Isolation, molecular identification of lipid-producing Rhodotorula diobovata: optimization of lipid accumulation for biodiesel production

Abstract

Background The increased demand for oil and fats to satisfy the ever-increasing human needs has enhanced the research in this field. Single-cell oils or microbial lipids produced by oleaginous microorganisms are being utilized as an alternative to traditional oil sources. Oleaginous yeasts can accumulate lipids above 20% of their biomass when they are grown under controlled conditions. Results In the present study, sixty-five yeasts were isolated from different sources. Using Sudan Black B staining technique, five yeast isolates were selected. Under nitrogen-limited cultivation conditions, the Co1 isolate was the best lipid accumulation potential of 39.79%. Isolate (Co1) was characterized morphologically and identified using the ribosomal DNA internal transcribed spacers regions (rDNA-ITS) from their genomic DNA. The sequence alignment revealed a 99.2% similarity with Rhodotorula diobovata. Under the optimized conditions, Rhodotorula diobovata accumulated lipids up to 45.85% on a dry biomass basis. R. diobovata, when grown on different raw materials, accumulated lipid up to 46.68% on sugar beet molasses medium, and the lipid had a high degree of monounsaturated fatty acids which gives biodiesel better quality. Conclusions The data suggest that the potent oleaginous yeast, R. diobovata, together with the use of cheap feedstock raw materials such as sugar beet molasses, can be considered as a promising feedstock for biodiesel production.

Screening of biohydrogen producing endophytic fungi from biodiesel plants

“…The fungi stained with Sudan Black B revealed observations which were similar to earlier reports. [ 33 ] The microscopic observations on staining revealed that the change in color indicated a change in the character of the lipids in terms of fatty acid composition, extent of saturation, leading to progressive lipid accumulation in the fungal isolates. This staining intensity revealed lipid producing isolates, which were further studied for lipid quantification.…”

Isolation, characterization and optimization of Cystobasidium minutum for phytase production

“…By using BLAST (http://www.ncbi.nlm.nih.gov/BLAST/), the resulting sequences were compared to rDNA sequences from the GenBank. Clustal W (http://www.ebi.ac.uk/Tools/clustalw2/index.html) was used to align the ITS segments received from the GenBank database and MEGA 11 was used to create the phylogenetic tree using the neighbour-joining method (20,21).…”

Exploring Yeast Diversity to Produce Lipid-Based Biofuels from Agro-Forestry and Industrial Organic Residues

“…The size and physiological state of the inoculum are critical to the performance of stress-associated bioprocess, as is the case for most of the bioconversions of lignocellulosic biomass and other organic residues/wastes by yeasts. Additionally, the inoculum size influences biomass production, lipid titer and lipid content [ 202 , 203 , 204 , 205 ]. It is expected that an increase in the inoculum size (frequently associated with the initial culture OD 600nm ) may lead to the increase in the concentration of viable producing cells capable of initiating growth under stress conditions, in particular under the toxic effect of chemicals present in lignocellulosic biomass hydrolysates or in any other organic residues [ 65 ].…”

“…A similar increase in process performance concerning the consumption rate of a mixture of xylose and glucose was reported for L. starkeyi when the inoculum size was increased [ 202 ]. An inoculum ratio of 10% ( v / v ) was considered ideal for maximum biomass and lipid production, and lipid content by Phenoliferia glacialis (syn, Rhodotorula glacialis ) DBVPG4875 [ 203 ] and Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae ) SY89 [ 204 ] but other values were found depending on the specific bioprocess conditions [ 119 , 205 ].…”