User:Lysozymes/Fervidobacterium islandicum

Fervidobacterium islandicum strain AW-1, otherwise known as F. islandicum AW-1, is a Gram-negative, strictly anaerobic, motile, rod-shaped bacterium originally isolated from geothermal hot streams at Sileri (Java Island) in Indonesia. F. islandicum AW-1 is capable of degrading the protein keratin. =Taxonomy=

=Discovery=

Gae-Won Nam and his team of researchers at the Department of Biotechnology and Bioproducts Research Center at Yonsei University isolated Fervidobacterium islandicum from a geothermal hot stream in Indonesia. This work was supported by the Korea Science and Engineering Foundation (KOSEF).

Using samples from the geothermal hot spring, cultures were anaerobically enriched using the Hungate culture technique at 70 °C in EM-1 medium. Phenotypic characterization (Optimal growth temperatures, pH, salinity, substrate characterization, and growth rate studies), DNA-DNA hybridization, electron microscopy, 16s rRNA gene sequencing and analysis, as well as subsequent keratinase enzyme assays on F. islandicum strain AW-1 were all performed by Gae-Won Nam’s team at Yosei University.

=Ecology=

F. islandicum was isolated from the Dieng volcanic system in Sileri, Java Island, Indonesia, in August 1999. Clay-filled geothermal wells made of quartz, chlorite, and calcite that reach 1500-2500 meters underground, creating anaerobic environments that house F. islandicum. The Dieng geothermal resource is a liquid-dominated reservoir containing high-temperature water with a low dissolved-gas content and neutral pH. No other locations have been recorded to harbor F. islandicum. The ecology of F. islandicum has been determined strictly by culturing.

=Physiological Characterization=

F. islandicum is a gram negative, rod-shaped bacterium, measuring 1.8 $$\mu$$m in length. The bacterium appears in chains, pairs, or singly, and is motile. F. islandicum is a thermophile capable of growth at 40-80°C, and has an optimum temperature of 65-70°C. The optimum pH of the bacterium is 7.0, but it is able to grow at a pH of 5-9. No salinity requirements have been reported. F. islandicum is a heterotrophic, strict anaerobe and has a specific growth rate of 0.14hr-1. When conducting research, the bacterium has been grown on modified Thermotoga-Fervidobacterium (TF) medium, containing yeast extract and chicken feathers. F. islandicum is able to ferment a variety of substrates including glucose, raffinose, galactose, arabinose, maltose, ribose, lactose, mannose, xylose, fructose, pyruvate. F. islandicum is capable of growth on cellulose, starch, yeast extract. It has also been shown to hydrolyze gelatin. F. islandicum produces H2, CO2, and acetate as fermentation products. H2S is also produced during some fermentation processes. When metabolizing glucose, F. islandicum uses a $$\beta$$-galactosidase that is resistant to glucose inhibition, which results in faster degradation and could be industrially useful because of its thermostability. F. islandicum is capable of degrading completely 0.8% w/v native chicken feathers in 48 hours at 70°C. The exact pathway is yet to be determined.

=Genomics and Metabolic Reconstruction=

The F. islandicum genome was sequenced using a PacBio single molecule real time II (SMRT) sequencer and preprocessing was done using the hierarchical genome assembly process (HGAP), a protocol used to produce long, accurate sequences. The genome was annotated with NCBI COG and prokaryotic genome automatic annotation pipeline (PGAAP) within the NCBI database. The genome contains 2,359,755 base pair s, 64 genes that encode RNA molecules, and 2184 genes that encode proteins. The GC content is 40.74%. The F. islandicum genome was sequenced in part as a model organism to study keratin degradation, as the pathway is not well understood. Annotation of its genome revealed many proteolytic enzymes, and several enzymes involved in disulfide bond breakage, such as cytosine desulfurase and thioredoxindisulfide reductase, which are candidates for proteins responsible for keratinolysis.

=Significance =

Thermophilic bacteria are a valuable source for enzymes that have the capability of tolerating harsh conditions and consequently are of possible industrial value. F. islandicum is of particular interest due to the discovery of a novel $$\beta$$-galactosidase enzyme called FiBgl1A. $$\beta$$-galactosidase is an enzyme that cleaves the β-1,4-glycosidic-link in cellulose and lactose into simple sugars such as glucose and galactose. $\beta$-galactosidase activity is inhibited by glucose, halting the breakdown of complex carbohydrates. FiBgl1A is resistant to the inhibition of glucose and is both thermoactive and thermostable. These characteristics make FiBgl1A a candidate for industrial applications. For instance, β-glucosidase has valuable applications in food industries that manufacture products for lactose-intolerant people.

F. islandicum also possesses a set of keratinases and other enzymes that have the ability to degrade feathers. Recent increases in poultry meat has caused a large accumulation of native feathers. Feathers are mainly composed of keratin, a fibrous structural protein composed of type I and type II intermediate filaments. These feathers don’t have many industrial applications and end up being thrown out in landfills or chemically treated, yielding environmentally harmful by-products. The degradation of keratin requires more than just keratin-specific proteases due to its complex structure. There are several other enzymes involved in the breakdown of insoluble keratin polymers that have been identified in F. islandicum , thus providing environmentally safe procedures to treat keratin-rich solid waste such as chicken feathers.

=References=