Cumhuriyet Science Journal e-ISSN: 2587-246X Cumhuriyet Sci. J., 41(4) (2020) 784-801 ISSN: 2587-2680 http://dx.doi.org/10.17776/csj.774034 *Corresponding author. Email address: rev20032002@yahoo.com http://dergipark.gov.tr/csj ©2020 Faculty of Science, Sivas Cumhuriyet University The utilisation of herbicides by indigenous microorganisms obtained from Ago-Iwoye, Nigeria, for enhanced growth rates and as carbon source in-vitro Adewole SEBIOMO 1, * , Folake M. BANJO 1 1 Tai Solarin University of Education, Department of Biological Sciences, Ijagun/ NIGERIA Abstract This study determined the abilities of indigenous microorganisms to utilise atrazine, xtravest, gramoxone and glyphosate as a carbon source and for their growth. Isolation of microorganisms was done using the spread plate method on the solid mineral salts medium with each herbicide added to separate plates. The plates were incubated at 30°C for 5 days for bacteria and at 30 o C for 7days for fungi. B. subtilis, P. aeruginosa, P. florescences, P. putida, Aspergillus niger, A. tamarii, Fusarium oxysporum, and P. chrysogenum were isolated in all the herbicide treated soils. Bacillus subtilis recorded the highest optical density value of 1.401 (logCFU/ml) on the 25 th day and viable count value of 9.08 (log CFU/ml) (1.21×10 9 cfu/ml) on the 20 th day during growth on glyphosate. F. oxysporum recorded the lowest pH of 4 in gramoxone on the 25 th day of incubation and the highest count of 6.10×10 4 cfu/g on the 20 th day during atrazine utilisation. B. subtilis, A. niger and F. oxysporum showed the best abilities to utilise the herbicides for growth and as carbon source. Indigenous microorganisms used in this study successfully utilised the herbicides as carbon source and for growth hence they could be used in bioremediation. Article info History: Received: 26.07.2020 Accepted: 11.11.2020 Keywords: Herbicides, Viable Counts, Biodegradation, Bioremediation 1. Introduction Herbicides are used to control weeds in modern agriculture. When herbcides are applied to the field, they control target weeds, as well as have potential residual impact in soil [1]. Varying toxicity of herbicides in soil may cause changes in microbial community structure and function, and concomitantly influencing soil health and ecosystem processes [1]. Microbes are also exposed to these herbicides over a period of time before breakdown by microbes and environmental factors [2]. There are several mechanisms for the clean-up of herbicides in soils, such as chemical treatment, volatilization and incineration [3]. Chemical treatment and volatilization are very effective in herbicide clean up. However, in the long run large volumes of acids and alkalis, which are lethal to the living organisms in the environment are produced and subsequently must be removed. Incineration, which is a very reliable physical-chemical method for destruction of these compounds, has met serious public opposition, because of its potentially toxic emissions, and its elevated economic costs [4]. These physical-chemical cleaning technologies are costly and inefficient because the contaminated soil has to be moved to a storage area where it can be processed [5]. As a result of environmental concerns associated with the accumulation of pesticides in food products and water supplies, it is very important to develop safe, convenient and cheap methods for pesticide removal [4]. Cosequently biological techniques involving biodegradation of organic compounds by microorganisms have been developed [6]. The use of microorganisms, either naturally occurring or introduced, to degrade pollutants is called bioremediation [7]. Fungi are generally more tolerant to high concentrations of polluting chemicals than bacteria [8]. Therefore, some fungi represent a powerful and important tool in soil bioremediation. Some species of fungi have already been used in bioremediation [9]. Glyphosate [N- (phosphonomethyl) glycine, glyphosate], a post- emergence nonselec¬tive broad-spectrum herbicide, and glyphosate-containing herbicides are the most extensively used herbicides in agriculture for the control of many annual and perennial weeds [10-11]. In some cases, glyphosate usage may threaten