Bacteria that reduces noxious effect of arsenic identified
An assessment of soil samples identified a bacteria known as Propionibacterium avium strain P29, a native Colombian microorganism which could reduce the negative impact of arsenic.Bogotá D. C., 04 de agosto de 2016 — Agencia de Noticias UN-
Using bacteria to precipitate arsenic is not new. The challenge is to identify native Colombian bacteria.
The P29 bacterium has the capability to convert sulfate into sulphur which then reacts with arsenic forming arsenic sulphur. Biologically remedying (bioremediation) this toxic element which is present in activities such as mining and agriculture and that also can become carcinogenic.
The experiments were carried out with isolated microorganisms from different kinds of crops of up to 14 years of age, including asparagus, onion and zucchini. They confirmed that the P29 bacteria had better performance, resisting a minimum inhibitory concentration of up to 100 parts per million (PPM) of arsenic. In other words, this was the growth limiting level of the microorganism per concentration of this element.
According to the Biodiversity Information System, Colombia has around 10% of the world’s known animal and plant species; it has 56,455 species represented in 7,432 vertebrates, 15,269 invertebrates (of 300,000 which may exist), 30,436 plants, 1,674 lichens and 1,644 fungi.
However a group of biochemistry researchers headed by Universidad Nacional de Colombia (UNal) Microbiologist and Professor Pedro F. de Brito Brandão is currently studying native microorganisms to assess their biotechnological potential in agriculture, industry and the environment.
“When we applied sulphate-reducing bacteria, specifically strain P29, we observed that rice seedlings grew better, inclusively with arsenic in the soil, which is what impedes their growth. We also need to continue testing to obtain more convincing results,” said Brito.
Through biochemical and chemical processes, Strain P29 has a bearing on arsenic transformation to arsenic sulphur, making this metalloid less bio-available in the environment.
Its presence naturally could be because it is trapped in rocks (by mining) and also by applying pesticides or herbicides.
After gathering soil samples the researchers identified and isolated microorganisms in the laboratory. For this they incubated the samples in anaerobic (oxygen deprived) conditions.
Furthermore they initially isolated 10 bacteria resistant to arsenic in different arsenic concentrations and finally arrived to the best: Propionibacterium avium.
Two native sulphate-reducing bacteria obtained by researchers from another university and used as control showed a performance similar to P29 in precipitation tests, but they continue to be evaluated.
During the metabolic process of the P29, to transform sulfate into sulphur, the bacterium is enriched with a source of carbon (as lactate) and transforms it into pyruvate.
In this transformation electrons are released, which through electronic transport sends it to a receptor, in this case agricultural sulphate. And once the latter receives the electrons, the presence of environmental hydrogen produces a biochemical reaction and converts into sulphur (H2S).
While H2S is also a toxic substance, the idea is to neutralize arsenic mobility, which is even a more toxic metalloid due to formation of arsenic sulphur. This is metalloid bioremediation.
These findings advance towards diminishing pollution, both on agricultural land as well as in plants which directly impact food safety and the negative impact of mining on health.(Por: Fin/HEVC/DMH/APBL