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Viamajala, Sridhar

Publications and source records attributed to Viamajala, Sridhar.

15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

A comprehensive strategy for stable, high productivity cultivation of microalgae with controllable biomass composition

This project was performed primarily as a partnership between three Universities – The University of Toledo (UToledo), Montana State University (MSU) and The University of North Carolina at Chapel Hill (UNC). North Carolina State University also contributed to the project through a sub-subcontract. The project developed fundamental and applied knowhow for cultivation systems that are not restricted by (i) proximate availability of flue gas or other high concentration CO 2 sources and (ii) the energy and infrastructure burden to deliver CO 2 over long distances. To overcome these constraints, this project focused on cultivation of alkaliphilic algal cultures in high pH, high alkalinity media (pH>10, alkalinity >100mEq) and demonstrated high biomass productivity, improvement of biomass composition for fuel production, and culture stability. The high media alkalinity ensured availability of sufficient HCO 3 - in solution for high rates of carbon fixation while the high pH of the media facilitated rapid scavenging of atmospheric CO 2 . Overall, the direct air capture rates (DAC) in our system were sufficient to achieve high biomass productivities using atmospheric CO 2 alone. The project also developed and validated toolkits related to metabolic flux modeling and microbiome characterization.

09 BIOMASS FUELS↗
DOE OSTI2022

Genome sequence, phylogenetic analysis, and structure-based annotation reveal metabolic potential of Chlorella sp. SLA-04

Algae are a broad class of photosynthetic eukaryotes that are phylogenetically and physiologically diverse. Most of the phylogenetic diversity has been inferred from 18S rDNA sequencing since there are only a few complete genomes available in public databases. Here we use ultra-long-read Nanopore sequencing to determine a gapless, telomere-to-telomere complete genome sequence of Chlorella sp. SLA-04, previously described as Chlorella sorokiniana SLA-04. Chlorella sp. SLA-04 is a green alga that grows to high cell density in a wide variety of environments - high and neutral pH, high and low alkalinity, and high and low salinity. SLA-04's ability to grow in high pH and high alkalinity media without external CO 2 supply is favorable for large-scale algal biomass production. Phylogenetic analysis performed using ribosomal DNA and conserved protein sequences consistently reveal that Chlorella sp. SLA-04 forms a distinct lineage from other strains of Chlorella sorokiniana. We complement traditional genome annotation methods with high throughput structural predictions and demonstrate that this approach expands functional prediction of the SLA-04 proteome. Genomic analysis of the SLA-04 genome identifies the genes capable of utilizing TCA cycle intermediates to replenish cytosolic acetyl-CoA pools for lipid production. We also identify a complete metabolic pathway for sphingolipid anabolism that may allow SLA-04 to readily adapt to changing environmental conditions and facilitate robust cultivation in mass production systems. Altogether, this work clarifies the phylogeny of Chlorella sp. SLA-04 within Trebouxiophyceae and demonstrates how structural predictions can be used to improve annotation beyond sequencebased methods.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

High yield algal biomass production without concentrated CO2 supply under open pond conditions

Methods and systems for efficient culturing of algae in open ponds. Further, the methods include a method for culturing algae in an open pond medium that is free of any concentrated supply of CO2, and no concentrated source of CO2 is used to supply carbon for culturing the algae. Also, the algae are cultured in the open pond which has a pH above 9.5. In addition, the open pond medium has incorporated therein an inorganic carbon buffer at a specified concentration under conditions for obtaining an increased biomass. Also, the pH above 9.5 permits sufficient increased fixation of atmospheric CO2 into the open pond medium.

Pendyala, Brahmaiah↗
DOE OSTI2019

Integration of Nutrient and Water Recycling for Sustainable Algal Biorefineries (Final Report)

This project was performed primarily as a partnership between three Universities – The University of Toledo, Montana State University and The University of North Carolina at Chapel Hill – and the industrial collaborator Clearas Water LLC. The University of Minnesota also contributed in the last year of the project. The project addressed constraints/barriers throughout the process of production of biofuels from microalgae – cultivation, harvesting and conversion processes for fuels and value-added chemicals. The most important outcomes of this project were related to (1) developing a microalgae cultivation strategy in alkaline environments to improve culture stability, decrease reliance on concentrated CO 2 sources and high biofuel precursor yields; (2) fundamental understanding of microbial communities in algal/phototrophic environments to allow development of strategies for management of productive algal cultures; (3) low-cost and low-energy harvesting via temperature-sensitive hydrogels for recycling of water and unused nutrients and other media components; (4) development of conversion methods that generate high-value co-products, in addition to fuels, and also provide means for nutrient recycling; and (5) expanding the scope of current LCA/TEA models to inform potential investment in algal biorefineries.

09 BIOMASS FUELS↗
DOE OSTI2018

Cross metathesis approach to C11-C13 fatty-chain amino esters from oleic acid derivatives

A concise method of producing nylon 11, 12, or 13 precursors from oleic acid or an ester of oleic acid is described. The method involves cross-metathesis reactions as the key C--C bond formation step. Subsequent steps are provided to convert the metathesis product to the corresponding nylon precursors. Also provided are the products of the method.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Production of lipid and carbohydrate from microalgae without compromising biomass productivities: Role of Ca and Mg

We report the cultivation of Chlorella sorokiniana str. SLA-04 in media containing trace amounts of Ca and Mg. The differences in productivities of biomass, lipids and carbohydrates were assessed relative to cultures grown in standard media (BG-11) that contain approximately 8 × higher concentration of Ca and 30 × higher concentration of Mg. Culture performance in N-limited standard media was also investigated. In addition to growth and accumulation of storage products (lipid and carbohydrate), we measured the utilization of N, Ca and Mg and monitored changes in cell size and photosynthetic activity. Our results showed that limitation of Ca or Mg did not inhibit cell replication and culture growth. On the contrary, Ca-limited (Ca L ) cultures had ~30% higher biomass productivity relative to the control with excessive nutrients possibly due to improvement in cell wall flexibility and cell division. We also observed that Ca L and Mg-limited (Mg L ) cultures had nearly 3-fold higher lipid concentration (measured as fatty acid methyl ester) and 50% higher carbohydrate concentration than the nutrient excess control cultures. Simultaneous culture growth and lipid accumulation in Ca L and Mg L cultures suggest that de novo synthesis was the primary mechanism for lipid accumulation in Ca/Mg-limited media. Overall, our study demonstrates that micronutrient optimization, in addition to optimization of macronutrients, could significantly improve microalgal biorefinery yields.

09 BIOMASS FUELS↗