International Journal of Research in Environmental Science (IJRES) Volume 3, Issue 1, 2017, PP 10-19 ISSN 2454-9444 (Online) http://dx.doi.org/10.20431/2454-9444.0301002 www.arcjournals.org ©ARC Page | 10 Application of Selected Malaysian Wild Plant Leaves as Potential Control of Cyanobacterial Bloom Tengku Nadiah Yusof a , Mohd. Rafatullah a,* , Norli Ismail a , Zarina Zainuddin b , Japareng Lalung a,* a School of Industrial Technology, Universiti Sains Malaysia, 11800, Pulau Penang, Malaysia b Department of Biotechnology, International Islamic University Malaysia, Jalan Sultan Ahmad Shah, 25200 Kuantan, Pahang, Malaysia Abstract: Efficient cyanobacterial bloom management is important because a bloom in a water body may cause problems such as unpleasant odour and taste, and most importantly, toxin production that are potentially fatal to human and animals. Previous researches have shown that various aquatic and terrestrial plants, especially traditional herbs and shrubs, were able to inhibit the growth of cyanobacteria; the most common plant used to control cyanobacterial growth is barley straw. Therefore, if any wild terrestrial leaf can perform the same control, it would provide a low cost and environmental friendly alternative of cyanobacterial management. In this study, 10 g/L of ten different species of terrestrial wild plant leaves leachates from Penang, Malaysia were individually tested for their abilities to inhibit the growth of eight isolated cyanobacteria namely Microcystis sp., Pseudoanabaena sp., Planktothrix sp., Limnothrix sp., Ocsillatoria sp., Synecocystis sp. and two Synechococcus spp. for 15 days. The results showed that most leaves effectively controlled all cyanobacterial growth but at different rates, depending on the species of cyanobacteria and the species of plant leaves used. The outcomes suggest that the wild plant terrestrial leaves released effective anti-cyanobacterial substances, giving new insight to terrestrial leaves as natural biological controls of cyanobacterial bloom. Keywords: Algae, Biological control, Cyanobacteria, Plant, water body 1. INTRODUCTION Cyanobacteria or also known as blue-green algae are prokaryotes with unique characteristics. Unlike other prokaryotes, cyanobacteria contain chlorophyll that enables them to obtain their nutrients mainly through photosynthetic action, making them important to provide oxygen in the water environment. However, excessive growth of cyanobacteria leads to the formation of visible cyanobacteria, or cyanobacterial blooms, and can cause several problems such as unpleasant odour and taste, and most importantly, toxin production[1]. Consumption or direct contact of cyanobacterial toxins can lead to severe health consequences. For instance, hepatotoxic microcystin was the cause of death of 60 dialysis patients in Brazil[2] and cylindrospermopsin has led to the hospitalisation of 148 children in Palm Island, Australia[3]. Currently, toxic cyanobacteria can be detected in more than 65 countries, including Thailand[4], Singapore[5], and Malaysia, which has confirmed the presence of toxic cyanobacteria in 2015 [6]. Increasing concern on harmful and unpleasant cyanobacteria blooming in the freshwater environment leads to extensive researches on cyanobacterial growth control. Currently, the most widely used chemical for water treatment, copper (II) sulphate (CuSO 4 ) has harmed a wide spectrum of species, risking a secondary pollution in the water environment[7]. While physical treatments such as sedimentation has lowered the secondary pollution risk, the treatments can injure other organisms and are usually energy consuming and expensive[7]. Hence, more scientists are in search of biological- derived treatments as an alternative. In general, ideal anti-cyanobacterial compounds are characterized by a strong inhibition to cyanobacteria and is non-toxic to other organisms, readily degraded in the environment, inexpensive and safe to the environment[7].The effectiveness of the compounds which is influenced by hydrophilicity and hydrophobicity is also one of the important characteristics [8]. In addition, ideally, an anti-cyanobacterial compound should be able to inhibit most cyanobacterial species. If the inhibition is species specific, the compound may enhance the growth of other cyanobacterial species, which is undesirable if the enhanced cyanobacterial species are a toxin-producing species[9].