Nitrospira moscoviensis: Difference between revisions
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{{Taxobox |
{{Taxobox |
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| name = ''Nitrospira moscoviensis'' |
| name = ''Nitrospira moscoviensis'' |
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| regnum = [[Bacterium|Bacteria]] |
| regnum = [[Bacterium|Bacteria]] |
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| phylum = [[ |
| phylum = [[Nitrospirae]] |
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| classis = [[Nitrospira]] |
| classis = [[Nitrospira]] |
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| ordo = [[Nitrospirales]] |
| ordo = [[Nitrospirales]] |
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| species = '''''N. moscoviensis''''' |
| species = '''''N. moscoviensis''''' |
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| binomial = ''Nitrospira moscoviensis'' |
| binomial = ''Nitrospira moscoviensis'' |
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| binomial_authority = Garrity et al. 2001<ref>{{cite book|editor1-last=Garrity|editor1-first=George|editor2-last=Castenholz|editor2-first=Richard W.|editor3-last=Boone|editor3-first=David R.|title=Bergey's Manual of Systematic Bacteriology|date=2001|publisher=New York, NY|location=New York, NY|isbn=978-0-387-21609-6|pages=451-453|edition=2nd}}</ref> |
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| binomial_authority = Ehrich et al., 1995 |
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'''''Nitrospira moscoviensis''''' is a bacteria in the phylum [[Nitrospirae]]. It is the second member of this genus, discovered in 1995 from a corroded iron pipe in a Moscow heating system. It is a [[gram-negative]] [[nitrite]]-[[oxidation|oxidising]]<ref name="LitmanChiu2006">{{cite journal|last1=Litman|first1=Matthew R|last2=Chiu|first2=Norman HL|last3=Wang|first3=James|title=Specific recognition of non-denatured nitrite-oxidizing system ofNitrospira moscoviensis by monoclonal antibody Hyb 153-3|journal=Journal of Chemical Technology & Biotechnology|volume=81|issue=3|year=2006|pages=318–321|issn=0268-2575|doi=10.1002/jctb.1397}}</ref> organism with a helical to vibroid morphology 0.9-2.2 x 0.2-0.4 [[micrometre]]s in size.<ref>{{cite journal | author = Ehrich S, Behrens D, Lebedeva E, Ludwig W, Bock E | title = A new obligately chemolithoautotrophic, nitrite-oxidizing bacterium, Nitrospira moscoviensis sp. nov. and its phylogenetic relationship. | journal = Arch Microbiol | volume = 164 | issue = 1 | pages = 16–23 | year = 1995 | pmid = 7646315 | doi = 10.1007/BF02568729}}</ref> It is non-[[motile]], has an enlarged [[periplasmic space]] and lacks intracytoplasmic membranes and [[carboxysome]]s. It is [[Microbial metabolism|chemolithoautotrophic]]. |
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'''''Nitrospira moscoviensis''''' was the second bacterium classified under the most diverse nitrite-oxidizing bacteria phylum, ''Nitrospirae''.<ref name=":0" /><ref name=":4" /> It is a [[Gram-negative bacteria|gram-negative]], non-motile, [[facultative]] lithoauthotropic bacterium that was discovered in [[Moscow]], Russia in 1995.<ref name=":0">{{cite journal|last1=Ehrich|first1=S|last2=Behrens|first2=D|last3=Ludwig|first3=W|last4=Bock|first4=E|title=A new obligately chemolithoautotrophic, nitrite-oxidizing bacterium, nitrospira moscoviensis sp. nov. and its phylogenetic relationship|journal=Arch Microbiol|date=1995|volume=164|issue=1|pages=16-23|doi=10.1007/BF02568729}}</ref> The genus name, [[Nitrospira|''Nitrospira'']], originates from the prefix “nitro” derived from nitrite, the microbe’s [[electron donor]] and “spira” meaning coil or [[Spiral bacteria|spiral]] derived from the microbe’s shape.<ref name=":1">{{cite journal|last1=Watson|first1=S.W.|last2=Bock|first2=E.|last3=Valois|first3=F.W.|last4=Waterbury|first4=J.B.|last5=Schlosser|first5=U|title=Nitrospira marina gen. nov. sp. nov.: a chemolitho- trophic nitrite-oxidizing bacterium|journal=Arch Microbiol|date=1986|volume=144|issue=1|pages=1-7|doi=10.1007/BF00454947}}</ref> The species name, ''moscoviensis'', is derived from Moscow, where the species was first discovered.<ref name=":1" /> ''N. moscoviensis'' could potentially be used in the production of [[Biodegradable polymer|bio-degradable polymers]].<ref name=":0" /> |
