Antimicrobial peptides (AMPs) have recently gained much attention because of their ability to overcome drug resistance and have emerged as a potential new class of antibacterial agents. These peptides are part of the innate immune system of all living organisms, including vertebrates, insects, bacteria and plants. AMPs encompass a number of different classes, including those that are rich in a particular amino acid. Important subsets are peptides rich in Arg and Trp residues that have broad and potent antimicrobial activity. These residues possess some crucial chemical properties that make them important components of antimicrobial peptides. Trp side chains are also implicated in peptide and protein folding in aqueous solution, where they contribute by maintaining native and nonnative hydrophobic contacts. This has been observed for the antimicrobial peptide from human lactoferrin, possibly restraining the peptide structure in a suitable conformation to interact with the bacterial membrane. These unique properties make the Arg- and Trp-rich antimicrobial peptides highly active even at very short peptide lengths. The long peptides interact very weakly with the lipids membrane. The antivirus mechanism of the biologically active peptides (peptaibols) sheds light on the potential use of peptaibols in plant viral disease control. The serious problems caused by drug resistant bacteria have created an urgent need for the development of alternative therapeutics. In this respect, AMPs are considered as promising antimicrobial agents for producing new generation antibiotics and also for improving plant resistance against bacterial and virus lesion. So it is reasonable to focus on small peptides.

Upflow anaerobic sludge blanket (UASB) reactors have been widely used for treatment of industrial wastewater. In this study, performance of a lab-scale up-flow anaerobic sludge blanket (UASB) reactor, treating a chemical synthesis-based pharmaceutical wastewater, was evaluated under different operating conditions. A (P.E) pipe with a diameter of 250 mm and total height of 120 cm and effective height of 100 cm with approximate volume of 49 liter was used as a reactor. The loading rates on reactor were increased in steps to assess the maximum loading capacity of the reactor to study the performance of reactor at different loading rates. The COD concentrations used in the present investigation ranges between 1850 mg/L to 15170 mg/L. The performance of the reactor up to 10.81 kg COD/m3.d was evaluated and the hydraulic retention times were examined. During this study, which lasted for 120 days, the temperature of the wastewater entering the reactor ranged from 30 to 35°C and no heat exchanger was used. Finally the removal ratio of COD with hydraulic retention time of 33.7 hours and organic loading rate of 10.81 kg COD/m3.day were 54 percent respectively.