Murat Ozdal

Asymmetric reduction of substituted acetophenones using once immobilized Rhodotorula glutinis cells

The asymmetric reductions of acetophenone and its analogues using once immobilized Rhodotorula glutinis cells were studied. The performance and reaction parameters of the immobilized cells were also investigated and it was determined that the cells could be used 15 times in batch processes. All chiral alcohols obtained using purification procedures were of sufficient enantiopurity (>99%) of the (S)-enantiomer. The applicability of the optimized process for a preparative scale bioreduction was shown. Under the optimum conditions, 35mM (4.3g) of the product ((S)-1-phenylethanol) was produced from 45mM (5.4g) of the substrate (acetophenone) with one time immobilized R. glutinis EBK-2 cells (6g wet weight). The yield was calculated as 77%. In this study, it was found that the buffer level had a very significant effect on the reaction activity. Our results demonstrate that the optimized process can be implemented on a preparative scale.

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.

Single-cell protein as an alternative food for zebrafish, Danio rerio: a toxicological assessment

Single-cell protein (SCP) refers to the dried cells of microorganisms. The aim of this research was to evaluate the nutrional characteristics and possible toxic effects of the SCP of Trichoderma harzianum. First, T. harzianum was grown on whey filtrate agar medium and the obtained SCP was analysed. It was rich in both total protein (34.21%) and ash (4.78%). Furthermore, the biomass contained all the essential amino acids, and the amino acid concentrations were very close to the FAO reference protein levels. Second, we exposed zebrafish (Danio rerio) embryos to diluted SCP at various concentrations for 96 hours postfertilization (hpf). Compared with the control group, we did not observe any developmental abnormalities, delayed hatching, and lethal effects on zebrafish embryos (96 hpf) found in the SCP group. To test diet effects on spawning success and growth of embryos, adult zebrafish were fed on SCP and flake feed diets for 10 weeks. The number of laid eggs, wet weight and diameter of eggs, and the percentages of hatched eggs from fish fed the flake diet and SCP diet were not significantly different from each other. Also, larval length and weight were not significantly affected by diets. Finally, SCP did not cause any toxic effect on zebrafish adults and their offsprings and could be useful as fish food or food additive.

Statistical optimization of beta-carotene production by Arthrobacter agilis A17 using response surface methodology and Box-Behnken design

β-carotene is a commercially important natural pigment and has been widely applied in the medicine, pharmaceutical, food, feed and cosmetic industries. The current study aimed to investigate the usability of molasses for β-carotene production by Arthrobacter agilis A17 (KP318146) and to optimize the production process. Box-Behnken Design of Response Surface Methodology was used to determine the optimum levels and the interactions of three independent variables namely molasses, yeast extract and KH2PO4 at three different levels. β-carotene yield in optimized medium containing 70 g/l molasses, 25 g/l yeast extract and 0.96 g/l KH2PO4, reached up to 100 mg/l, which is approximately 2.5-fold higher than the yield, obtained from control cultivation. A remarkable β-carotene production on inexpensive carbon source was achieved with the use of statistical optimization.

Rhamnolipid production by Pseudomonas aeruginosa OG1 using waste frying oil and ram horn peptone

Agro-industrial by-products are being explored as alternative low-cost nutrients for various bioprocesses. In this work, the applicability of ram horn peptone (RHP) and waste frying oil were investigated for rhamnolipid production by Pseudomonas aeruginosa as the sole nitrogen and carbon sources, respectively. The rhamnolipid yield was considerably influenced by the type of organic nitrogen source. Among the tested organic nitrogen sources, RHP proved to be the best nitrogen source for both biomass and rhamnolipid production. RHP was also tested at different concentrations and 10 g/L RHP resulted in the greatest yield of rhamnolipid (12.1 g/L) in the presence of waste frying oil as the sole carbon source. These results revealed that rhamnolipid could be produced efficiently and cost effectively by P. aeruginosa OG1 using RHP and waste frying oil.Agro-industrial by-products are being explored as alternative low-cost nutrients for various bioprocesses. In this work, the applicability of ram horn peptone (RHP) and waste frying oil were investigated for rhamnolipid production by Pseudomonas aeruginosa as the sole nitrogen and carbon sources, respectively. The rhamnolipid yield was considerably influenced by the type of organic nitrogen source. Among the tested organic nitrogen sources, RHP proved to be the best nitrogen source for both biomass and rhamnolipid production. RHP was also tested at different concentrations and 10 g/L RHP resulted in the greatest yield of rhamnolipid (12.1 g/L) in the presence of waste frying oil as the sole carbon source. These results revealed that rhamnolipid could be produced efficiently and cost effectively by P. aeruginosa OG1 using RHP and waste frying oil.

Valorisation of chicken feathers for xanthan gum production using Xanthomonas campestris MO-03

Xanthan gum is an important commercial polysaccharide produced by Xanthomonas species. In this study, xanthan production was investigated using a local isolate of Xanthomonas campestris MO-03 in medium containing various concentrations of chicken feather peptone (CFP) as an enhancer substrate. CFP was produced with a chemical process and its chemical composition was determined. The addition of CFP (1–8 g/l) increased the conversion of sugar to xanthan gum in comparison with the control medium, which did not contain additional supplements. The highest xanthan production (24.45 g/l) was found at the 6 g/l CFP containing control medium in 54 h. This value was 1.73 fold higher than that of control medium (14.12 g/l). Moreover, addition of CFP improved the composition of xanthan gum; the pyruvate content of xanthan was 3.86% (w/w), higher than that of the control (2.2%, w/w). The xanthan gum yield was also influenced by the type of organic nitrogen sources. As a conclusion, CFP was found to be a suitable substrate for xanthan gum production.