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{{reflist}} |
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== History == |
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In 1995, Silke Ehrich discovered ''Nitrospira moscoviensis'' in a sample taken from an eroded iron pipe.<ref name=":0" /> The pipe was a part of a heating system in Moscow, Russia.<ref name=":0" /> The rust was transferred to a culture where cells could be isolated.<ref name=":0" /> For optimum growth, Ehrich and his team cultivated the cells on a mineral salt medium at a temperature of 39° C and at a pH of 7.6-8.0.<ref name=":0" /> |
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*{{cite journal|last1=Neubacher|first1=Elke|last2=Prast|first2=Mario|last3=Cleven|first3=Ernst-Josef|last4=Berninger|first4=Ulrike-Gabriele|title=Ciliate grazing on Nitrosomonas europaea and Nitrospira moscoviensis: Is selectivity a factor for the nitrogen cycle in natural aquatic systems?|journal=Hydrobiologia|volume=596|issue=1|year=2007|pages=241–250|issn=0018-8158|doi=10.1007/s10750-007-9100-7}} |
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== Morphology == |
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*{{cite journal|last1=Lucker|first1=S.|last2=Wagner|first2=M.|last3=Maixner|first3=F.|last4=Pelletier|first4=E.|last5=Koch|first5=H.|last6=Vacherie|first6=B.|last7=Rattei|first7=T.|last8=Damste|first8=J. S. S.|last9=Spieck|first9=E.|last10=Le Paslier|first10=D.|last11=Daims|first11=H.|title=A Nitrospira metagenome illuminates the physiology and evolution of globally important nitrite-oxidizing bacteria|journal=Proceedings of the National Academy of Sciences|volume=107|issue=30|year=2010|pages=13479–13484|issn=0027-8424|doi=10.1073/pnas.1003860107}} |
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''Nitrospira moscoviensis'' is classified as being [[Gram-negative bacteria|gram-negative]], non-motile, and having a curved [[Bacillus (shape)|rod shape]].<ref name=":0" /> The curved rods are approximately 0.9-2.2 µm long x 0.2-0.4 µm wide.<ref name=":0" /> ''N. moscoviensis'' can exist in both aquatic and terrestrial habitats and reproduces using [[Fission (biology)|binary fission]].<ref name=":0" /> Defining features of ''N. moscoviensis'' is the absence of intra-[[Cytoplasmic membrane|cytoplasmic membranes]] and carboxysomes possession of a flatulent [[periplasmic space]].<ref name=":2" /> |
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== Metabolism == |
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''Nitrospira moscoviensis'' is a facultative [[lithoautotroph]] commonly referred to as a [[chemolithoautotroph]].<ref name=":0" /> In [[aerobic]] environments, ''N. moscoviensis'' obtains energy by [[oxidizing]] nitrite to nitrate.<ref name=":2">{{cite journal|last1=Spieck|first1=E.|last2=Ehrich|first2=S|last3=Aamand|first3=J|last4=Bock|first4=E.|title=Isolation and immunocytochemical location of the nitrite-oxidizing system in nitrospira moscoviensis|journal=Arch Microbiol|date=1998|volume=169|issue=3|pages=225-230|doi=10.1007/s002030050565}}</ref> Without the element [[molybdenum]], the nitrite-oxidizing system will not function.<ref name=":2" /> When ''N. moscoviensis'' is in nitrite free environments it can use aerobic hydrogen oxidation.<ref name=":4" /> When ''N. moscoviensis'' reduces nitrite using hydrogen as an electron donor growth is blocked.<ref name=":4" /> A key difference in ''N. moscoviensis’'' nitrite-oxidizing system is location; unlike most nitrate oxidizing systems, it is not located in the [[cytoplasmic membrane]].<ref name=":2" /> Kirstein and Bock (1993) implied that the location of the nitrite-oxidizing system corresponds directly to ''N. moscoviensis'' having an enlarged [[periplasmic space]].