Increasing lipid production from Zygosaccharomyces siamensis AP1 in molasses substrate using sequencing batch method.

Yeasts are considered potential lipid producers to substitute oil-producing plants. Previous study succeeded in isolating Zygosaccharomyces siamensis AP1 from Indonesia which was able to accumulate 19% lipid. The strain, however, was not optimized for high cell density growth which is required for industry-level. In this study, efforts were made to increase cell density and lipid production of Z. siamensis AP1 using molasses as carbon source and implementing sequencing batch method. The yeast was grown in various combinations of carbon and nitrogen sources. The C:N ratio of the best substrate combination is then optimized. Afterwards, batch and sequencing batch methods were applied in fermentation with various concentrations (20-480 g/L) of molasses. The results show that lipid produced using molasses was slightly higher compared to using glucose, 0.21 g/L and 0.19 g/L respectively, with the same nitrogen source. Combination of molasses and ammonium sulfate with C:N ratio 70:1 gave the highest lipid (0.28 g/L). Sequencing batch able to increase cell density 2.4-fold compared to batch method. This study was the first to report that sequencing batch application with molasses as carbon source can increase lipid production from Z. siamensis. Further study to optimize medium composition for sequencing batch is suggested.

Genetic Diversity of Amylomyces rouxii from Ragi tapai in Java Island Based on Ribosomal Regions ITS1/ITS2 and D1/D2.

Amylomyces rouxii is commonly found as amylolytic fungi in tapai fermentation. However, its diversity is rarely reported despite being often used for food production in Southeast Asia. This research aims to analyze the genetic diversity and the distribution pattern of A. rouxii from Ragi tapai in Java Island, Indonesia. We isolated the fungus from samples obtained from Ragi tapai producing centers in Bandung, Sumedang, Muntilan, Blora, Yogyakarta, and Bondowoso. The obtained isolates were molecularly identified based on the ribosomal regions ITS1/ITS2 and D1/D2, then analyzed for phylogenetic tree reconstruction, genetic distance, genetic variation, and haplotype networking. Six isolates showed specific morphological traits of A. rouxii. However, phylogenetic tree reconstruction on the ribosomal genes showed that the isolates were grouped into two different clades related to two species. Clade A included BDG, SMD, and MTL isolates related to A. rouxii, whereas clade B included YOG, BLR, and BDS isolates related to Mucor indicus. The genetic distances between clades for ITS1/ITS2 and D1/D2 were 0.6145 and 0.1556, respectively. In conclusion, we confirmed the genetic diversity of molds from Ragi tapai in Java Island and showed that the isolates are not only related to A. rouxii as reported before.

Process Intensification of Enzymatic Fatty Acid Butyl Ester Synthesis Using a Continuous Centrifugal Contactor Separator.

Fatty acid butyl esters were synthesized from sunflower oil with 1-butanol using a homogeneous Rhizomucor miehei lipase in a biphasic organic (triglyceride, 1-butanol, hexane)- water (with enzyme) system in a continuous setup consisting of a cascade of a stirred tank reactor and a continuous centrifugal contactor separator (CCCS), the latter being used for integrated reaction and liquid-liquid separation. A fatty acid butyl ester yield up to 93% was obtained in the cascade when operated in a once-through mode. The cascade was run for 8 h without operational issues. Enzyme recycling was studied by reintroduction of the water phase from the CCCS outlet to the stirred tank reactor. Product yield decreased over time to an average of 50% of the initial value, likely due to accumulation of 1-butanol in water phase, loss of enzyme due to agglomeration, and the formation of a separate enzyme layer.