Rengin Eltem

Comparative Evaluation of Bio-Hydrogen Production From Cheese Whey Wastewater Under Thermophilic and Mesophilic Anaerobic Conditions

Hydrogen production from cheese whey wastewater via dark fermentation was conducted using mixed culture under mesophilic (36°C ± 1) and thermophilic (55°C ± 1) conditions, respectively. The hydrogen yields and specific hydrogen production rates were found as follows: mesophilic: 9.2 mmol H2 /g COD (chemical oxygen demand) and 5.1 mL H2 /g VSS h; thermophilic: 8.1 mmol H2 / g COD and 1.1 mL H2 /g VSS h. The reaction mixture for the mesophilic condition was composed of acetate (0.3–14.7%) and iso-butyrate (85–98%), plus other volatile fatty acids. On the other hand, the reactor mixture for the thermophilic condition was composed of acetate (1–43%) and iso-butyrate (29–46%).

Five-year survey of ochratoxin A in processed sultanas from Turkey

The results of surveillance for ochratoxin A (OTA) in 1885 samples of sultanas taken during five crop years between 1999 and 2003 are reported. The analytical method was based on extraction with methanol + sodium bicarbonate and clean-up by immunoaffinity column chromatography followed by high-performance liquid chromatography with fluorescence detection. The limit of detection for OTA was 0.3 µg kg−1. The results show that 9.3% of the samples contained no detectable levels of OTA, whereas 0.6% had concentrations exceeding 10 µg kg−1; the remaining 90.3% had levels within the range 0.3–10 µg kg−1. The overall mean OTA concentration in the total number of 1885 samples taken was 1.36 ± 2.91 µg kg−1; the overall median was calculated as 0.90 µg kg−1.

Ochratoxin A in sultanas from Turkey I : Survey of unprocessed sultanas from vineyards and packing-houses

A method for the determination of ochratoxin A (OTA) in sultanas from Turkey using extraction with a sodium bicarbonate solution (2% NaHCO3) followed by immunoaffinity clean-up and liquid chromatography with fluorescence detection was used to assess the frequency of occurrence and level of OTA. In-house validation was carried out with spiked samples at levels of 0.15, 1.5, 5.0 and 10 µg kg−1 and average recoveries were 91, 93, 87 and 89%, respectively. The limits of detection and limit of quantification in Turkish sultanas were 0.026 and 0.09 µg kg−1, respectively. A survey for the presence of OTA was carried out on 264 unprocessed sultana samples during the production seasons between 1998 and 2000 collected annually from vineyards and from packing-houses. The analyses of unprocessed sultanas showed that 32.2% of the total number of samples contained no detectable OTA, whereas 9.8% of sultana samples had OTA concentrations above 10 µg kg−1, and the remaining 58% had levels within the range 0.026–10 µg kg−1. There were big differences in median concentrations between years. Considering the year of production, it appears that sultanas produced in 1998 and 2000 showed the lowest incidence of OTA contamination (median < 0.02 µg kg−1), whereas 2002 showed the highest incidence (median = 4.3 µg kg−1). The overall mean OTA concentration was calculated as 3.4 µg kg−1, and the overall median as 0.9 µg kg−1. Among the samples analysed, the highest detected level of OTA was 54 µg kg−1.

Growth and aflatoxin B1 production on olives and olive paste by moulds isolated from ‘Turkish-style’ natural black olives in brine

The growth and aflatoxin production of five Aspergillus flavus and two Aspergillus parasiticus strains isolated from natural black olives in brine for table consumption, fresh whole black olives, fresh damaged black olives and fresh black olive paste were examined. Aspergillus flavus NRRL 6555 and A. parasiticus NRRL 2999 strains were also studied for comparison. All aflatoxigenic strains inoculated onto fresh damaged black olives and fresh black olive paste grew extensively but on fresh whole black olives they grew weakly. Strong aflatoxigenic strains produced low levels of aflatoxins on fresh whole black olives, fresh damaged black olives and fresh black olive paste. Weak aflatoxigenic strains did not produce detectable amounts of aflatoxin.

The Enhancement of Polygalacturonase and Polymethylgalacturonase Production on Solid-State Conditions by Aspergillus foetidus

In this study, a previously isolated strain of Aspergillus foetidu s Ege-K-635 producing highly active polygalacturonase and polymethylgalacturonase was used for improvement of enzyme production using solid-state conditions. To enhance the enzyme yield, the mixture of two substrates such as sugar beet pulp and wheat bran, having different ratios of carbon-nitrogen and moisture levels was used. Further the effect of the amount of inoculum was investigated. Physical parameters for the highest polygalacturonase and polymethylgalacturonase production under solid state conditions were determined on wheat bran: the sugar beet pulp (1:2) mixture substrate composition having a 31:1 carbon-nitrogen ratio with 8 × 106 spores/gram of dry substrate as the inoculum amount. Adequate moisture levels were 75% and 70% for polygalacturonase and polymethylgalacturonase, respectively. Under these conditions, the highest activities obtained were 385 ± 12.3 Ug−1 on the third day for polygalacturonase and 18.3 ± 3.2 Ug−1 on the second day for polymethylgalacturonase.