<ref>{{cite journal|last1=Kirstein|first1=K|last2=Bock|first2=E|title=Close genetic relationship between Ni- trobacter hamburgensis nitrite oxidoreductase and Escherichia coli nitrate reductases|journal=Arch Microbiol|date=1993|volume=160|issue=6|pages=447-453|doi=10.1007/BF00245305}}</ref> By oxidizing nitrate outside of the cytoplasmic membrane, a permease nitrite system is not needed for the [[Proton gradient|proton gradient.]]<ref name=":2" /> The exocytoplasmic oxidation of nitrite also prevents build-up of toxic nitrite within the cytoplasm.<ref name=":2" /> Another important metabolism ability for ''N. moscoviensis'' is its ability to cleave urea to ammonia and CO<sub>2</sub>.<ref name=":4" /> The ability to use urea comes directly from the presence of urease encoding genes which is interesting because most nitrite-oxidizing bacteria are unable to use ammonia as an energy source.<ref name=":4" /> Urease encoding genes function by catalyzing urea hydrolysis to form ammonia and carbamate.<ref name=":4" /> |
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*[http://microbewiki.kenyon.edu/index.php/Nitrospira MicrobeWiki – Nitrospira] |
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*{{EOL|1001854|Nitrospira moscoviensis}} |
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*[http://www.bacterio.net/n/nitrospira.html LPSN] |
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== Ecology == |
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{{DEFAULTSORT:Nitrospira moscoviensis}} |
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''Nitrospira moscoviensis'' grows in temperatures from 33 to 40°C and pH 7.6-8.0 with an optimal nitrite concentration of 0.35 nM.<ref name=":0" /> ''Nitrospira moscoviensis'' plays a key role in the two-step [[Nitrogen Cycle]] process. <ref name=":4">{{cite journal|last1=Koch|first1=H.|last2=Luecker|first2=S.|last3=Albertsen|first3=M.|last4=Kitzinger|first4=K.|last5=Herbold|first5=K.|last6=Spieck|first6=E.|last7=Daims|first7=H.|title=Expanded metabolic versatility of ubiquitous nitrite-oxidizing bacteria from the genus nitrospira|journal=Proceedings of the National Academy of Sciences, USA|date=2015|volume=112|issue=36}}</ref> The first step of [[Nitrification]] requires an ammonia-oxidizing bacterium (AOB) or ammonia-oxidizing archaeon (AOA) followed by a nitrite-oxidizing bacterium (NOB).<ref name=":4" /> The unique capability of ''N. moscoviensis'' to cleave [[urea]] into [[ammonia]] and [[carbon dioxide]] allows for a [[symbiotic relationship]] with ammonia-oxidizing microorganisms (AOM) that lack this urease-production ability also know as negative AOM. <ref name=":4" /> A correlation in environment preferences between ''Nitrospira'' species with ''nxrB'' gene encoding the β-subunit of nitro-oxidoreductase and AOM species with ''amoA'' gene further confirmed this relationship.<ref name=":5">{{Cite journal|last=Pester|first=Michael|last2=Maixner|first2=Frank|last3=Berry|first3=David|last4=Rattei|first4=Thomas|last5=Koch|first5=Hanna|last6=Lücker|first6=Sebastian|last7=Nowka|first7=Boris|last8=Richter|first8=Andreas|last9=Spieck|first9=Eva|date=2014-10-01|title=NxrB encoding the beta subunit of nitrite oxidoreductase as functional and phylogenetic marker for nitrite-oxidizing Nitrospira|url=http://onlinelibrary.wiley.com/doi/10.1111/1462-2920.12300/abstract|journal=Environmental Microbiology|language=en|volume=16|issue=10|pages=3055–3071|doi=10.1111/1462-2920.12300|issn=1462-2920}}</ref> ''N. moscoviensis'' provides ammonia via [[hydrolysis]] of urea to these ammonia-oxidizing microorganisms which in turn produce nitrite, the primary energy source of ''N. moscoviensis''.<ref name=":4" /> The relationship between ureolytic nitrite-oxidizing bacteria and negative AOM is called [[Reciprocal feeding|reciprocal feedin]]<nowiki/>g.<ref name=":4" /> Thus far, ''Nitrospira'' species have been recognized in natural environments as the primary vehicle for nitrite oxidation including soils, [[Activated sludge|activated-sludge]], ocean and fresh water, [[Hot spring|hot springs]], and [[water treatment plants]].<ref name=":6">{{Cite journal|last=Nowka|first=Boris|last2=Off|first2=Sandra|last3=Daims|first3=Holger|last4=Spieck|first4=Eva|date=2015-03-01|title=Improved isolation strategies allowed the phenotypic differentiation of two Nitrospira strains from widespread phylogenetic lineages|url=http://femsec.oxfordjournals.org/content/91/3/fiu031|journal=FEMS Microbiology Ecology|language=en|volume=91|issue=3|pages=fiu031|doi=10.1093/femsec/fiu031|issn=1574-6941|pmid=25764560}}</ref> |
