Microbially Derived Off-Flavor from Geosmin and 2-Methylisoborneol: Sources and Remediation - Reviews of Environmental Contamination and Toxicology - page 14

mutagen, precluding its use as an agrochemical, and none of the synthetic ana-
logues showed comparable activities to rutacridone epoxide (Meepagala et al. 2005).
Many Ruta species are sources of diverse classes of natural products with biological
activity including antifungal, phytotoxic, and antidotal (de Feo et al. 2002; Oliva et
al. 2003). Oliva et al. (2003) demonstrated the presence of fungicidal constituents
in the ethyl acetate extract of Ruta graveolens L. leaves against some agriculturally
important fungi.
Tellez et al. (2001b) screened F. cernua extracts against two species of cyano-
bacteria and one species of green algae to determine their potential as a selective
cyanobactericide. They found that the ether extract of F. cernua was selectively
inhibitory against the cyanobacterium responsible for the MIB induced off-flavor
associated with catfish farming operations.

D Lignocellulosic Agrowastes: Inexpensive Biosorbents

Activated carbon has been used very frequently for the removal of geosmin and MIB
from natural water (Hung and Lin 2006), raw water (Cook et al. 2001), and drinking
water (Hepplewhite et al. 2004; Elhadi et al. 2004; Liang et al. 2005). Nowack et al.
(2004) investigated methods for tailoring a commercial, lignite-based granular acti-
vated carbon to enhance its adsorption of MIB from natural water. Cook et al. (2001)
reported that powdered activated carbon (PAC) can effectively remove MIB and
geosmin when the correct dose is applied, especially where a higher dose is required
in the case of very turbid water. The high cost of activated carbon restricts its large-
scale use for abatement of these metabolites, and in recent years the search for low-
cost adsorbents has grown. By-products of lignocellulosic agroindustrial production
have been studied for potential use as inexpensive biosorbents (Ng et al. 2002a, b).
Barley straw inhibits the growth of cyanobacteria blooms (Barrett et al. 1996; Caffrey
and Monahan 1999; Ferrier et al. 2005), which has been attributed to the antialgal
activity of phenolics (tannins) present in the straw (Pillinger et al. 1994). Lignocellulosic
materials have the advantage of being readily available because the world's industry
utilizes less than 10% of raw material biomass from plantations (Pauli and Gravitis
1997). The remainder is waiting for effective utilization and could provide value-
added products. Many other applications for these residues are in the process of being
developed. Development of cost-effective and environment-friendly products from
agricultural wastes/by-products and plantations for the aquatic bioremedition of
brackishwater aquaculture is the objective of continued research of Central Institute
of Brackishwater Aquaculture, Chennai, India (Krishnani et al. 2002, 2003, 2004,
2005, 2006b, 2006c; Krishnani and Ayyappan 2006; Parimala et al. 2004, 2007).

E Bioremediation

Microbes metabolize a broad range of aquatic pollutants by complex enzyme-
catalyzed reactions. The genes encoding these proteins are localized on either large