Environmental Science - Essay Example

s Article:Promotion of arsenic phytoextraction efficiency in the fern Pteris vittata by the inoculation of As-resistant bacteria: a soil bioremediation perspective Author: Lampis,S et al.Publication: Frontiers in Plant ScienceDate: 2015 Feb 18Arsenic, is one of the major pollutants that has contaminated soil and drinking water. Even though it exists naturally in the crust most of the arsenic found today have been produced due to anthropogenic activities.

Arsenic is a known toxic chemical which can induce toxicity at the genetic level. It is also a well known carcinogen. It causes several physiological problems even with acute exposure and therefore the presence of arsenic in the atmosphere is a potential threat to the health of humans. Researchers have long searched for appropriate methodologies to make the environment arsenic free and phytoremediation is considered one of the most efficient and cost effective ways to remove arsenic from arsenic contaminated soil.

In this paper, Lampis et al, test the efficiency of a fern Pteris vittata inoculated with certain bacterial strains, on arsenic phytoextraction in an arsenic contaminated soil.The researchers aimed to investigate the capability of Pteris vittata or Chinese brake fern to remove arsenic from an arsenic contaminated soil sample when inoculated with certain bacterial strains. The soil sample sued for the study was procured from an arsenic contaminated area in in Scarlino Industrial area in Tuscany, Italy.

This particular site served as a landfill area where almost 1.5milion tons of arsenopyrite cinders had been dumped thereby exposing the dump site to rain and subsequent leaching of the arsenic into the soil to the groundwater table. The researchers procured the rhizosphere of different autochthonous plants that grew in and around the Scarlino area and used the plant parts to extract bacterial strains that were naturally arsenic-resistant. They cultured the bacterial strain under laboratory conditions to obtain pure colonies.

The ability of the bacteria to promote plant growth was also checked by conducting assay for IAA production and measuring the 1-amino-cyclopropane-1-carboxylic acid (ACC) deaminase activity. Taxonomic analysis of the bacterial isolates was conducted using both wet lab and dry lab methods.Next, the reserachers propagated the growth of Chinese brake fern under controlled conditions. Prior to this the arsenic content in the soil was measured. Four experimental set ups were done-i) Non-inoculated plants, ii) Plants inoculated with the siderophore-producing and arsenate-reducing bacteria Pseudomonas sp.

P1III2 and Delftia sp. P2III5 (A); iii) Plants inoculated with the siderophore and indoleacetic acid-producing bacteria Bacillus sp. MPV12, Variovorax sp. P4III4, andPseudoxanthomonas sp. P4V6 (B)iv) Plants inoculated with all five bacterial strains - Pseudomonas sp. P1III2 ,Delftia sp, Bacillus sp. MPV12, Variovorax sp. P4III4, and Pseudoxanthomonas sp.The researchers, at the end of the experiment, measured the biomass and the arsenic level in the roots as well as the fronds of the ferns.

The results showed that there was a significant increase of almost 35% in the biomass of the plants which had been inoculated with bacteria when compared to those that had not received inoculation. The test results also confirmed that plants that received mixed inoculum had a greater capability to phytoextract arsenic from the soil as compared to non-inoculated ferns. Non-inoculated ferns could extract 13% arsenic while fern inoculated with bacteria could easily phytoextract up to 35% of soil arsenic.

The researchers further established that the bacterial strains also induced greater production of plant growth hormones which helped the plants to grow. Thus, it was established that ferns with a natural capability to phytoextract arsenic from the soil could extract greater amount of arsenic when inoculated with arsenic-resisting bacteria.Arsenic is a major pollutant in many areas of the world. Ferns have been employed for phytoremediation. However, this experiment helped understand the fact that the efficiency of phytoremediation of the plants could be increased by using certain microorganisms.

In the future, the same application may be investigated on phytoremediation of other heavy metals as well.The method of phytoremediation is today extremely important since it poses no threat to the environment and helps in reclamation of soil and water.