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== Genomics == |
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[[Category:Nitrospirae]] |
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Following its isolation, ''N. moscoviensis''’s genome was sequenced by Dr. Ehrich et al.<ref name=":0" /> Its 4.59 Mb [[genome]] has a GC content of 56.9+/-0.4 mol% with a predicted 4,863 [[Coding region|coding sequences]].<ref name=":0" /><ref name=":4" /> ''N. moscoviensis''<nowiki/>'s 16S rRNA gene sequences were found to be 88.9% similar to ''N. marina''’s.<ref name=":0" /> Despite its relatively low similarity to ''N. marina'', ''N. moscoviensis'' was classified within the ''Nitrospirae'' phylum primarily due to shared morphological features including the presence of an enlarged [[Periplasm|periplasmic]] space.<ref name=":0" /> |
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''N. moscoviensis''’s fully sequenced genome has provided useful [[Phylogenetics|phylogenetic]] insights [[Metagenomics: An Alternative Approach to Genomics|beyond the scope]] of 16S rRNA sequence studies.<ref name=":5" /> The discovery of the gene encoding the β-subunit of nitrite-[[oxidoreductase]], ''nxrB'', from ''N. moscoviensis'' as a functional genetic marker of ''Nitrospira'', not only confirmed previous 16S rRNA phylogenetic classifications within the phylum, but revealed a new understanding of ''Nitrospira''’s richness in [[Terrestrial environment|terrestrial environments]].<ref name=":5" /> The phylum has expanded from two bacteria, ''N. marina'' and ''N. moscoviensis'', to a 6-branched genera composed of a characteristically diverse group of nitrite-oxidizing bacteria with ''N. moscoviensis'' positioned in lineage II.<ref name=":6" /> |
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{{bacteria-stub}} |
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== Biotechnology == |
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The cytoplasm of ''Nitrospira moscoviensis'' contains [[polyhydroxybutyrate]] (PHB) granules.<ref name=":0" /> PHB granules are [[Polyhydroxyalkanoates|polyhydroxyalkanoate]] (PHA) [[Polymer|polymers]].<ref name=":3">{{cite journal|last1=Ojumu|first1=T.V.|last2=Solomon|first2=B.O|title=Production of Polyhydroxyalkanoates, a bacterial biodegradable polymer|journal=African Journal of Biotechnology|date=2004|volume=3|issue=1|pages=18-24|url=https://tspace.library.utoronto.ca/bitstream/1807/3487/1/jb04003.pdf}}</ref> PHB granules are produced by ''N. moscoviensis'' when the presence of nitrate is limited.<ref name=":3" /> When nutrient limitations are no longer present, ''N. moscoviensis'' degrades PHB granules using [[Enzyme|enzymes]], and recycling the degraded materials for functional use as a carbon source.<ref name=":3" /> [[Synthetic polymers]] are used to make most plastics, synthetic polymers are [[Non biodegradable|non-biodegradable]] and contribute negatively to the environment.<ref name=":3" /> Unlike synthetic polymers polyhydroxybutyrate is a [[biopolymer]], meaning it can be [[Biodegradation|bio-degraded]].<ref name=":3" /> PHB can be utilized for packaging, medical purposes like reconstructive surgery, and personal hygiene products.<ref name=":3" /> |
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Revision as of 15:38, 26 April 2016
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| Nitrospira moscoviensis Garrity et al. 2001[1]
