Please cite this article in press as: S.N. Muslim, et al., Int. J. Biol. Macromol. (2017), http://dx.doi.org/10.1016/j.ijbiomac.2017.08.146 ARTICLE IN PRESS G Model BIOMAC-8139; No. of Pages 7 International Journal of Biological Macromolecules xxx (2017) xxx–xxx Contents lists available at ScienceDirect International Journal of Biological Macromolecules j ourna l h o mepa ge: www.elsevier.com/locate/ijbiomac Chitosan extracted from Aspergillus ﬂavus shows synergistic effect, eases quorum sensing mediated virulence factors and bioﬁlm against nosocomial pathogen Pseudomonas aeruginosa Sahira Nsayef Muslim a , Israa M.S. AL Kadmy a,∗ , Alaa Naseer Mohammed Ali a , Batool Kadham Salman c , Mohammad Ahmad d , Saba Saadoon Khazaal a , Nadheema Hammood Hussein a , Sraa Nsayef Muslim b a Department of Biology, College of Science, AL-Mustansiryiah University, Baghdad, Iraq b Department of Geophysics, College of Remote sensing and geophysics, AL-Karkh University, Baghdad, Iraq c Ministry of Health, Baghdad, Iraq d Medical Surgical Nursing Department, College of Nursing, King Saud University, Saudi Arabia a r t i c l e i n f o Article history: Received 28 July 2017 Received in revised form 14 August 2017 Accepted 27 August 2017 Available online xxx Keywords: Antibacterial activity Chitosan Aspergillus ﬂavus a b s t r a c t The biological methods for extraction of chitosan were used as alternative procedures for chemical meth- ods In biological methods, the chitosan was extracted from A. ﬂavus by using of Lactobacillus paracasei for demineralization and Bacillus subtilis for deproteinization. The yield of extracted chitosan reached to 53.8%, pH was 7.8 and complete solubility in 1% acitic acid. Puriﬁed chitosan had the ability to reduce the bioﬁlm forming capacity of P. aeruginosa clearly visible in light microscopic staining and scanning electron microscopy. The QS dependent phenotype and QS regulated gene expression was signiﬁcantly reduced in the inﬂuence of chitosan. A signiﬁcant decrease in bioﬁlm formation was seen in the presence of chitosan. The chitosan treatment showed a decrease in the expression of lasR and rhlR genes. Same time production of pyocyanin and proteases was also inhibited in dose dependent manner. Chitosan led to increasing antimicrobial activity of antibiotics and had synergism effect, thus chitosan may be a useful adjuvant agent for the treatment of many bacterial infections in combination with antibiotics. © 2017 Elsevier B.V. All rights reserved. 1. Introduction The genus Aspergillus is classiﬁed under the ascomycota phylum. A. ﬂavus is predominantly a saprophyte surviving on plant and ani- mal debris, increase sporulation in hot and dry weather [1]. The ability of A. ﬂavus to survive in harsh conditions allows it to eas- ily out-compete other organisms for substrates in the soil or in the plant [2]. Chitosan is chemically deﬁned as a copolymer of -(1, 4) glucosamine (C6H11O4N)n [3]. Chitosan is essentially composed of –1, 4 D-glucosamine (GlcNAc) linked to N-acetyl-d-glucosamine residues, derived from de-Nacetylation of chitin. Chitosan is less commonly found in living organisms than chitin and can be found in the cell walls of certain groups of fungi, partic- ularly Zygomycetes fungi including Absidia, Gongronella, Mucor and ∗ Corresponding author at: Al-Mustansiriyah University, College of Science, Department of biology, Branch of Biotechnology, Baghdad, Iraq. E-mail addresses: israaalkadmy@gmail.com, stsf@uomustansiriyah.edu.iq (I.M.S.A. Kadmy). Rhizopus [4]. Chitosan shows many unique properties, such as bio- compatibility, biodegradation, biological activity and low-toxicity [5]. Chitosan has recently many ﬁelds of applications such as in cos- metics, pharmaceuticals, food additives and agriculture. It is used as a component of toothpaste, hand and body creams, shampoos, body creams, lowering of serum cholesterol, cell, and enzyme immobi- lizer, as a drug carrier, material for the production of contact lenses, or eye bandages, etc. Chitosan has the important food related appli- cations which include puriﬁcation of drinking water, recovering protein from ﬁsh wash water and meat processing plants, using in animal feeds, clarifying wine etc. Chitosan is used in the thin layer chromatography for the separation of nucleic acid [3]. Chitosan is earlier known to have an antibacterial and antibioﬁlm effect [3–5]. The purpose of this study was to extract chitosan from Aspergillus ﬂavus by using biological methods and evaluates its anti-quorum (QS) sensing properties against Pseudomonas aeruginosa QS depen- dent phenotype of P. aeruginosa and expression of QS regulated lasR and rhlR genes were assayed upon treatment with puriﬁed chi- tosan. A congo red staining and scanning electron microscopy was http://dx.doi.org/10.1016/j.ijbiomac.2017.08.146 0141-8130/© 2017 Elsevier B.V. All rights reserved.