菌株的培养特征、形态特征和ITS序列分析对抗菌活性菌株进行鉴定;通过筛选发酵培养基的种类及盐度确定培养条件。【结果】从海蚌、白虾、海蛎子等9种样品中分离出微生物52株,其中真菌30株、细菌22株;筛选得到2株具有抗哈维氏弧菌活性的真菌菌株;其中一株活性菌株HLZ-3被鉴定为塔宾曲霉;菌株HLZ-3合成抗菌活性物质的培养条件为4%NaCl的大米培养基,28°C静置培养2周。【结论】实验结果为进一步分离纯化菌株HLZ-3所产抗菌活性次生代谢产物提供了基础。     

Screening and Evaluation of Human Intestinal Lactobacilli for the Development of Novel Gastrointestinal Probiotics

The aim of this study was to screen intestinal lactobacilli strains for their advantageous properties to select those that could be used for the development of novel gastrointestinal probiotics. Ninety-three isolates were subjected to screening procedures. Fifty-nine percent of the examined lactobacilli showed the ability to auto-aggregate, 97% tolerated a high concentration of bile (2% w/v), 50% survived for 4 h at pH 3.0, and all strains were unaffected by a high concentration of pancreatin (0.5% w/v). One Lactobacillus buchneri strain was resistant to tetracycline. None of the tested strains caused lysis of human erythrocytes. Six potential probiotic strains were selected for safety evaluation in a mouse model. Five of 6 strains caused no translocation, and were considered safe. In conclusion, several strains belonging to different species and fermentation groups were found that have properties required for a potential probiotic strain. This study was the first phase of a multi-phase study aimed to develop a novel, safe and efficient prophylactic and therapeutic treatment system against gastrointestinal infections using genetically modified probiotic lactobacilli.     

Probiotic properties of Lactobacillus strains with high cinnamoyl esterase activity isolated from jeot-gal,a high-salt fermented seafood

Cinnamoyl esterases (CEs) improve the bioavailability of caffeic acid, a potent antioxidant with beneficial health effects. This study aimed to characterize the probiotic properties of 14 strains of CE-producing lactic acid bacteria (LAB) isolated from jeot-gal, a high-salt fermented seafood. We evaluated properties of the probiotic LAB with high CE activity, including tolerance to low pH and bile salts, antimicrobial activity, surface hydrophobicity, adhesion, and immunomodulatory effects, in vitro. All LAB tested tolerated pH 2.0 and 3% Oxgall, i.e., conditions comparable with those in the gastrointestinal environment. Three isolates, Lactobacillus paracasei JBCC10650, Lactobacillus pentosus JBCC10659, and Lactobacillus plantarum JBCC10543, showed stronger adherence to epithelial cells (12.3, 9.6, and 9.4%) than a commercial probiotic Lactobacillus rhamnosus GG (9.1%; p < 0.05), and exhibited broad antibacterial activity against putative pathogens. Most of the 14 LAB strains were able to regulate mRNA expression of pro- and anti-inflammatory cytokines in macrophages, indicating their potential immunomodulatory effects. Our findings suggest that the newly isolated CE-producing probiotics may show beneficial health effects by supporting the host immune system.     

pH-, Lactic Acid-, and Non-Lactic Acid-Dependent Activities of Probiotic Lactobacilli against Salmonella enterica Serovar Typhimurium

The mechanism(s) underlying the antibacterial activity of probiotic Lactobacillus strains appears to be multifactorial and includes lowering of the pH and the production of lactic acid and of antibacterial compounds, including bacteriocins and nonbacteriocin, non-lactic acid molecules. Addition of Dulbecco's modified Eagle's minimum essential medium to the incubating medium delays the killing activity of lactic acid. We found that the probiotic strains Lactobacillus johnsonii La1, Lactobacillus rhamnosus GG, Lactobacillus casei Shirota YIT9029, L. casei DN-114 001, and L. rhamnosus GR1 induced a dramatic decrease in the viability of Salmonella enterica serovar Typhimurium SL1344 mainly attributable to non-lactic acid molecule(s) present in the cell-free culture supernatant (CFCS). These molecules were more active against serovar Typhimurium SL1344 in the exponential growth phase than in the stationary growth phase. We also showed that the production of the non-lactic acid substance(s) responsible for the killing activity was dependent on growth temperature and that both unstable and stable substances with killing activity were present in the CFCSs. We found that the complete inhibition of serovar Typhimurium SL1344 growth results from a pH-lowering effect.     