Chitooligosaccharides and their biological activities: A comprehensive review

Chitin is the most abundant natural polysaccharide and chitosan is its most important derivative. Regardless of having various bioactivities, the water insolubilities of chitin and chitosan limit their applications in many industries. The physical, chemical or enzymatic depolymerization of chitin and chitosan deliver chitooligosaccharides (COS): water-soluble and low molecular weight derivatives, superior to the parent polymers in multiple aspects. COS exhibit an enormously wide range of biological activities and a remarkable potential to be applied in various industries. This review has fully addressed the latest research on the biological activities of COS and the molecular mechanism behind these activities in a correlation with their physicochemical properties. Furthermore, an attempt has been made to report the commercially available COS products. The bioactivities discussed here may offer new understanding of the applications of COS in numerous sectors.

Some characteristics and isolation of novel thermostable β-galactosidase from Thermus oshimai DSM 12092

The β-galactosidases belong to the class of hydrolytic enzymes and have been used as lactose hyrolysis. The enzyme is used in reducing lactose milk production, an outstanding industrial product used by a large lactoseintolerant population. This is the first detailed report of some characteristics of β-galactosidase and the gene encoding β-galactosidase in Thermus oshimai DSM 12092. The growth rate (μ, 1/h), and the doubling time (tD, h) for T. oshimai grown both in shaking flasks and in a bioreactor were determined. The optimal temperature and pH for β-galactosidase were determined as 75°C and 7.4, respectively. This enzyme was thermostable and was retained by more than 70% at 90°C for 3 h. The β-galactosidase from T. oshimai DSM 12092 was more stable in basic pH and Zn2+ was the most effective divalent cation. Also, 2 steps of purification consisting of ammonium sulfate precipitation and gel filtration were employed and purified 32-fold.

Phosphate uptake performance of bacteria isolated from a full‐scale Izmir municipal wastewater treatment plant

This study investigated the phosphate uptake capacities of bacteria isolated from aerobic and anaerobic phosphate removal tanks at a municipal wastewater treatment plant in Izmir, Turkey, removing chemical oxygen demand to nitrogen (COD‐N) and phosphorus (P) on a full‐scale basis. Conventional plating techniques and an enrichment culture method were used to isolate the colonies, with a total of 91 monoculture isolates from the sludge samples being subjected to phosphate uptake studies. A total of 64 of these isolates had high phosphate uptake capacities ranging from 3.7 × 10−10 to 1.0 × 10−12 mg PO4 3− cell−1, and only 11 of the strains with high phosphate uptake were Gram‐negative. The highest phosphorus uptake value was 3.7 × 10−10 mg PO4 −3 cell−1, which was achieved by Gram‐positive bacteria. Gram‐negative strains were identified as Acinetobacter baumannii with a 99% probability and as Pseudomonas aeruginosa with a 96–98% probability (API 20 NE).

Effect of yearly conditions and management practices on ochratoxin A production in Sultana Seedless vineyards

Sun drying of seedless grapes (Vitis vinifera cv. Sultanina) is widely practised in the western Aegean Region providing Turkey with a significant share in the world trade of sultanas. Research was initiated in 1998 to determine the incidence of ochratoxin A (OTA), to identify the major factors resulting in contamination and to develop techniques to reduce or prevent contamination. This paper assesses OTA formation in five experimental vineyards located in Manisa province of Turkey between 1998 and 2003. The cultural practices recorded were tillage (type and timing), fertilisation, plant protection, irrigation, trellising, pruning, GA3 application, harvest maturity and date, and drying practices (type of drying yard, dipping into alkaline solution, length of drying period). In the experimental vineyards, no OTA was found at veraison. OTA levels in grapes harvested at fresh maturity ranged between <LOD and 8 ng g−1, whereas in dried sultanas they were between <LOD and 35 ng g−1. The frequency of OTA-positive samples increased in dried grapes compared with fresh. The number and timing of tillage, number of damaged berries, and removal of damaged/infected berries prior to sun drying were identified as the major good practices that may contribute to the reduction of OTA in sultanas.

Chitinolytic Bacillus subtilis Ege-B-1.19 as a biocontrol agent against mycotoxigenic and phytopathogenic fungi

Abstract Background Biological control of pathogenic fungi is a possible alternate to the chemical control, which is harmful to humans and environment. Soil-borne Bacillus strains can be potential biocontrol agents and a source of lytic enzymes. Aim This study aimed to examine biocontrol potential and lytic enzyme activities of a soil isolate Bacillus subtilis Ege-B-1.19. Materials and methods Strain was identified by biochemical and 16S rRNA gene analysis and its biocontrol activity was investigated against Aspergillus niger EGE-K-213, Aspergillus foetidus EGE-K-211, Aspergillus ochraceus EGE-K-217, Fusarium solani KCTC6328, Rhizoctonia solani KACC40111 and Colletotrichum gloeosporioides KACC40689. Chitinase, chitosanase, N-acetyl-β-hexosaminidase and protease activities of B. subtilis Ege-B-1.19 were also determined. Chitosanase was purified using Sephadex G-150 column and its molecular weight was determined by SDS-PAGE. Chitooligosaccharides production using chitosanase was carried out and analysed by TLC and HPLC. Results Results depicted that B. subtilis Ege-B-1.19 has shown inhibitory effects against all the test fungi. Chitinase, chitosanase, N-acetyl-β-hexosaminidase and protease activities were determined as 2.7 U mL−1, 7.2 U mL−1, 6.2 U mL−1 and 12.2 U mL−1, respectively. Molecular weight of purified chitosanase was 44 kDa. Chitosanase hydrolysed chitosan to glucosamine (GlcN), dimers (GlcN)2 and trimers (GlcN)3. Conclusion Bacillus subtilis Ege-B-1.19 can be anticipated as useful biocontrol agent and its chitosanase can be utilized for enzymatic synthesis of chitooligosaccharides.