Isolation and characterization of yogurt starter cultures from traditional yogurts and growth kinetics of selected cultures under lab-scale fermentation

The development of new starter cultures is a crucial task for the food industry to meet technological requirements and traditional products are important reservoirs for new starter cultures. In this respect, this study aimed to isolate, identify, and determine the technological characteristics of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains originated from traditional yogurt samples. Genotypic discrimination of 200 isolates revealed the presence of distinct 19 S. thermophilus and 11 Lb. delbrueckii subsp. bulgaricus strains as potential starter cultures. Strain-specific properties determined the acidification capacity of the yogurt starter cultures and a higher acidification capacity was observed for S. thermophilus strains compared to Lb. delbrueckii subsp. bulgaricus strains. Proteolytic activity was found between 0.012-0.172 and 0.078-0.406 for S. thermophilus and Lb. delbrueckii subsp. bulgaricus strains, respectively. 4 of S. thermophilus and 3 of Lb. delbrueckii subsp. bulgaricus strains were found resistant to all tested bacteriophages. The antibiotic susceptibility tests of the isolates revealed that a very low antibiotic resistance was observed for the yogurt starter cultures. Finally, the growth kinetics of selected strains were determined and the maximum specific growth rate of selected S. thermophilus and Lb. delbrueckii subsp. bulgaricus was calculated as 0.527 h^-1 and 0.589 h^-1, respectively.

Removal of ethanethiol using a biotrickling filter with nitrate as an electron acceptor

Many studies have discussed the biotreatment of ethanethiol (ET) under aerobic conditions. However, O₂ free conditions offer bio-conversion of ET gas into elemental sulphur and/or sulphate using [Formula: see text] as electron acceptor, and this has been not studied. In this study, an anoxic biotrickling filter was tested in lab-scale conditions with ET/[Formula: see text] ratio 0.74 and 0.34 mole/mole to remove malodorous ET waste gas. The study examined the effect of three operational parameters: ET inlet concentrations (150, 300, 800, and 1500 mg/m³), trickling velocities (0.12, 0.18, 0.24, 0.3, and 0.45 m/h), and empty bed residence times (30, 60, 90, and 120 s). It found that the effect of trickling velocity on removal efficiency depended on inlet concentrations; 0.24 m/h trickling velocity resulted in efficient ET removal (higher than 90.8% for 150 mg/m³ of inlet concentration) while 0.45 m/h trickling velocity could only achieve a removal of 80.6% for 1500 mg/m³ of inlet concentration at fixed EBRT 60 s. Increasing the EBRT up to 60 s was adequate to achieve removal efficiency, i.e. 92 and 80% for ET inlet concentrations 150 and 1500 mg/m³ respectively, and the maximum elimination capacity was 75.18 g/m³/h at 0.45 m/h. Overall, the anoxic conditions enhanced the low oxidation rates of ET in an anoxic biotrickling filter despite mass transfer limitations and poor solubility of ET.

Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger

BACKGROUND

Bio-based production of organic acids promises to be an attractive alternative for the chemicals industry to substitute petrochemicals as building-block chemicals. In recent years, itaconic acid (IA, methylenesuccinic acid) has been established as a sustainable building-block chemical for the manufacture of various products such as synthetic resins, coatings, and biofuels. The natural IA producer Aspergillus terreus is currently used for industrial IA production; however, the filamentous fungus Aspergillus niger has been suggested to be a more suitable host for this purpose. In our previous report, we communicated the overexpression of a putative cytosolic citrate synthase citB in an A. niger strain carrying the full IA biosynthesis gene cluster from A. terreus, which resulted in the highest final titer reported for A. niger (26.2 g/L IA). In this research, we have attempted to improve this pathway by increasing the cytosolic acetyl-CoA pool. Additionally, we have also performed fermentation optimization by varying the nitrogen source and concentration.

RESULTS

To increase the cytosolic acetyl-CoA pool, we have overexpressed genes acl1 and acl2 that together encode for ATP-citrate lyase (ACL). Metabolic engineering of ACL resulted in improved IA production through an apparent increase in glycolytic flux. Strains that overexpress acl12 show an increased yield, titer and productivity in comparison with parental strain CitB#99. Furthermore, IA fermentation conditions were improved by nitrogen supplementation, which resulted in alkalization of the medium and thereby reducing IA-induced weak-acid stress. In turn, the alkalizing effect of nitrogen supplementation enabled an elongated idiophase and allowed final titers up to 42.7 g/L to be reached at a productivity of 0.18 g/L/h and yield of 0.26 g/g in 10-L bioreactors.

