Ramlan Aziz

Recent advances in production of succinic acid from lignocellulosic biomass

Production of succinic acid via separate enzymatic hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) are alternatives and are environmentally friendly processes. These processes have attained considerable positions in the industry with their own share of challenges and problems. The high-value succinic acid is extensively used in chemical, food, pharmaceutical, leather and textile industries and can be efficiently produced via several methods. Previously, succinic acid production via chemical synthesis from petrochemical or refined sugar has been the focus of interest of most reviewers. However, these expensive substrates have been recently replaced by alternative sustainable raw materials such as lignocellulosic biomass, which is cheap and abundantly available. Thus, this review focuses on succinic acid production utilizing lignocellulosic material as a potential substrate for SSF and SHF. SSF is an economical single-step process which can be a substitute for SHF — a two-step process where biomass is hydrolyzed in the first step and fermented in the second step. SSF of lignocellulosic biomass under optimum temperature and pH conditions results in the controlled release of sugar and simultaneous conversion into succinic acid by specific microorganisms, reducing reaction time and costs and increasing productivity. In addition, main process parameters which influence SHF and SSF processes such as batch and fed-batch fermentation conditions using different microbial strains are discussed in detail.

The Mechanisms of Inhibition of Advanced Glycation End Products Formation through Polyphenols in Hyperglycemic Condition.

Glycation, the non-enzymatic binding of glucose to free amino groups of an amino acid, yields irreversible heterogeneous compounds known as advanced glycation end products. Those products play a significant role in diabetic complications. In the present article we briefly discuss the contribution of advanced glycation end products to the pathogenesis of diabetic complications, such as atherosclerosis, diabetic retinopathy, nephropathy, neuropathy, and wound healing. Then we mention the various mechanisms by which polyphenols inhibit the formation of advanced glycation end products. Finally, recent supporting documents are presented to clarify the inhibitory effects of polyphenols on the formation of advanced glycation end products. Phytochemicals apply several antiglycation mechanisms, including glucose metabolism, amelioration of oxidative stress, scavenging of dicarbonyl species, and up/down-regulation of gene expression. To utilize polyphenols in order to remedy diabetic complications, we must explore, examine and clarify the action mechanisms of the components of polyphenols.

Bioprocess Development for High Cell Mass Production of the Probiotic Yeast-Kluyveromyces lactis

In the present study, the key industrial strain of Kluyveromyces lactis NRRL Y-110 was used to develop an industrial process for probiotic cell mass production. Therefore, the biomass production process of K. lactis was developed via the optimization of different medium and process parameters in shake flask and bioreactor levels. In the first part of the work, the effect of medium composition on the production of biomass was investigated in shake flask culture. Among different production media studied, the medium composed of lactose, ammonium sulphate, magnesium sulphate, potassium dihydrogen phosphate and yeast extract yielded the highest volumetric high cell mass production of 4.34 g.L -1 after 24 hours cultivation. Furthermore, the optimization involved different key nutrients (carbon sources, nitrogen sources and mineral sources). The results obtained are helpful for the overproduction of highest cell mass by submerged culture of K. lactis on a semi-industrial scale. During bioreactor cultivation under controlled and uncontrolled pH, results showed that, high cell biomass yield of 15.1 g.L -1 was produced under controlled pH conditions compared to uncontrolled pH. This value was almost 48.30% higher than those obtained in controlled pH submerged shake flask culture.