Versatile Microbial Mats for Remediation of Hazardous Contaminants

The Biomats^® constructed microbial mats (MATS)

BioMat is a "constructed microbial mat of biological organisms that self-associate to form a complex ecosystem capable of removing contaminants from the environment. The constructed microbial mat comprises cyanobacteria and purple autotrophic bacteria and other microorganisms organized into a layered structure which is held together with slime, and has an organic nutrient source provided." Like the other active microbial systems the biomat is able to simultaneously sequester heavy metals and degrade organic contaminants. The overall oxygen concentration in the system can be controlled by manipulation of the activity of oxygen producing phototrophic bacteria using lighting intensity. Together with different metabolic zones (micro-environments) within the mat a variety of bioremediation reactions are enabled, like anoxic bioreduction of metals (e.g. Cr(VI) to Cr(III), Se(IV or VI) to Se(0)), metabolism of perchlorate and explosives, sequestration and metabolism of petrochemicals, dechlorination of trichlorethylene, or nitrification under highly oxic conditions.

Microbial Aquatic Treatment Systems (MATS) has tested the biomats at pilot level, applying the following treatment designs (Patent US6033559):
• Floating mats on ponds: with low-flow or batch mode large volumes of water can be treated economically (e.g. removal of manganese from acid coal mine drainage).
• Dry mat used as biosorbents for removal of organics and metals from water.
• Mats immobilized as biofilms on vertical boards have been tested for the final polishing treatment of radioactive water.
• Mat microbes have also been immobilised in silica particles and tested for the removal of a menu of radionuclides, including plutonium and uranium. With the words of a co-inventor of biomats, "this immobilization represents an important advance of the technology in terms of the rates of removal and ease of engineering and management.

The distinguishing feature and advantage of biomats compared with all other systems using active microorganisms is the integration of photosynthetic bacteria into the microbial consortium, creating a self-sustainable system with minimal need for supplemental nutrition.

PLANTECO Environmental Consultants LLC collaborates with the Biomats^® inventors, Bender, J.A. and Phillips, P.C. in the application of the versatile mats for water quality management, bioremediation, aquaculture, soil amendment, and energy production.

USES OF MATS: AN OVERVIEW
The mature microbial mat consortium is a durable microbial community that can be applied in a variety of uses related to agriculture, aquaculture, bioremediation of contaminants and energy production. The following summary lists actual and potential applications of mats.

Aqua culture:
(1) As a fish feed for tilapia, Oreochromis niloticus or Tilapia nilotica (Bender and Vatcharapijarn, 1989; Ekpo and Bender, 1989; Phillips et al., 1994a);
(2) Aquaculture filter, transforming nitrogenous fish wastes into benign products (Lee et al., 1996). The process related of rapidly sequestering ammonia from water is described by Goodroad et al. (1995).

Agriculture:
(1) Soil amendments, such as fertilization via nitrogen fixation (Rao and Burns, 1990a; 1990b; Paerl et al., 1991; Fernandez Valiente et al., 2000);
(2) Plant growth stimulators (Phillips and Bender, unpublished).

Bioremediation:
(1) Sequester of heavy metals (Bender et al., 1994a; Bender et al., 1994b; Bender et al., 1994c; Bender et al., 1995a; Bender et al., 1997; Mehrabi et al., in press; Phillips et al., 1994b; Phillips and Bender, 1995; Phillips et al., 1995; Phillips et al., 1996; Phillips and Bender, 1998; Phillips et al., 1999;
(2) Degradation of recalcitrant toxic organic contaminants (Bender et al., 1994d; Phillips et al., 1994c; Bender et al., 1995b; Phillips and Bender, 1995; Murray et al., 1997; O'Niell et al., 2000); (3) Removal of radionuclides (Bender et al., 2000).

Bioproduction:
(1) Biopolymers (Bender et al., 1994a);
(2) B12(Noparatnaraporn et al., 1986);
(3) Antibiotics (Fogg, 1971; Burgess et al., 1991);
(4) Antiviral substances (Hirotani et al., 1991);
(5) Substances showing toxicity against mouse leukemia cells have been reported by Nagumo et al., (1991).

Items (2)-(5) are products of the purple autotrophic group, a common resident of mats.

Short Videos of Microbial Mats
Click on the links below to view three short videos of the application and use of microbial mats:

1. Microbial Mat Bioreactor - This video shows a plate and shelf bioreactor set up in a greenhouse prior to use in a field project. Click here

2. Bioreactor Shelf - This video shows the inside of one of the bioreactor shelves. Microbial mat is shown growing on a synthetic fiber material in the shelf drawer. Click here

3. Removal of Uranium Using Microbial Mats - A short video showing removal of uranium from water using microbial mat immobilized on a silica bead matrix (developed by J. Bender and P. Phillips). Click here

 

 

 

 

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