CONCLUSION

Ultimately, this study shows that metabolic engineering of ACL in our rewired IA biosynthesis pathway leads to improved IA production in A. niger due to an increase in glycolytic flux. Furthermore, IA fermentation conditions were improved by nitrogen supplementation that alleviates IA induced weak-acid stress and extends the idiophase.

Comparison of different estimation techniques for biomass concentration in large scale yeast fermentation

In this study, previously developed five different state estimation methods are examined and compared for estimation of biomass concentrations at a production scale fed-batch bioprocess. These methods are i. estimation based on kinetic model of overflow metabolism; ii. estimation based on metabolic black-box model; iii. estimation based on observer; iv. estimation based on artificial neural network; v. estimation based on differential evaluation. Biomass concentrations are estimated from available measurements and compared with experimental data obtained from large scale fermentations. The advantages and disadvantages of the presented techniques are discussed with regard to accuracy, reproducibility, number of primary measurements required and adaptation to different working conditions. Among the various techniques, the metabolic black-box method seems to have advantages although the number of measurements required is more than that for the other methods. However, the required extra measurements are based on commonly employed instruments in an industrial environment. This method is used for developing a model based control of fed-batch yeast fermentations.

On-line evolutionary optimization of an industrial fed-batch yeast fermentation process

This paper presents two genetic algorithms based on optimization methods to maximize biomass concentration, and to minimize ethanol formation. The objective function is maximized according to the values of feed flow rate, using genetic search approaches. Five case studies were carried out for different initial conditions, which strongly influence the optimal profiles of feed flow rate for the fermentation process. The ethanol and glucose disturbance effects were examined to stress the effectiveness of proposed approaches. The proposed genetic approaches were implemented for an industrial scale baker's yeast fermentor which produces Saccharomyces cerevisiae known as baker's yeast. The results show that optimal feed flow rate was obtained in a satisfactory and successful way for fed-batch fermentation process.

Removal of ammonia as struvite from anaerobic digester effluents and recycling of magnesium and phosphate

A second order kinetic model was developed to predict the rate and extent of NH(4)(+) removal as struvite from anaerobic digester effluents. Alternative to this, NH(4)(+) can be recovered from struvite and the remaining Mg(2+) and PO(4)(3-) can be recycled back to the wastewater to fix more NH(4)(+). The NH(4)(+) solution was retained and the remaining Mg(2+) and PO(4)(3-) were returned back to be mixed with wastewater. In a five-step process, NH(4)(+) recovery was initially 92% and progressively decreased to 77% in the fifth stage, due to loss of Mg(2+) and PO(4)(3-) at each step in the supernatant. Finally, economic analysis of recycling nutrients was performed and compared to the one step process. The cost of NH(4)(+) recovery was calculated as $0.36/kgNH(4)-N which is lower than $7.7/kgNH(4)-N the cost of one step process without considering the market value of struvite obtained in one step process.

Recovery of ammonia as struvite from anaerobic digester effluents

The effects of environmental conditions on ammonia removal as struvite (Magnesium ammonium phosphate, MAP) were studied in a laboratory scale batch reactor. MAP precipitation was carried out by adding phosphoric acid and magnesium source either as MgCl, or MgO. The effect of temperature, pH, MgN:P ratios were studied. Temperature did not significantly affect ammonia removal between 25-40 degrees C and over 90% removal was obtained. The effect of pH, however,was significant and highest removal was reached at pH 8.5-9.0. The various stoichiometric ratios of ammonium to Mg and P have been tested and slight excess of Mg and P found to be beneficial for higher recovery of ammonia as struvite. However further increase in Mg and P ratios did not result in further ammonia removal which is also costly for the practical application of the process. When MgO was used as M source,the ammonia recovery was 60-70% whereas the useMgCl2 has increased this figure up to 95%. In addition a two step purification process was developed to recover MAP crystals from impurities of the anaerobic digester. Firstly, precipitates were dissolved in acid and impurities were removed by centrifugation. The clarified supernatant was re-precipitated by adjusting its pH with caustic. It was shown that in the two steps process white MAP crystals could be obtained with over 85% recovery to be used for another applications. The economical analysis of the process has shown that ammonia in the digester effluents can be recovered at the cost of $7.5-8.0 kg(-1) NH4+-N. The rate of reaction is very fast and is completed almost in minutes. This simplifies the process design resulting in a smaller reaction vessel.

