128
L. Schorr et al.
and can be auspicious chassis sources for designers, interested in reducing N overloads in WWTPs and soils. Anammox bacteria produce less sewage sludge, are thus
costs lowering and promising candidates for reducing in the various environments
NH
+
4 , NO
−
3 , and NO
−
2 when skilled constructed with synthetic biological techniques
[55, 94, 95, 101].
6 Future Perspectives
Synthetic biology is a logical extension of what is known as recombinant DNA
(rDNA) technology or genetic engineering, that progresses continuously since the
1970s [57, 91]. Promising microorganisms for N concerned sustainable biotechnologies are also cyanobacteria, requiring a radical re-engineering with synthetic
biology techniques to unlock their application potential [85]. Increasingly available devices for modifying cyanobacteria and their metabolic strategies include
design advances concerning genetic promoters, ribosome binding sites, riboswitches,
reporter proteins, modular vector systems, and markerless selection systems. Using
new toolkits, cyanobacteria have been successfully engineered and express heterologous pathways for the production of a wide variety of valuable compounds [85].
For developing accurate predicting models for the best possible integration of pathways into the larger cellular metabolic network, in real-world applications afford the
refinement of genetic circuits used for expressing heterologous pathways. However,
it is obvious that despite the progress in synthetic biology and metabolic engineering
in the last years, further improvements are required to make cyanobacteria fit and
competitive for survival among heterotrophic microorganisms.
For a better N conversion performance, an improved elimination of surplus nitrate
would be beneficial, when an engineered nitrifying and denitrifying chassis additionally possesses the capability to form a biofilm surrounded with extra polymeric
substances (EPS) and structured with tubular pores, as the nitrifying bacterium N.
europaea and the denitrifying bacterium P. denitrificans are demonstrating [35, 59].
Similar shaped as biofilms with tubular pore structures are sewage flocs, which ensure
aerobic conditions in the outer region and anaerobic inside zones and work as a microbial fuel cell (MFC; Fig. 8). Sewage flocs help circumventing stress and synthetic
biology tries combining the multicellular nitrifying and denitrifying potential of a
sewage floc in one bacterium chassis. It is thereby of interest that the newly modelled
chassis, integrated into a sewage floc, functions and exchanges its genetic support
components and resources within the polymeric, compartmentalized, tubular sewage
floc structure [100]. Such nitrification and denitrification combining cells could also
be used as a MFC to generate electricity asides removing nitrate and nitrite. This
idea has attracted much attention [66, 85, 122, 124]. A higher voltage in the cathode
chamber is achieved by heterotrophic denitrifying MFC bacteria when dissolved
oxygen in the surrounding high ammonia concentrated wastewater is high, between
3.0 and 4.2 mg/L, whereas total nitrogen (TN) removal is favoured at low dissolved
oxygen levels (0.5–1.0 mg/L) [124]. Electrochemically active bacteria generate an
L. Schorr et al.
and can be auspicious chassis sources for designers, interested in reducing N overloads in WWTPs and soils. Anammox bacteria produce less sewage sludge, are thus
costs lowering and promising candidates for reducing in the various environments
NH
+
4 , NO
−
3 , and NO
−
2 when skilled constructed with synthetic biological techniques
[55, 94, 95, 101].
6 Future Perspectives
Synthetic biology is a logical extension of what is known as recombinant DNA
(rDNA) technology or genetic engineering, that progresses continuously since the
1970s [57, 91]. Promising microorganisms for N concerned sustainable biotechnologies are also cyanobacteria, requiring a radical re-engineering with synthetic
biology techniques to unlock their application potential [85]. Increasingly available devices for modifying cyanobacteria and their metabolic strategies include
design advances concerning genetic promoters, ribosome binding sites, riboswitches,
reporter proteins, modular vector systems, and markerless selection systems. Using
new toolkits, cyanobacteria have been successfully engineered and express heterologous pathways for the production of a wide variety of valuable compounds [85].
For developing accurate predicting models for the best possible integration of pathways into the larger cellular metabolic network, in real-world applications afford the
refinement of genetic circuits used for expressing heterologous pathways. However,
it is obvious that despite the progress in synthetic biology and metabolic engineering
in the last years, further improvements are required to make cyanobacteria fit and
competitive for survival among heterotrophic microorganisms.
For a better N conversion performance, an improved elimination of surplus nitrate
would be beneficial, when an engineered nitrifying and denitrifying chassis additionally possesses the capability to form a biofilm surrounded with extra polymeric
substances (EPS) and structured with tubular pores, as the nitrifying bacterium N.
europaea and the denitrifying bacterium P. denitrificans are demonstrating [35, 59].
Similar shaped as biofilms with tubular pore structures are sewage flocs, which ensure
aerobic conditions in the outer region and anaerobic inside zones and work as a microbial fuel cell (MFC; Fig. 8). Sewage flocs help circumventing stress and synthetic
biology tries combining the multicellular nitrifying and denitrifying potential of a
sewage floc in one bacterium chassis. It is thereby of interest that the newly modelled
chassis, integrated into a sewage floc, functions and exchanges its genetic support
components and resources within the polymeric, compartmentalized, tubular sewage
floc structure [100]. Such nitrification and denitrification combining cells could also
be used as a MFC to generate electricity asides removing nitrate and nitrite. This
idea has attracted much attention [66, 85, 122, 124]. A higher voltage in the cathode
chamber is achieved by heterotrophic denitrifying MFC bacteria when dissolved
oxygen in the surrounding high ammonia concentrated wastewater is high, between
3.0 and 4.2 mg/L, whereas total nitrogen (TN) removal is favoured at low dissolved
oxygen levels (0.5–1.0 mg/L) [124]. Electrochemically active bacteria generate an