Construction and initial characterization of a luminescentSynechococcussp. PCC 7942 Fe-dependent bioreporter

Abstract

A Synechococcus sp. PCC 7942 bioreporter strain capable of sensing bioavailable Fe was constructed by fusing the Fe-responsive isiAB promoter to the Vibrio harveyi luxAB genes. Monitoring luxAB-dependent luminescence through the growth curve demonstrated that in Fe-replete media, transcription from the isiAB promoter was induced transiently in the mid-exponential phase of growth. The initiation of transcription was the functional response to a 10-fold depletion of intracellular Fe to approximately 12 amol Fe per cell. Constitutive isiAB-dependent transcription was observed in Fe-depleted growth media. A dose-response relationship of the bioreporter was generated using trace metal-buffered Fraquil medium and was best represented by a sigmoidal curve having a linear component extending between pFe 21.1 (Fe3+=10(-21.1) M) and pFe 20.6 (Fe3+)=10(-20.6) M). Initial field trials conducted using water sampled from Lake Erie demonstrate that the bioreporter can serve as a quantitative tool to assess Fe deficiency in natural freshwater environments.

Construction of a self-luminescent cyanobacterial bioreporter that detects a broad range of bioavailable heavy metals in aquatic environments

“…We have calculated the calibration curves and subsequent LODs and dynamic ranges as a function of the free ion which is usually the most bioavailable and toxic metal species (Sunda and Lewis, 1978 ). This approach is not currently taken when calculating the dynamic ranges of heavy metal bioreporters (Magrisso et al, 2008 ) except for cyanobacterial iron bioreporters (Durham et al, 2002 ; Boyanapalli et al, 2007 ). The dynamic ranges calculated using this method show that the constructed cyanobacterial bioreporter varies in sensitivity with the different metals tested.…”

“…The real samples used reflect water matrices of different complexity (affected or not by anthropogenic influence). This approach is seldom used in the field of bacterial bioreporters (Magrisso et al, 2008 ; Hynninen and Virta, 2010 ) although, in the case of cyanobacteria, it has been done for iron bioreporters (Durham et al, 2002 ; Boyanapalli et al, 2007 ); P and N bioreporters (Munoz-Martin et al, 2011 , 2014a , b ) and for Co, Zn, and Ni bioreporters constructed by Peca et al ( 2008 ), using the coa and nrs detection systems. The concentrations of free ions detected by the bioreporter in the two river spiked samples represented an average of 68% of that predicted by chemical modeling and nearly 100% of that predicted in the spiked WWTP, which may be interpreted as the bioavailable fractions.…”

Genetically modified whole-cell bioreporters for environmental assessment

“…Synechococcus sp. strains PCC 7942 and PCC 7002 have been engineered to carry such reporter constructs, and the resulting bioreporters, designated as KAS101 (Durham et al, 2002) and CCMP2669 (Boyanapalli et al, 2007; Bullerjahn et al, 2010), respectively, have been used to assess Fe bioavailability in the Great Lakes (Hassler et al, 2009; McKay et al, 2005; Porta et al, 2005) and marine environments (Boyanapalli et al, 2007). These bioreporters function such that the bioluminescent response increases with reducing concentration of intracellular Fe 3+ , making them suitable for low concentration detection.…”

Cyanobacteria as Chassis for Industrial Biotechnology: Progress and Prospects

“…It is worth mentioning that most of the efforts for developing genetic engineering tools have been aimed at model or heavily studied cyanobacterial strains such as the filamentous, nitrogen-fixing Anabaena sp. strain PCC 7120 [31,32,33], and the naturally competent Synechococcus 7942 [34,35,36,37], Synechococcus 7002 [38,39,40,41,42,43,44] and Synechocystis 6803 [16,45,46,47,48,49,50,51,52]. This review discusses the recent developments in the field of cyanobacterial genetic modification in the past five years and how these tools can be employed to increase the efficiency of cyanobacteria in industrial biotechnology applications.…”