Oral cyclic megadose methylprednisolone therapy for chronic immune thrombocytopenic purpura in childhood

The objectives of this study were to investigate the effectiveness of oral megadose methylprednisolone (OMMP) therapy in children with chronic immune thrombocytopenic purpura (ITP). Twenty-two patients were given oral methylprednisolone daily for 7 d (30 mg/kg for 3 d and then 20 mg/kg for 4 d). OMMP therapy was repeated once per month if the platelet count was less than 20,000/mm3 at the 30th day of therapy, for up to six courses. The number of platelets of all patients increased gradually during the OMMP therapy, with a peak number at the 7th day, then decreased until the 14th day, and remained relatively stable until 12 months. During the study no patient had a platelet count less than 20,000/mm3 at the 3rd day and 50,000/mm3 at the 7th day. Although the number of platelets was gradually decreased between the 7th and 14th days, it remained above 100,000/mm3 for at least 12 months in the nine patients, and above 20,000/mm3 in the four patients. None of these 13 patients required hospitalization or therapy during the follow-up period. All of the patients tolerated the medication well. None of them reported side-effects that were severe enough to discontinue therapy. We conclude that OMMP therapy is a safe, easy and effective therapy in children with refractory chronic ITP, and it may provide long-term remission in about two thirds of the patients.

The effect of propolis extract in experimental chemical corneal injury

PURPOSE

To investigate the effect of propolis, a natural resin produced by honeybees, in the treatment of alkali-injured rabbit eyes.

METHOD

A corneal alkali burn was induced by applying filter paper immersed in 1 N NaOH on the central axis of the right corneas of 24 rabbits for 30 s. The animals were divided into three treatment groups: group 1 (control) was given 0.3% tobramycin and phosphate-buffered solution; group 2 was treated with antibiotic coverage and topical 1% ethanolic extract of propolis; group 3 received antibiotic coverage and topical 1% dexamethasone. The dexamethasone-treated group was maintained as the positive control. Drugs were instilled 4 times a day for 7 days. The corneal inflammation was evaluated by calculating the average inflammatory index obtained from clinical observation of the ciliary hyperemia, central and peripheral corneal edema at 24 h, 48 h, on day 5 and day 7, before sacrificing the animals. Then, the corneas underwent routine histological examination.

RESULTS

The effects of dexamethasone and propolis on healing of injured corneas were similar (p>0.05) and significantly better than controls at 24 h (p<0.01, p< 0.05, respectively), and on day 7 (p<0.05) with respect to the inflammatory index. On histological observation, inflammatory cell infiltration was lower as compared to control in both the dexamethasone and propolis groups (p<0.001) and similar with each other (p>0.05).

CONCLUSIONS

Our study shows that propolis has an anti-inflammatory effect comparable to dexamethasone in chemical corneal injury.

Cyclosporin A plus prednisone treatment of steroid-sensitive frequently relapsing nephrotic syndrome in children

Recently, there have been numerous reports on the use of cyclosporin A (CyA) in children with nephrotic syndrome (NS). In this prospective study, we wanted to evaluate the efficacy of CyA together with prednisone therapy in children with steroid-sensitive frequently relapsing NS. A total of 11 children (7 boys, 4 girls) with steroid-sensitive NS were included in this study. The patients ranged in age from 3.5 to 15 years (average 8.45 +/- 4.26 years). Renal biopsy showed minimal change disease in five, mesangial proliferation in four, focal glomerulosclerosis in one and membranous glomerulonephritis in one. The NS had lasted from 13 to 113 months (average 50.27 +/- 38.60 months). The number of relapses varied from three to 10 episodes with an average of 5.9 +/- 3.3 episodes. Patients received 5 mg/kg CyA daily in two divided doses for five months and prednisone for a total of eight weeks (30 mg/m2 daily for 4 weeks followed by 30 mg/m2 on alternate days for 4 weeks). After the completion of the treatment protocol, no therapy was given unless a relapse was observed. Mean follow-up period was 14.9 +/- 5.99 months with a range from six to 26 months. Before this combined treatment, there was a mean relapse rate of 0.144 +/- 0.05 relapses month with a range from 0.088 to 0.238. After discontinuation of therapy, the relapse rate dropped to a mean of 0.0179 +/- 0.031 with a range of 0 to 0.083. In conclusion, it would appear that a combination of CyA and prednisone is effective, sustaining the remission in steroid-sensitive NS. Corticosteroids in combination with CyA may be a better approach than conventional steroid treatment in such patients.