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Nitrospira moscoviensis was the second bacterium classified under the most diverse nitrite-oxidizing bacteria phylum, Nitrospirae.[2][3] It is a gram-negative, non-motile, facultative lithoauthotropic bacterium that was discovered in Moscow, Russia in 1995.[2] The genus name, Nitrospira, originates from the prefix “nitro” derived from nitrite, the microbe’s electron donor and “spira” meaning coil or spiral derived from the microbe’s shape.[4] The species name, moscoviensis, is derived from Moscow, where the species was first discovered.[4] N. moscoviensis could potentially be used in the production of bio-degradable polymers.[2]
History
In 1995, Silke Ehrich discovered Nitrospira moscoviensis in a sample taken from an eroded iron pipe.[2] The pipe was a part of a heating system in Moscow, Russia.[2] The rust was transferred to a culture where cells could be isolated.[2] For optimum growth, Ehrich and his team cultivated the cells on a mineral salt medium at a temperature of 39° C and at a pH of 7.6-8.0.[2]
Morphology
Nitrospira moscoviensis is classified as being gram-negative, non-motile, and having a curved rod shape.[2] The curved rods are approximately 0.9-2.2 µm long x 0.2-0.4 µm wide.[2] N. moscoviensis can exist in both aquatic and terrestrial habitats and reproduces using binary fission.[2] Defining features of N. moscoviensis is the absence of intra-cytoplasmic membranes and carboxysomes possession of a flatulent periplasmic space.[5]
Metabolism
Nitrospira moscoviensis is a facultative lithoautotroph commonly referred to as a chemolithoautotroph.[2] In aerobic environments, N. moscoviensis obtains energy by oxidizing nitrite to nitrate.[5] Without the element molybdenum, the nitrite-oxidizing system will not function.[5] When N. moscoviensis is in nitrite free environments it can use aerobic hydrogen oxidation.[3] When N. moscoviensis reduces nitrite using hydrogen as an electron donor growth is blocked.[3] A key difference in N. moscoviensis’ nitrite-oxidizing system is location; unlike most nitrate oxidizing systems, it is not located in the cytoplasmic membrane.[5] Kirstein and Bock (1993) implied that the location of the nitrite-oxidizing system corresponds directly to N. moscoviensis having an enlarged periplasmic space.[6] By oxidizing nitrate outside of the cytoplasmic membrane, a permease nitrite system is not needed for the proton gradient.[5] The exocytoplasmic oxidation of nitrite also prevents build-up of toxic nitrite within the cytoplasm.[5] Another important metabolism ability for N. moscoviensis is its ability to cleave urea to ammonia and CO2.[3] The ability to use urea comes directly from the presence of urease encoding genes which is interesting because most nitrite-oxidizing bacteria are unable to use ammonia as an energy source.[3] Urease encoding genes function by catalyzing urea hydrolysis to form ammonia and carbamate.[3]
Ecology
Nitrospira moscoviensis grows in temperatures from 33 to 40°C and pH 7.6-8.0 with an optimal nitrite concentration of 0.35 nM.[2] Nitrospira moscoviensis plays a key role in the two-step Nitrogen Cycle process. [3] The first step of Nitrification requires an ammonia-oxidizing bacterium (AOB) or ammonia-oxidizing archaeon (AOA) followed by a nitrite-oxidizing bacterium (NOB).[3] The unique capability of N. moscoviensis to cleave urea into ammonia and carbon dioxide allows for a symbiotic relationship with ammonia-oxidizing microorganisms (AOM) that lack this urease-production ability also know as negative AOM. [3] A correlation in environment preferences between Nitrospira species with nxrB gene encoding the β-subunit of nitro-oxidoreductase and AOM species with amoA gene further confirmed this relationship.[7] N. moscoviensis provides ammonia via hydrolysis of urea to these ammonia-oxidizing microorganisms which in turn produce nitrite, the primary energy source of N. moscoviensis.[3] The relationship between ureolytic nitrite-oxidizing bacteria and negative AOM is called reciprocal feeding.[3] Thus far, Nitrospira species have been recognized in natural environments as the primary vehicle for nitrite oxidation including soils, activated-sludge, ocean and fresh water, hot springs, and water treatment plants.[8]
Genomics
