“Super bac­teria” clean­ing up after oil spills

We all know that mar­ine bac­teria can assist in clean­ing up after oil spills. What is sur­pris­ing is that giv­en the right kind of encour­age­ment, they can be even more effect­ive. ​“We know that oil spills hap­pen – and that they will hap­pen again”, says Roman Net­zer, a research­er and bio­lo­gist at SIN­TEF. ​“We also know that this can have a major neg­at­ive impact on the nat­ur­al envir­on­ment. This is why we’ve been study­ing a series of chem­ic­al and bio­lo­gic­al ana­lyt­ic­al tech­niques to assess the levels of ser­i­ous­ness of oil spills. We also wanted to find out wheth­er so-called biore­medi­ation rep­res­ents an effect­ive approach to clean­ing up after such acci­dents”, he explains. Biore­medi­ation is nature’s way of clean­ing up. Plants, bac­teri­al decom­posers or enzymes are used to remove con­tam­in­ants and restore the bal­ance of nature in the wake of pol­lu­tion incid­ents.

Tool box

When we clean up after an oil spill of a giv­en size, such as along our shorelines, we start by apply­ing mech­an­ic­al meth­ods using spades and brooms, com­bined with chem­ic­als. How­ever, we should­n’t deceive ourselves, even when the worst of the spill has been cleared away. The sur­face usu­ally con­ceals oil bur­ied deep­er in the sed­i­ment. ​“It is here that bio­lo­gic­al, or biore­medi­ation, meth­ods, come into their own”, says Net­zer. ​“This approach can make clean­ing up oper­a­tions even more thor­ough, and cost-effect­ive. We wanted to find out what works – and how. And not least to gath­er data that can be used to sup­port decision-mak­ing pro­cesses in situ­ations where nature needs that little extra help” he explains. So the research­ers set up a num­ber of exper­i­ments in the mar­ine labor­at­ory. Their aim was to look into how the micro­scop­ic res­id­ents of the oceans, such as bac­teria and oth­er microbes, can assist us in clean­ing up pol­lut­ants, and wheth­er they are cap­able of restor­ing the nat­ur­al bal­ance after­wards. And not least, to determ­ine the lim­it­ing factors involved in this pro­cess. It was only after they had failed to achieve any sig­ni­fic­ant response from their ini­tial exper­i­ments, caus­ing them to change the exper­i­ment­al para­met­ers, that their sen­sa­tion­al res­ults emerged.

Imit­at­ing nature along the shoreline

Here at Brat­tørkaia in Trond­heim, research­ers have assembled a com­pre­hens­ive ​“oil lib­rary” which they use in this type of research. The prop­er­ties of the oils have been accur­ately meas­ured and recor­ded, and this enabled the research­ers to select the per­fect oil for their exper­i­ment. ​“The oil we chose is pro­duced in large volumes on the Nor­we­gi­an shelf, and is thus ideal for sim­u­lat­ing a real­ist­ic scen­ario involving the accu­mu­la­tion of oil on a Nor­we­gi­an shoreline”, explains Net­zer. ​“We then tried to sim­u­late what hap­pens in nature when oil becomes stran­ded”, he says. Six­teen tanks were filled with sed­i­ments, togeth­er with nat­ur­ally-occur­ring bac­teri­al flora, oil and sea­wa­ter. The research­ers also sim­u­lated the action of the tides by repla­cing the sea­wa­ter and thus ensur­ing that there was an adequate sup­ply of oxy­gen and nutri­ents. What then happened in the tanks was care­fully recor­ded. But after a month of obser­va­tions, only minor amounts of con­tam­in­ants had been removed.

Bio­lo­gic­al ana­lyses the most sensitive

Chem­ic­al and bio­lo­gic­al ana­lyses car­ried out after­wards pro­duced approx­im­ately the same res­ults. ​“How­ever, we noted that the bio­lo­gic­al approaches, which ana­lyse the con­cen­tra­tions of bac­teria, their DNA, and oxy­gen con­sump­tion, were very sens­it­ive and provided us with a great deal of inform­a­tion. Chem­ic­al approaches have to be very advanced in order to achieve the same detec­tion thresholds” says Net­zer. ​“Even the res­ults of the bac­teri­al exper­i­ments were obvi­ously dis­ap­point­ing”, he explains. ​“But the bio­lo­gic­al res­ults indic­ated that we were on the right track, and this gave us the idea to give nature a help­ing hand. We already knew that the bac­teria would repro­duce – and thus be more effect­ive in their work – if they were provided with addi­tion­al nutri­ents. In nature, bac­teria flour­ish best in the pres­ence of high con­cen­tra­tions of phos­phates and nitro­gen”, says Net­zer. The prob­lem is that the nat­ur­al con­cen­tra­tions of these sub­stances are insuf­fi­cient”, he says. So the research­ers decided to give them a little sup­ple­ment. They also increased the water tem­per­at­ure, reduced the oxy­gen con­cen­tra­tion and exten­ded the dur­a­tion of the exper­i­ment. The tid­al regime was also adjus­ted, so that now there was a 12-hour inter­val (instead of the pre­vi­ous 3) between the intro­duc­tion of new water to the tanks. And this pro­duced res­ults! After one month, the research­ers got their clear and unam­bigu­ous answers. Ana­lyses revealed that the extra nutri­ents had enabled the bac­teria to work more effect­ively in break­ing down the oil. At the same time, the increase in tem­per­at­ure, reduced oxy­gen con­cen­tra­tion and adjust­ment of the tid­al cycle pro­duced no sig­ni­fic­ant effect. ​“We think that the data obtained from these exper­i­ments will be of con­sid­er­able import­ance to the oil com­pan­ies – not least because they are now expand­ing their activ­it­ies into envir­on­ment­ally-sens­it­ive areas in and around the Bar­ents Sea”, says Net­zer. He now envis­ages the intro­duc­tion of a new weapon in the battle to clean up after oil spills. ​“We believe that in time we will be able to make cap­sules which can attach them­selves to rocks along the shoreline. These will provide the bac­teria with ideal grow­ing con­di­tions by releas­ing nutri­ents as and when needed”, says Net­zer.

