Amin et al. 2015; Ramanan et al. 2016; Mayali 2018). Also, bacterial extracellular
polymeric substances can protect algae from toxic compounds such as heavy metals
(Decho and Gutierrez 2017). Other metabolites can be exchanged within the algae–
bacteria consortium. Bacterial vitamin B1 and B12 may enhance the microalgae
growth (Croft et al. 2005; Helliwell 2017), and phytohormones have positive effect
on lipid accumulation in algae (Bruhn et al. 2007; Amin et al. 2009; Seyedsayamdost
et al. 2011; Wahl et al. 2012; Danchin and Braham 2017). Moreover, algal exudates
represent a carbon source for bacteria. However, hydrocarbons of different origin,
accumulated from external source (oil-polluted areas) or produced by algae may be
trapped within the phycosphere. In the latter case, the role of hydrocarbons in algae
includes water balance, self-defense, signaling, and membrane architecture (Binark
et al. 2000).
7.4.2 Algae–Bacteria Synergy Within Phycosphere in Oil
Pollution Conditions
Amin and coauthors (2015) evaluated the positive effect of coastal diatom Pseudonitzschia multiseries–bacteria interaction on the diatom growth. They hypothesized
that hydrocarbons-degrading bacteria associated to the diatom (Alcanivorax,
Marinobacter, Pseudoalteromonas, Thalassospira) produce auxin phytohormone
indole-3 acetic acid that stimulates algal growth. Accordingly, Hedlund et al.
(2001) have demonstrated the role of Marinobacter dioxygenase (involved in
polycyclic aromatic hydrocarbons degradation) in the indole-3 acetic acid
production.
Additionally, associated bacteria serve as helper for their hosts during environmental perturbation such as changing salinity (Xie et al. 2013; Dittami et al. 2016).
For instance, Picochlorum sp., a green alga can survive in a wide range of salinity
(from 0.35% to 10.8%) (Wang and Shao 2014); Foflonker and coauthors (2014)
have shown that the genome of this algal strain harbors 24 additional genes derived
from bacteria that are responsible for the response to saline stress.
Moreover, Lea-Smith et al. (2015) assessed alkane and alkene production capacity by cyanobacteria Prochlorococcus and Synechococcus. Derivatives of phytol,
such as pristane and phytane produced by algae and utilized as biomarkers for
monitoring hydrocarbonsbiodegradation, can even be degraded by some
hydrocarbonoclastic bacterial taxa (e.g., pseudomonads) (Rontani et al. 1999;
Dawson et al. 2013). Likewise, benzokinones and naphthoquinones (isoprenoids),
produced and utilized by algae during photosynthesis and respiration, have a structure whose skeleton consists of hydrocarbons (Nowicka and Kruk 2010); strains
belonging to the genus Shewanella can use isoprenoids as electron acceptors during
the degradation of humic acids (Newman and Kolter 2000). Moreover, McGenity
et al. (2012) hypothesized that similar compounds, isoprene by algae, could have a
role in feeding specialist hydrocarbon-degrading bacteria because of their restricted
7 Biodegradation of Hydrocarbons in Marine Environment
211
polymeric substances can protect algae from toxic compounds such as heavy metals
(Decho and Gutierrez 2017). Other metabolites can be exchanged within the algae–
bacteria consortium. Bacterial vitamin B1 and B12 may enhance the microalgae
growth (Croft et al. 2005; Helliwell 2017), and phytohormones have positive effect
on lipid accumulation in algae (Bruhn et al. 2007; Amin et al. 2009; Seyedsayamdost
et al. 2011; Wahl et al. 2012; Danchin and Braham 2017). Moreover, algal exudates
represent a carbon source for bacteria. However, hydrocarbons of different origin,
accumulated from external source (oil-polluted areas) or produced by algae may be
trapped within the phycosphere. In the latter case, the role of hydrocarbons in algae
includes water balance, self-defense, signaling, and membrane architecture (Binark
et al. 2000).
7.4.2 Algae–Bacteria Synergy Within Phycosphere in Oil
Pollution Conditions
Amin and coauthors (2015) evaluated the positive effect of coastal diatom Pseudonitzschia multiseries–bacteria interaction on the diatom growth. They hypothesized
that hydrocarbons-degrading bacteria associated to the diatom (Alcanivorax,
Marinobacter, Pseudoalteromonas, Thalassospira) produce auxin phytohormone
indole-3 acetic acid that stimulates algal growth. Accordingly, Hedlund et al.
(2001) have demonstrated the role of Marinobacter dioxygenase (involved in
polycyclic aromatic hydrocarbons degradation) in the indole-3 acetic acid
production.
Additionally, associated bacteria serve as helper for their hosts during environmental perturbation such as changing salinity (Xie et al. 2013; Dittami et al. 2016).
For instance, Picochlorum sp., a green alga can survive in a wide range of salinity
(from 0.35% to 10.8%) (Wang and Shao 2014); Foflonker and coauthors (2014)
have shown that the genome of this algal strain harbors 24 additional genes derived
from bacteria that are responsible for the response to saline stress.
Moreover, Lea-Smith et al. (2015) assessed alkane and alkene production capacity by cyanobacteria Prochlorococcus and Synechococcus. Derivatives of phytol,
such as pristane and phytane produced by algae and utilized as biomarkers for
monitoring hydrocarbonsbiodegradation, can even be degraded by some
hydrocarbonoclastic bacterial taxa (e.g., pseudomonads) (Rontani et al. 1999;
Dawson et al. 2013). Likewise, benzokinones and naphthoquinones (isoprenoids),
produced and utilized by algae during photosynthesis and respiration, have a structure whose skeleton consists of hydrocarbons (Nowicka and Kruk 2010); strains
belonging to the genus Shewanella can use isoprenoids as electron acceptors during
the degradation of humic acids (Newman and Kolter 2000). Moreover, McGenity
et al. (2012) hypothesized that similar compounds, isoprene by algae, could have a
role in feeding specialist hydrocarbon-degrading bacteria because of their restricted
7 Biodegradation of Hydrocarbons in Marine Environment
211