Left ventricular diastolic abnormalities in children with beta-thalassemia major: a Doppler echocardiographic study

Left ventricular filling patterns were assessed by Doppler echocardiography in 63 beta-thalassemia major patients, aged for to 21 years, with no clinical evidence of congestive heart failure and 63 age- and sex-matched normal controls. The patients with beta-thalassemia major were divided into three age groups, namely four to nine years (6.8 +/- 1.5 years), 10-15 years (12.1 +/- 1.6 years) and older than 15 years (17.3 +/- 1.7 years). They were compared with age- and sex-matched normal controls in respects of Doppler diastolic indices. The ratio between the early and late (atrial) peaks of flow velocity was higher and peak flow velocity in late diastole was significantly lower in patients with beta-thalassemia major as compared to controls in all three age groups (p < .001). As compared with the controls, peak early diastolic flow velocity was also significantly higher in the thalassemics aged 10 to 15 years (92 +/- 16 vs 80 +/- 12 cm/s, P < .01) and in those older than 15 years (95 +/- 16 vs 79 +/- 13 cm/s, p < .001). Restrictive left ventricular diastolic abnormalities were detected in a total of 34 (54%) patients with beta-thalassemia major, whereas left ventricular systolic abnormalities were identified only eight (13%) of them. None of the patients without left ventricular diastolic abnormalities showed left ventricular systolic abnormalities. There was not any significant correlation between the hematologic parameters, such as mean serum ferritin, maximum serum ferritin and the number of blood units transfused, and left ventricular Doppler diastolic indices (p > .05). From the data presented here, we therefore conclude that left ventricular diastolic abnormalities develop in patients with beta-thalassemia major in the early phase of the disease and before the appearance of systolic abnormalities, when clinical symptoms of congestive heart failure are absent.

A comparison of different filters for white cell reduction

Removal of white blood cells (WBCs) from blood components before transfusion by filters with at least 3 log10 depletion may prevent or delay leukocyte-associated transfusion reactions such as HLA alloimmunization, non-hemolytic febrile reactions, transmitted infections (e.g., CMV, HTLV-1), and immunomodulation. The aim of this study was to compare the leukocyte removal efficiency (LRE) of six commercial bedside filters that are said to achieve 3 log10 (Bio R-01), Leucostop 4LT-1, Pall RC 50) and 4 log10 (Bio R-01 Plus, Pall RC 400, Pall RC XL-1) WBC depletion. A total of 430 units of whole blood ranging from 32 to 92 for each filter type were analyzed by an automated counter before and after filtration. Postfiltration blood samples were also evaluated for WBCs by Nageotte chamber. All the filters demonstrated leukocyte removal about 1 log10 less than the manufacturer's claim. The fourth generation filters showed a better performance than the third generation filters. Of them, Pall RC XL-1 showed the best efficacy with 99.93 percent leukocyte removal and a median residual WBCs of 1.6 x 10(6) per unit. These results indicate that the fourth generation filters, which are designed for the filtration of packed red cells, in particular Pall RC XL-1, are also able to reduce WBCs from whole blood below the critical antigenic leukocyte load (5 x 10(6)), and can be efficiently used for polytransfused patients to prevent alloimmunization.

Experimental investigation of bone regeneration using Pyrost in animals

A study was undertaken to investigate bone regeneration in guinea pig mandibles implanted with Pyrost in comparison with artificial bone defects as controls. Bone defects were prepared in the angles of mandibles of 30 guinea pigs. The findings demonstrated that this bone substitute material stimulated bone healing, i.e. bone regeneration, in comparison with empty control cavities. Bone regeneration and new bone formation were found to be more extensive in Pyrost-implanted areas than in controls.

Early pulpal involvement in an unusual case of dens in dente. Case report

Dens in dente (dens invaginatus, tooth within a tooth, dilated composite odontome) is an abnormal tooth form which occurs most frequently in the permanent maxillary lateral incisor region. Dens in dente may occur, however, in any tooth in the dental arch, although these other forms are comparatively rare. It may appear within both the coronal part of the tooth and the root, although coronal forms are more common. In this paper, a case of extreme dens in dente with pulpal involvement at an early stage of eruption is presented.

A new surgical approach in genital lymphedema

A new surgical approach has been used in a case of genital lymphedema. After resection of the lymphedematous mass, U-shaped flaps were made from the suprapubic region anteriorly and the posterior scrotal skin posteriorly. The denuded penis was transposed to its original place by passing it through a buttonhole incision made on the anterior flap. The testicles were placed and fixed in pouches prepared between the anterior and posterior flaps. The patient had an acceptable postoperative outcome both in testicular function and habitual sexual activities.

[Role of odontomas on eruption difficulties of permanent teeth and surgical-orthodontical approach]

In this case report 2 odontoma cases were presented as an example for surgical-orthodontic approach for the eruption difficulties of permanent teeth. In two cases which left central incisors couldn't erupt because of an odontoma. In both cases the odontomas were enucleated with their capsules and treated orthodontically thus the results were discussed.