Requirements for sulfur in cell density‐independent induction of luminescence in Vibrio fischeri under nutrient‐starved conditions

Abstract

Despite the universal requirement for sulfur in living organisms, it is not known whether the luminescence of Vibrio fischeri is sulfur-dependent and how sulfur affects the intensity of its luminescence. In this study, we investigated the requirement for sulfur in V. fischeri luminescence under nutrient-starved conditions. Full induction of V. fischeri luminescence required MgSO(4); in artificial seawater cultures that lacked sufficient MgSO(4), its luminescence was not fully induced. This induction of luminescence was not dependent on autoinduction because the cell density of V. fischeri did not reach the critical threshold concentration. In addition to MgSO(4), this cell density-independent luminescence was induced or maintained by nontoxic concentrations of l-cysteine, sulfate, sulfite, and thiosulfate. Moreover, the addition of N -3-oxo-hexanoyl homoserine lactone and N -octanoyl homoserine lactone, which are known autoinducers in V. fischeri, did not induce luminescence under these conditions. This result suggested that the underlying mechanism of luminescence may be different from the known autoinduction mechanism.

Influence of cations and anions on the induction of cell density‐independent luminescence in Photorhabdus luminescens

“…Some studies have shown that cell density‐independent luminescence can be regulated by various factors, such as heat shock proteins , UV irradiation , osmolarity , and redox state . In addition, we recently demonstrated the induction of cell density‐independent luminescence in V. fischeri by the addition of sulfur compounds , which was enhanced by the addition of potassium, bicarbonate, and magnesium . Similarly, in the present study, cell density‐independent luminescence of P. luminescens was induced by the addition of potassium, bicarbonate, and magnesium (Figs.…”

“…In addition to these autoinducer‐mediated regulatory mechanisms, we recently demonstrated that the regulation of V. fischeri luminescence in artificial seawater containing NaCl, KCl, MgCl 2 , CaCl 2 , NaHCO 3 , and MgSO 4 was independent of cell density . Moreover, we showed that induction of this type of luminescence required the addition of sulfur‐containing compounds, including sulfate and L‐cysteine , which was enhanced by the addition of potassium, bicarbonate, and magnesium . However, it remains unclear whether the ion composition of the culture medium affects the induction of luminescence in non‐marine luminescent P. luminescens bacteria.…”

Interactions between bicarbonate, potassium, and magnesium, and sulfur‐dependent induction of luminescence in Vibrio fischeri

“…V. fischeri (ATCC 49387) was obtained from the American Type Culture Collection and grown in 100 ml of nutrient broth (NB) (Becton, Dickinson) supplemented with 3% NaCl in 300 ml flasks, which were agitated on a shaker at 70 rpm at 22 °C. V. fischeri was also cultured at 22 °C in artificial seawater (ASW) [16,17], which was composed of 28.1 g/l of NaCl, 0.77 g/l of KCl, 1.21 g/l of CaCl 2 , 4.8 g/l of MgCl 2 ⋅ 6 H 2 O, 0.11 g/l of NaHCO 3 , and 3.5 g/l of MgSO 4 ⋅ 7 H 2 O. Bacterial proliferation was monitored by measuring the increase in optical density of the culture suspension at 600 nm (OD 600 ).…”

“…At a low cell density, V. fischeri produces very little luciferase and luminescence, whereas at a higher cell density, these levels are increased. This cell density-dependent induction of luciferase synthesis and resultant luminescence is controlled by diffusible luminescence inducing factors called autoinducers, 17]. In particular, this luminescence type was induced both by inorganic sulfur sources, such as sulfate, sulfite, and thiosulfate, and by organic sulfur sources, including L-cysteine and L-cystine, but not by the addition of autoinducers, such as 3-oxo-C6-HSL or C8-HSL [17].…”

Selenium cannot substitute for sulfur in cell density‐independent bioluminescence in Vibrio fischeri

“…In contrast to cell density‐dependent luminescence, we recently discovered cell density‐independent luminescence in V. fischeri induced under nutrient‐starved conditions . Moreover, we demonstrated the induction of this type of luminescence by the addition of sulfur‐containing compounds , which was enhanced by the addition of potassium, bicarbonate, and magnesium . This type of luminescence was induced by both inorganic sulfur sources, e.g., sulfate, sulfite, and thiosulfate, and by organic sulfur sources, including L‐cysteine and L‐cystine .…”