  Citation: Mozumder, A.B.; Chanda, K.; Chorei, R.; Prasad, H.K. An Evaluation of Aluminum Tolerant Pseudomonas aeruginosa A7 for In Vivo Suppression of Fusarium Wilt of Chickpea Caused by Fusarium oxysporum f. sp. ciceris and Growth Promotion of Chickpea. Microorganisms 2022, 10, 568. https://doi.org/10.3390/ microorganisms10030568 Academic Editor: Tim J. Dumonceaux Received: 31 December 2021 Accepted: 7 February 2022 Published: 5 March 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). microorganisms Article An Evaluation of Aluminum Tolerant Pseudomonas aeruginosa A7 for In Vivo Suppression of Fusarium Wilt of Chickpea Caused by Fusarium oxysporum f. sp. ciceris and Growth Promotion of Chickpea Atifa Begum Mozumder , Kakoli Chanda, Ringhoilal Chorei and Himanshu Kishore Prasad * Department of Life Science and Bioinformatics, Assam University, Silchar 788011, India; atifamozumder@gmail.com (A.B.M.); kakolimic@gmail.com (K.C.); choreiringhoilal@gmail.com (R.C.) * Correspondence: himanshu.k.prasad@aus.ac.in or himanshukprasad@gmail.com Abstract: Chickpea wilt, caused by Fusarium oxysporum f. sp. ciceris, is a disease that decreases chickpea productivity and quality and can reduce its yield by as much as 15%. A newly isolated, moss rhizoid-associated Pseudomonas aeruginosa strain A7, demonstrated strong inhibition of Fusarium oxysporum f. sp. ciceris growth. An in vitro antimicrobial assay revealed A7 to suppress the growth of several fungal and bacterial plant pathogens by secreting secondary metabolites and by producing volatile compounds. In an in vivo pot experiment with Fusarium wilt infection in chickpea, the antagonist A7 exhibited a disease reduction by 77 ± 1.5%, and significantly reduced the disease incidence and severity indexes. Furthermore, A7 promoted chickpea growth in terms of root and shoot length and dry biomass during pot assay. The strain exhibited several traits associated with plant growth promotion, extracellular enzymatic production, and stress tolerance. Under aluminum stress conditions, in vitro growth of chickpea plants by A7 resulted in a significant increase in root length and plant biomass production. Additionally, hallmark genes for antibiotics production were identified in A7. The methanol extract of strain A7 demonstrated antimicrobial activity, leading to the identification of various antimicrobial compounds based on retention time and molecular weight. These findings strongly suggest that the strain’s significant biocontrol potential and plant growth enhancement could be a potential environmentally friendly process in agricultural crop production. Keywords: Fusarium oxysporum f. sp. ciceris; aluminum; biocontrol; chickpea; PGPR; Pseudomonas aeruginosa A7 1. Introduction Chickpeas (Cicer arietinum L.) are considered to be one of the oldest legumes known from ancient times. Most likely, it originated in southeastern Turkey and Syria’s adjacent areas [1]. Globally, it is a valuable crop and about 2.3 million tons enter the world market annually [2]. The major chickpea legume grain-producing regions are in southern and South-Eastern Asia, Africa, and Australia [2]. It is estimated that India produces 9.075 million tons of chickpeas annually, accounting for 65% of the total production of chickpeas. The remarkable growth of chickpea pulse has been documented in India, comprising the most significant production (47%; 10.90 MT) among all pulse crops in 2019–2020 [2]. Chickpeas are sustainable legumes with nutritional value for human and animal consumption as well as soil fertility. Chickpeas seeds and leaves are an excellent source of carbohydrates, vitamins, fibers, and proteins. Chickpeas play a leading role in food safety in the world by supplying the protein deficit of daily food rations [3]. Chickpeas-based diets are recommended to combat lifestyle disease since they contain several essential minerals such as calcium, phosphorus, iron, and zinc among other substances, including phenolics and oligosaccharides [3]. There are numerous living and Microorganisms 2022, 10, 568. https://doi.org/10.3390/microorganisms10030568 https://www.mdpi.com/journal/microorganisms