Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2025A strategy for the one-pot direct production of 5-hydroxymethylfurfural (HMF) from sucrose using organic weak acid in situ as a catalyst
Gül, Abdulkadir; Tanyıldızı, Muhammet Şaban
5-Hydroxymethylfurfural (HMF), which can be produced in high yields by acid-catalyzed dehydration of carbohydrates, is used as a feedstock in biofuel and biopolymer production. However, these acidic catalysts are usually added externally, which increases HMF production costs. Furthermore, other important parameters for high yields of HMF production are raw material selection, reaction medium, and separation-purification processes. The aim of this study is to produce HMF in one-pot without the addition of any exogenous catalyst by evaluating the fructose remaining in the production medium in which the glucose from sucrose hydrolysis is microbially fermented into gluconic acid (GA). HMF production from fructose in a biphasic system consisting of a fermentation liquid containing GA and fructose and 2-Methyltetrahydrofuran (2-MeTHF) was optimized using Central Composite Design (CCD). The variables examined included reaction time, reaction temperature, solvent type, salt type, and organic/aqueous phase ratio. In the study, by chelating GA and calcium ions, the low degree of ionization of GA was increased, and HMF was produced in high yields without the addition of a catalyst. Under optimum conditions, using 2-MeTHF/ fermentation liquid (6:1) and 7.56 wt% CaCl2, the yield of HMF produced in pressurized (hydrothermal) vessels at about 147 °C for 158 min reached 77.6 % of the theoretical yield. The amount of GA in the production medium was 92.64 % preserved from degradation. GA and HMF in different phases of the biphasic system were purified from the production medium in high yields. Furthermore, 2-MeTHF, which constitutes the organic phase of the biphasic system, was recovered at approximately 95 % by vacuum evaporation. As a result, HMF production from sucrose, which is a more economical and abundant raw material compared to glucose and fructose, was realized in one-pot without the addition of any catalyst.
- MakaleAçık Erişim2024Sakkarozun Enzimatik Olarak Hidrolizinin Optimizasyonu
Gül, A.Kadir; Tanyıldızı, Muhammet Şaban
Nişasta kaynaklı glukoz şurupları endüstriyel uygulamalarda geniş bir paya sahip olmasına rağmen temelde sağlıkla ilgili tartışmalar tüketicilerde sakkarozun kullanımını öne çıkarmaktadır. Sakkaroz, asitleştirme veya enzimatik yöntemlerle invert şekerler adı verilen glukoz ve fruktoz monomerlerine hidroliz edilebilirler. Bu yöntemlerden enzimatik hidroliz işlemi geleneksel kimyasal proseslere göre daha düşük sıcaklıklarda gerçekleşmesi ve daha az toksik atık üretmesinden dolayı endüstride tercih edilen bir yöntemdir. Bununla birlikte, hidroliz işleminde kullanılan enzimler genellikle yeniden kullanımı zor ve stabilitesi düşük moleküller olup, üretim maliyetlerinin yüksek olması endüstriyel ölçekte uygulanmasını zorlaştırmaktadır. Bu çalışmanın amacı sakkarozun invertaz enzimi yardımıyla hidrolizinde önemli olan bağımsız değişkenlerin sakkaroz dönüşüm oranı, hidrolizi verimi ve toplam indirgen şeker konsantrasyonu üzerine etkisinin Merkez Kompozit Dizayn (MKD) deneysel tasarım yöntemi kullanılarak detaylı olarak belirlenmesidir. MKD ile gerçekleştirilen deneylerde incelenen bağımsız değişkenler ve cevap değişkenleri arasında enzim aktivitesini de içeren model bir denklem oluşturulmuştur. Bağımsız değişkenlerin incelenen aralıkları içerisinde, matematiksel model ifadenin hem indirgen şeker konsantrasyonu hem de dönüşümün maksimum olduğu şartlar için yapılan optimizasyon işlemi sonucunda; sakkaroz konsantrasyonu 190,16 g/L, enzim aktivitesi 55,36 U/mL, sıcaklık 33,46 oC, reaksiyon süresi 131,10 dk ve karıştırma hızı 120,86 rpm olarak belirlenmiştir. Sonuç olarak, sakkarozun enzimatik hidrolizi için verimli çalışma koşulları belirlenmiştir.
- MakaleAçık Erişim2024Gluconic Acid Production by Using Recombinant Escherichia coli Waksman pqq+ Cells with a Novel Approach from Biomass Sources
Gül, Abdulkadir; Tanyıldızı, Muhammet Şaban
Gluconic acid (GA) is widely used in the pharmaceutical, food, detergent, textile, leather, and concrete industries. However, cost-effective and high-yield production of GA remains a challenge. Due to currently high raw material inputs of GA, various alternative carbohydrate sources are being investigated. Sucrose is one of the cost-effective biomass sources that can be used as feedstock. The most common industrial production of GA is based on wild-type bacteria and fungi, but there are many problems with this production. This study aimed to optimize the production of GA from glucose produced by hydrolysis of sucrose using recombinant E. coli Waksman (W) pqq+ strain. After sucrose was enzymatically hydrolyzed, significant medium components for GA production were determined as glucose, calcium carbonate (CaCO3), peptone, and ammonium phosphate ((NH4)3PO4) using Placket-Burman Design (PBD). Detailed optimization of the medium components that are significant in GA production was carried out using central composite design (CCD), and optimum values of the independent variables examined in maximum GA production (93.5 ± 2.95 g/L) were determined as glucose 95, CaCO3 25, peptone 2, and (NH4)3PO4 1.13 (g/L). Using results obtained in the Erlenmeyer experiments, GA production in the bioreactor was investigated by CCD. The maximum GA efficiency (3.20 ± 0.15 g/L. h) was obtained under conditions where the air supply rate was 10.82 L/min, stirring speed was 656.87 rpm, and CaCO3 concentration was 16.90 g/L. In conclusion, it has been shown that GA can be produced with a high yield with this novel approach using a recombinant strain for GA production from sucrose.