Nymul Khan

Pacific Northwest National Laboratory | PNNL · Biological Sciences Division

Modern microbial biodesign relies on the principle that well-characterized genetic parts can be reused and reconfigured for different functions. However, this paradigm has only been successful in a limited set of hosts, mostly comprised from common lab strains of Escherichia coli. It is clear that new applications such as chemical sensing and event...

Modern microbial biodesign relies on the principle that well-characterized genetic parts can be reused and reconfigured for different functions. However, this paradigm has only been successful in a limited set of hosts, mostly comprised from common lab strains of Escherichia coli. It is clear that new applications -- such as chemical sensing and ev...

Bile acids are metabolic links between hosts and their gut microbiomes, yet little is known about the roles they play in microbe-to-microbe interactions. Here we present a study designed to investigate the effect that a common probiotic, Lactobacillus acidophilus , has on microbial interactions that lead to formation of secondary bile acids. A mode...

The fundamental question of whether different microbial species will co-exist or compete in a given environment depends on context, composition and environmental constraints. Model microbial systems can yield some general principles related to this question. In this study we employed a naturally occurring co-culture composed of heterotrophic bacter...

The colony algae Botryococcus braunii produces large amounts of C30+ triterpene hydrocarbons. Recent discovery of the associated biosynthetic genes has facilitated the metabolic engineering of these triterpene hydrocarbons in alternative hosts ? where squalene has served as an analytical standard and a closely associated model hydrocarbon biosynthe...

The ability of autotrophic organisms to fix CO2 presents an opportunity to utilize this 'greenhouse gas' as an inexpensive substrate for biochemical production. Unlike conventional heterotrophic microorganisms that consume carbohydrates and amino acids, prokaryotic chemolithoautotrophs have evolved the capacity to utilize reduced chemical compounds...

Triterpene hydrocarbon biosynthesis of the ancient algae Botryococcus braunii was installed into Rhodobacter capsulatus to explore the production of C30 hydrocarbon in a host capable of diverse growth habits - utilizing carbohydrate, sunlight or hydrogen (with CO2 fixation) as alternative energy feedstocks. Engineering an enhanced MEP pathway was a...

We present our progress in producing triterpene fuel precursors from CO2, H2 and O2as part of the ARPA-E electrofuels program. While increasing product titer provides an obvious improvement to process economic feasibility, we also present that the maintenance energy of bacteria, or the energy needed to keep it alive, is a significant economic consi...

The removal of NOx by ultrasonic irradiation is a fairly new area. In our previous works we have looked at the effects of different variables on the absorption of NOx from flue gases in presence of ultrasound. The fractional conversions of NO were found to range from 60% to 85%, while complete removal of SO2 was observed for all the inlet gas conce...

Our overall ARPA-E project goal seeks to produce a renewable hydrocarbon feedstock by the genetic engineering of a C34 branched hyrdrocarbon of Botrococcus braunii into Rhodobacter capsulatus. We have shown the ability of this genetically engineered autotrophic organism to produce C30+ isoprenes from H2, O2 and CO2. My specific component of this pr...

A new method for the determination of peroxydisulfate using ion chromatography has been developed. Elution of peroxydisulfate was effected by isocratic elution using 200 mM NaOH at 40°C. A modification of the method using gradient elution was able to simultaneously determine other common inorganic ions (nitrate, nitrite, sulfate and chloride) down...

The absorption−oxidation of nitric oxide (NO) by aqueous solution of sodium persulfate (Na2S2O8) has been studied in a bubble column reactor operated in semibatch mode. The effects of different process variables such as the persulfate concentration (0.01−0.2 M), temperature (23−90 °C), pH (4−12), sodium chloride concentration (0−0.5 M), and NO conc...

The textile industry in Bangladesh uses a substantial quantity of caustic soda (sodium hydroxide) to clean and prepare fabrics for dyeing. In all textile mills dealing with finishing, particularly with the mercerizing of cotton and mixed cotton fabrics, dilute caustic soda solutions come out as effluent from mercerizing unit. Caustic soda is expens...

The combustion of fossil fuel releases a large amount of NOx and SO2 into the atmosphere which is a major threat to human health and environment. The efficient, cost effective and environmentally friendlier removal of NOx and SO2 from flue gases poses a considerable industrial problem. Ultrasonic oxidation of NOx and SO2 can be a solution. In our p...