OPTIMIZATION OF SOLID-STATE FERMENTATION FOR PHYTASE PRODUCTION BY Thermomyces lanuginosus USING RESPONSE SURFACE METHODOLOGY

A strain of Thermomyces lanuginosus, isolated from hot spring water in Turkey, was studied for optimization of phytase production using solid-state fermentation. Effects on fermentation of different production parameters such as substrate type, moisture, culture time, and inoculum size were investigated using a one-factor-at-a-time approach. Central composite design (CCD) of response surface methodology was applied for the optimization of four factors (culture temperature, initial pH, aeration area, age of seeding culture) that were affecting phytase production by Thermomyces lanuginosus in rice bran. Maximum phytase activity was achieved by using rice bran. The optimum levels of variables that supported maximum enzyme activity were moisture 70%, culture time 7 days, inoculum size 40%, culture temperature 55 degrees C, initial pH 7.5, aeration area 30%, age of seeding culture 5 days, sucrose 1%, and ZnSO4 2.5mM. An overall 10.83-fold enhancement in phytase activity (0.30 to 3.248 U) was attained due to the optimization

Survival of Escherichia coli O157:H7 and Staphylococcus aureus during the fermentation and storage of kefir

Abstract The survival of Escherichia coli O157: H7 and Staphylococcus aureus, which are foodborne pathogens was investigated during fermentation and storage of kefir. The kefir grains were inoculated with 5% of the whole fat UHT cow milk and the E. coli O157: H7 and S. aureus cultures were added separately to give 105 cfu mL-1 and left to incubate at 22 °C for 24 hours at first stage. During the incubation, the bacteria and yeast counts, pH and titratable acidity amounts were determined. In the second stage, E. coli O157: H7 and S. aureus cultures were separately added to produce 105 cfu mL -1 of kefir and was stocked at 5 °C for 3 days. Every day samples were taken and the same tests were done. During fermentation, in all samples the initial while TA was 0.14%, the fermentation was 1.0% and 1.01% at the end. The kefir samples were pH 4.5 at the end of the 3 day period of storage. S.aureus was significantly inhibited while E.coli was not inhibited during the fermentation process. During storage, E. coli O157: H7 and S. aureus were inhibited within 2 days. The kefir has the quality of being a healthy product during fermentation and storage

MICROBIOLOGICAL INVESTIGATION OF BOTTLED MINERAL AND DRINKING WATERS SOLD IN ESKİŞEHİR (TURKEY) MARKETS

The microbiological quality of bottled natural spring and mineral water, purchased at different markets in Eskişehir (Turkey) markets, was investigated. Applying the membrane filtration method, the aliquots of water samples were analyzed for the presence and enumeration of total coliforms, Es- cherichia coli, Enterococcus spp., Aeromonas hydrophila. Aerobic bacteria were counted as Heterotrophic Bacteria Count (HPC) ml-¹ by incubation at 22 and 37 ⁰C. While Bacillus species in bottled mineral water samples have also been determined, any bacteria or contamination in bottled drinking water samples have not found

Improving lipid production capacity of new natural oleaginous yeast: Pichia cactophila firstly

Biodiesel is a useful alternative source of energy and can be used as a support for oil-source diesel. Microbial lipids are considered a promising raw material for biodiesel production. In a previously completed study, Pichia cactophila was found to be the best lipid-producing yeast by lipid screening studies among 107 yeast isolates. In this study, the lipid production conditions of P. cactophila, which was chosen as a lipid producer for the first time, were partially optimized by using response surface methodology in crude glycerol. Plackett-Burman statistical experiment design was used to determine the effect of glycerol, yeast extract, peptone, urea, (NH4)(2)SO4, NH4Cl, NH4NO3 factors on lipid production. In order to determine the optimum levels of the most effective parameters by the result of screening (glycerol, yeast extract, urea, NH4NO3), Box-Behnken experimental design method was used. The optimum production conditions were determined as 39 g/L glycerol, 20 g/L yeast extract, 5 g/L urea, and 20 g/L NH4NO3, and the result of the experiments carried out under these conditions the lipid value (%) was determined as 91.43. Lipid content was increased 1.408-fold (40.79%) by two-step optimization with the response surface methodology and reached a very high value. The fatty acid composition obtained under optimum conditions is compatible with vegetable oils. This suggests that the microbial lipid of P. cactophila can be used as a raw material for biodiesel production and is promising for further studies

Ethanol production from hazelnut shells through enzymatic saccharification and fermentation by low-temperature alkali pretreatment

Low-temperature sodium hydroxide (NaOH) pretreatment, enzymatic saccharification and ethanol fermentation were evaluated for hazelnut shell cellulose to fermentable sugars and ethanol. Maximum glucose recovery (48.33 g/100 g cellulose) was achieved with 6% NaOH for 72 h and at 1/10 solid/liquid ratio. At these conditions, 41.18% of lignin was removed. The theoretical ethanol yield (ethanol produced/potential glucose in biomass) was 40.71%, overall process efficiency was 37.73 g/kg biomass, ethanol productivity and fermentation efficiency were 0.115 g/(L h) and 96.7%, respectively. Total energy consumed for the low-temperature-long-residence-time alkali process was 34.8 Mj/kg untreated hazelnut shells. Pretreatment time has a significant effect on thermal energy consumption for the low-temperature alkali process. (C) 2017 Elsevier Ltd. All rights reserved