There are two competing methods, as far as I see: use the bacteria themselves to digest plastic, or use extract the enzyme responsible for plastic dissolution and manufacture it the enzyme responsible for plastic dissolution.

1. Bacteria:

  - Can they adapt to the climate and the ecology of their target environment? 
  - Can they adapt, in particular, to oceanic salt water to dissolve dumped plastic waste? 
  - Overpopulation: what are the consequences? Do natural predators of this bacteria exist? 
  - Underpopulation: can the bacteria be genetically modified to survive in landfills or oceans? Must they be isolated in a controlled environment with plastic?

2. Manufacturing

  - If the enzyme/manufacturing process is controlled by a profit-seeking corporation, would this mean unequal pollution capabilities between the developed and developing worlds? I suspect more plastic waste is improperly disposed by developing countries - thus further exacerbating the problem. 
  - Must the bacteria manufacture the enzyme necessary, or can an enzyme be chemically manufactured? 
  - Does the enzyme have an optimal/useful operating temperature? The Amazon rainforest is not only a freshwater environment, but also a relatively warm climate. Our waste may be captured by cold ocean currents or be present in countries simply far too distant from the equator for this to be a feasible option.

3. Process consequences

  -What are the products of plastic dissolution by this bacteria? 
  -If the process is performed inefficiently/incompletely due to some environmental factors (water salinity, pH, temperature), are there any harmful byproducts? 
  -If the process produces simple chemicals - do these harm other organisms in the environment surrounding the bacteria? 
  -Would the accumulation of the products (CO2 gas for example) further global warming or pollution?

This article leaves me yearning for more details.