Following its isolation, N. moscoviensis’s genome was sequenced by Dr. Ehrich et al.[2] Its 4.59 Mb genome has a GC content of 56.9+/-0.4 mol% with a predicted 4,863 coding sequences.[2][3] N. moscoviensis's 16S rRNA gene sequences were found to be 88.9% similar to N. marina’s.[2] Despite its relatively low similarity to N. marina, N. moscoviensis was classified within the Nitrospirae phylum primarily due to shared morphological features including the presence of an enlarged periplasmic space.[2]
N. moscoviensis’s fully sequenced genome has provided useful phylogenetic insights beyond the scope of 16S rRNA sequence studies.[7] The discovery of the gene encoding the β-subunit of nitrite-oxidoreductase, nxrB, from N. moscoviensis as a functional genetic marker of Nitrospira, not only confirmed previous 16S rRNA phylogenetic classifications within the phylum, but revealed a new understanding of Nitrospira’s richness in terrestrial environments.[7] The phylum has expanded from two bacteria, N. marina and N. moscoviensis, to a 6-branched genera composed of a characteristically diverse group of nitrite-oxidizing bacteria with N. moscoviensis positioned in lineage II.[8]
Biotechnology
The cytoplasm of Nitrospira moscoviensis contains polyhydroxybutyrate (PHB) granules.[2] PHB granules are polyhydroxyalkanoate (PHA) polymers.[9] PHB granules are produced by N. moscoviensis when the presence of nitrate is limited.[9] When nutrient limitations are no longer present, N. moscoviensis degrades PHB granules using enzymes, and recycling the degraded materials for functional use as a carbon source.[9] Synthetic polymers are used to make most plastics, synthetic polymers are non-biodegradable and contribute negatively to the environment.[9] Unlike synthetic polymers polyhydroxybutyrate is a biopolymer, meaning it can be bio-degraded.[9] PHB can be utilized for packaging, medical purposes like reconstructive surgery, and personal hygiene products.[9]
References
- ^ Garrity, George; Castenholz, Richard W.; Boone, David R., eds. (2001). Bergey's Manual of Systematic Bacteriology (2nd ed.). New York, NY: New York, NY. pp. 451–453. ISBN 978-0-387-21609-6.
- ^ a b c d e f g h i j k l m n o p q Ehrich, S; Behrens, D; Ludwig, W; Bock, E (1995). "A new obligately chemolithoautotrophic, nitrite-oxidizing bacterium, nitrospira moscoviensis sp. nov. and its phylogenetic relationship". Arch Microbiol. 164 (1): 16–23. doi:10.1007/BF02568729.
- ^ a b c d e f g h i j k l Koch, H.; Luecker, S.; Albertsen, M.; Kitzinger, K.; Herbold, K.; Spieck, E.; Daims, H. (2015). "Expanded metabolic versatility of ubiquitous nitrite-oxidizing bacteria from the genus nitrospira". Proceedings of the National Academy of Sciences, USA. 112 (36).
- ^ a b Watson, S.W.; Bock, E.; Valois, F.W.; Waterbury, J.B.; Schlosser, U (1986). "Nitrospira marina gen. nov. sp. nov.: a chemolitho- trophic nitrite-oxidizing bacterium". Arch Microbiol. 144 (1): 1–7. doi:10.1007/BF00454947.
- ^ a b c d e f Spieck, E.; Ehrich, S; Aamand, J; Bock, E. (1998). "Isolation and immunocytochemical location of the nitrite-oxidizing system in nitrospira moscoviensis". Arch Microbiol. 169 (3): 225–230. doi:10.1007/s002030050565.
- ^ Kirstein, K; Bock, E (1993). "Close genetic relationship between Ni- trobacter hamburgensis nitrite oxidoreductase and Escherichia coli nitrate reductases". Arch Microbiol. 160 (6): 447–453. doi:10.1007/BF00245305.
- ^ a b c Pester, Michael; Maixner, Frank; Berry, David; Rattei, Thomas; Koch, Hanna; Lücker, Sebastian; Nowka, Boris; Richter, Andreas; Spieck, Eva (2014-10-01). "NxrB encoding the beta subunit of nitrite oxidoreductase as functional and phylogenetic marker for nitrite-oxidizing Nitrospira". Environmental Microbiology. 16 (10): 3055–3071. doi:10.1111/1462-2920.12300. ISSN 1462-2920.
- ^ a b Nowka, Boris; Off, Sandra; Daims, Holger; Spieck, Eva (2015-03-01). "Improved isolation strategies allowed the phenotypic differentiation of two Nitrospira strains from widespread phylogenetic lineages". FEMS Microbiology Ecology. 91 (3): fiu031. doi:10.1093/femsec/fiu031. ISSN 1574-6941. PMID 25764560.
- ^ a b c d e f Ojumu, T.V.; Solomon, B.O (2004). "Production of Polyhydroxyalkanoates, a bacterial biodegradable polymer" (PDF). African Journal of Biotechnology. 3 (1): 18–24.