红谷霉素对细菌抑制效果研究

红谷霉素是链霉菌702发酵后所产的一种生物活性物质,具有较强抗细菌活性。研究表明,红谷霉素对大肠杆菌的最低抑菌浓度为40mg/L,对枯草芽胞杆菌的最低抑菌浓度为0.08mg/L。红谷霉素在微生物生长迟滞期添加比在其它生长阶段添加抑菌效果更好,红谷霉素对热和紫外比较稳定。通过与其他防腐剂的抑菌效果比较表明,红谷霉素对细菌的抑菌效果优于比较的防腐剂。     

Enhancement of ribitol production during fermentation of <Emphasis Type="Italic">Trichosporonoides oedocephalis</Emphasis> ATCC 16958 by optimizing the medium and altering agitation strategies

To maximize the productivity of ribitol, which is an important starting material for the production of one expensive rare sugar, L-ribose, the effects of culture medium and agitation speed on cell growth as well as on the productivity of ribitol were thoroughly investigated in a 7 L fermentor. The maximum volumetric productivity, 0.322 g/L/h of ribitol, were obtained at an initial glucose concentration of 200 g/L in a batch culture. Based on the optimum glucose concentration, the ribitol yield conversed from glucose was up to 0.193 g/g when 1% yeast extract was used as a nitrogen source. When the agitation speed was maintained at 200 rpm, the ribitol concentration of 38.60 g/L was collected after 120 h of cultivation time. Additionally, the scheme of two-phase agitation and glucose infusion was employed. To begin, in the first 24 h of fermentation, a high agitation rate at 350 rpm and the initial glucose concentration of 50 g/L were applied, and the biomass concentration of 25.50 g/L was achieved at 36 h of incubation; whereas this value was observed until 60 h in the former batch fermentation methods. Then, in the second phase, with the agitation speed reduced to 150 rpm and the infusion amount of glucose controlled at 150 g/L, the yield of ribitol reached to 65.00 g/L in two-phase agitation fermentation and was 1.68 fold of that obtained in one-stage batch fermentation. To our knowledge, this study first demonstrates its significant effectiveness in improving ribitol production with the application of Trichosporonoides oedocephalis ATCC 16958.     

Optimization of submerged fermentation conditions for immunosuppressant mycophenolic acid production by Penicillium roqueforti isolated from blue-molded cheeses: enhanced production by ultraviolet and gamma irradiation

Mycophenolic acid (MPA) is a promising drug owing to its immunosuppressive and biological activities. In this study, two strains of Penicillium roqueforti designated as AG101 and LG109 were selected among several strains isolated from Roquefort cheese samples on the basis of their activity for MPA-producing ability. The appropriate fermentation conditions necessary for MPA biosynthesis by the two respective fungal strains were investigated. These conditions included selection of the cultivation medium, agitation rate, incubation temperature, fermentation time, pH value, inoculum size, and fermentation medium volume. Maximum MPA productivities were maintained when the fermentation process was carried out using a medium composed of (g l^?1): Sucrose, 30; peptone, 5.0; KH₂PO₄, 1.0; MgSO₄·7H₂O, 0.5 and KCl, 0.5; pH 6.0, inoculated with an inoculum size of 6.0 % (v/v), and incubated at 25 °C for 10 days at 120 rpm. The potentiality of both P. roqueforti strains for further improvement of MPA production was applied by mutagenesis through exposure to irradiation by ultraviolet rays (UV, 254 nm) for different periods of time and gamma rays at various doses (KGy). The dry cell weight of both irradiated fungal strains showed a greater reduction when irradiated either with UV or gamma rays. However, the MPA yield of both strains was increased by 1.27–1.39 fold when irradiated with UV rays and by 2.11–2.33 fold when irradiated with gamma rays, as compared with the respective controls (non-irradiated cultures). These findings indicate the future possibility to reduce the cost of producing fermentation-based drugs.     

Evaluation of the fermentability of oat fractions obtained by debranning using lactic acid bacteria

Aims: The overall kinetics of the fermentation of four oat fractions obtained by debranning using three potentially probiotic lactic acid bacteria were investigated. The main objective was to study the suitability of these fractions as fermentation media for the growth and the metabolic production of bacteria isolated from human intestine. Methods and Results: The cell growth, lactic acid production and substrate uptakes of the three lactobacilli was monitored for 30 h. An unstructured mathematical model was used to describe and fit the experimental data. In the medium from fraction B (1–3% pearlings or β-glucan-rich fraction) all strains reached the highest cell populations, maximum growth rates and maximum lactic acid productions. This could be because of the high levels of total fibre and β-glucan of this fraction. Limited growth and lactic acid formation was found in medium A (0–1% pearlings or bran-rich fraction). Conclusions: Medium B (1–3% pearling fraction) is the most suitable for fermentation and produces considerably higher probiotic cell concentrations. Significance and Impact of the Study: Debranning technology could be used to separate fractions from cereal grains for the production of functional formulations with higher probiotic levels than the ones that were obtained with the whole grain.