Facts:

The ​“Pet­ro­bi­or­em” pro­ject has been to devel­op a tool box of ana­lyt­ic­al approaches from which to select the best meth­od of clean­ing up after oil spills. It will also facil­it­ate assess­ments of ​“envir­on­ment­al status” fol­low­ing clean-up oper­a­tions. It is a stra­tegic SIN­TEF-fun­ded pro­ject last­ing 15 months. Research­ers from two depart­ments – Envir­on­ment­al Tech­no­logy and Bio­tech­no­logy and Nanomedi­cine – are work­ing togeth­er to assemble a tool­box of optim­al ana­lyt­ic­al approaches. These will provide decision-makers in the oil and gas industry and the Nor­we­gi­an Coastal Admin­is­tra­tion with assist­ance in con­nec­tion with oil dis­charge policies. In the next phase the research­ers will test the tool box using pre-defined scen­ari­os of spe­cial interest to the oil industry. In the future, they plan to carry out sev­er­al stud­ies in which they will vary para­met­ers such as tem­per­at­ure, oil type, nutri­ent con­cen­tra­tions, etc., as a basis for design­ing biore­medi­ation strategies fol­low­ing oil dis­charges. They also intend to work togeth­er with research­ers in the field of poly­mer chem­istry with the aim of devel­op­ing bio­lo­gic­al cap­sules con­tain­ing nutri­ents which can attach them­selves to the oil and release nutri­ents over a pro­longed peri­od.

The ​“tools” and the ​“oil lib­rary” at SINTEF:

The ​“tool box” is inten­ded primar­ily for the ana­lys­is of biore­medi­ation pro­cesses along shorelines in the wake of oil pol­lu­tion incid­ents. It will provide decision-makers with vital inform­a­tion as to wheth­er this type of clean-up approach is neces­sary, recom­mend­a­tions as to the meth­od which should be applied, and a meas­ure of wheth­er the nat­ur­al envir­on­ment­al bal­ance has been restored fol­low­ing the oil spill. How­ever, it will also be pos­sible to apply this approach to study remedi­ation pro­cesses linked to oth­er types of pol­lu­tion such as that caused by heavy metals or chem­ic­als in oth­er set­tings such as land­fill sites, forestry or indus­tri­al facil­it­ies. The chem­ic­al ana­lyt­ic­al equip­ment used in this pro­ject is cap­able of ana­lys­ing thou­sands of oil com­pon­ents. Research­ers will apply DNA sequen­cing tech­no­lo­gies to identi­fy the hun­dreds of dif­fer­ent bac­teria present in each sed­i­ment sample. How­ever, not all inform­a­tion is equally rel­ev­ant. In order to pro­cess the vast amounts of data involved, and extract only what is rel­ev­ant, the research­ers are using advanced stat­ist­ic­al meth­ods such as mul­tivari­ate and prin­cip­al com­pon­ent ana­lys­is to help them arrive at their key con­clu­sions. The micro­bi­al decom­pos­i­tion of oil along shorelines is influ­enced by many phys­ic­al, chem­ic­al and bio­lo­gic­al factors. Para­met­ers such as tem­per­at­ure, access to nutri­ents, oxy­gen con­cen­tra­tion, the micro­bi­al com­munity in ques­tion and, not least, the chem­ic­al com­pos­i­tion of the oil, all influ­ence the pro­cess. Oil is com­posed of a mul­ti­tude of dif­fer­ent com­pon­ents. While some of these are rel­at­ively easy for microor­gan­isms to break down, oth­ers are more dif­fi­cult. The com­pos­i­tion of the oil is thus a key factor in assess­ing its poten­tial decom­pos­i­tion by bio­lo­gic­al pro­cesses. SIN­TEF has been work­ing for sev­er­al dec­ades to determ­ine the chem­ic­al com­pos­i­tion and phys­ic­al prop­er­ties of the major­ity of oils encountered on the Nor­we­gi­an shelf. This data­base is a poten­tial found­a­tion for a vari­ety of stud­ies con­trib­ut­ing to improve emer­gency pre­pared­ness linked to indi­vidu­al fields. This ​“oil lib­rary” is quite unique, and of major sig­ni­fic­ance in the field of oil research. Source: SIN­TEF (Stif­telsen for indus­tri­ell og teknisk for­skning), by Christina Benjaminsen