Editing Bioreactor (section)

==Types==

===Photobioreactor===
[[File:Bioreaktor quer2.jpg|thumb|upright|[[Moss bioreactor|Moss photobioreactor]] with ''[[Physcomitrella patens]]'']]
A [[photobioreactor]] (PBR) is a bioreactor which incorporates some type of light source (that may be natural sunlight or artificial illumination). Virtually any [[translucent]] container could be called a PBR, however the term is more commonly used to define a closed system, as opposed to an open [[storage tank]] or [[pond]].
Photobioreactors are used to grow small [[phototroph]]ic organisms such as [[cyanobacteria]], [[alga]]e, or [[moss]] plants.<ref>{{cite journal |last1=Decker |first1=Eva L. |last2=Reski |first2=Ralf |title=Current achievements in the production of complex biopharmaceuticals with moss bioreactors |journal=Bioprocess and Biosystems Engineering |date=14 August 2007 |volume=31 |issue=1 |pages=3–9 |doi=10.1007/s00449-007-0151-y |pmid=17701058 |s2cid=4673669 }}</ref> These organisms use light through [[photosynthesis]] as their [[energy]] source and do not require [[sugar]]s or [[lipid]]s as energy
source. Consequently, risk of [[contamination]] with other organisms like [[bacterium|bacteria]] or [[fungus|fungi]] is lower in photobioreactors when compared to bioreactors for [[heterotroph]] organisms.{{citation needed|date=October 2019}}

===Sewage treatment===
Conventional [[sewage treatment]] utilises bioreactors to undertake the main purification processes. In some of these systems,  a chemically inert medium with very high surface area is provided as a substrate for the growth of  biological film.  Separation of excess biological film takes place in  settling tanks or cyclones. In other systems [[Water aeration#Aeration methods|aerator]]s supply oxygen to the sewage and biota to create [[activated sludge]] in which the biological component is freely mixed in the liquor in "flocs". In these processes, the liquid's [[biochemical oxygen demand]] (BOD) is reduced sufficiently to render the contaminated water fit for reuse. The biosolids can be collected for further processing, or dried and used as fertilizer. An extremely simple version of a sewage bioreactor is a septic tank whereby the sewage is left in situ, with or without additional media to house bacteria. In this instance, the biosludge itself is the primary host for the bacteria.{{citation needed|date=October 2019}}

===Bioreactors for specialized tissues===
[[File:Loading bioreactor.jpg|thumb|A bioreactor used to ferment ethanol from corncob waste being loaded with yeast]]
Many cells and tissues, especially mammalian ones, must have a surface or other structural support in order to grow, and agitated environments are often destructive to these cell types and tissues. Higher organisms, being [[Auxotrophy|auxotrophic]], also require highly specialized growth media. This poses a challenge when the goal is to culture larger quantities of cells for therapeutic production purposes, and a significantly different design is needed compared to industrial bioreactors used for growing protein expression systems such as yeast and bacteria.{{citation needed|date=October 2019}}

Many research groups have developed novel bioreactors for growing specialized tissues and cells on a structural scaffold, in attempt to recreate organ-like tissue structures ''in-vitro''. Among these include tissue bioreactors that can grow heart tissue,<ref>{{cite journal |last1=Bursac |first1=N. |last2=Papadaki |first2=M. |last3=Cohen |first3=R. J. |last4=Schoen |first4=F. J. |last5=Eisenberg |first5=S. R. |last6=Carrier |first6=R. |last7=Vunjak-Novakovic |first7=G. |last8=Freed |first8=L. E. |title=Cardiac muscle tissue engineering: toward an in vitro model for electrophysiological studies |journal=American Journal of Physiology. Heart and Circulatory Physiology |date=1 August 1999 |volume=277 |issue=2 |pages=H433–H444 |doi=10.1152/ajpheart.1999.277.2.h433 |pmid=10444466 }}</ref><ref>{{cite journal |last1=Carrier |first1=Rebecca L. |last2=Papadaki |first2=Maria |last3=Rupnick |first3=Maria |last4=Schoen |first4=Frederick J. |last5=Bursac |first5=Nenad |last6=Langer |first6=Robert |last7=Freed |first7=Lisa E. |last8=Vunjak-Novakovic |first8=Gordana |title=Cardiac tissue engineering: Cell seeding, cultivation parameters, and tissue construct characterization |journal=Biotechnology and Bioengineering |date=5 September 1999 |volume=64 |issue=5 |pages=580–589 |doi=10.1002/(SICI)1097-0290(19990905)64:5<580::AID-BIT8>3.0.CO;2-X |pmid=10404238 }}</ref> skeletal muscle tissue,<ref>{{cite journal |last1=Heher |first1=Philipp |last2=Maleiner |first2=Babette |last3=Prüller |first3=Johanna |last4=Teuschl |first4=Andreas Herbert |last5=Kollmitzer |first5=Josef |last6=Monforte |first6=Xavier |last7=Wolbank |first7=Susanne |last8=Redl |first8=Heinz |last9=Rünzler |first9=Dominik |last10=Fuchs |first10=Christiane |title=A novel bioreactor for the generation of highly aligned 3D skeletal muscle-like constructs through orientation of fibrin via application of static strain |journal=Acta Biomaterialia |date=September 2015 |volume=24 |pages=251–265 |doi=10.1016/j.actbio.2015.06.033 |pmid=26141153 }}</ref> ligaments, cancer tissue models, and others. Currently, scaling production of these specialized bioreactors for industrial use remains challenging and is an active area of research.

For more information on artificial tissue culture, see [[tissue engineering]].