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Bioemulsifiers (BE) and biosurfactants (BS) are considered as multifunctional biomolecules of 21st century because of their functional abilities and eco‐friendly properties. They are produced by various microorganisms under versatile and extreme environmental conditions. They have tremendous applications in various industries such as petroleum, food, medicine, pharmaceutical, chemical, paper & pulp, textile, and cosmetics. Currently, they are also considered as “green molecules” because of their wide applications in bioremediation of soil. Their importance has been increasing day by day in the global market as they are the natural resources with high‐aggregate value. Although, there are numerous reports on BE and BS production by different bacteria, Acinetobacter spp. acquired special attention among all. This is because it is the earliest member known for the production of bioemulsifier. Emulsan and Alasan are the best examples of the commercially used BE produced by Acinetobacter spp. These BE are mainly used in microbial enhanced oil recovery and biodegradation of toxic compounds. This review is focused on BE and BS produced by Acinetobacter spp., their characterization and applications in different fields. This is the first review on genus Acinetobacter which defines independently about different types of BE and BS produced by it. It will also address the need of exploration of these molecules from various sources and their applications for the benefit of mankind and sustainable environment.

An Acinetobacter species identified as A. haemolyticus A19 produces an antibiotic and the enzyme chitinase. The antibiotic produced by A. haemolyticus A19 was extracellular and inducible by co-cultivation with Klebsiella pneumoniae in the optimum ratio 2:1, respectively. pH 7, temperature 28 °C, and addition of 2% (w/v) NaCl are the most suitable environmental conditions for production and activity of the antibiotic. The antibiotic was produced in the early stationary growth phase (48 h) of A. haemolyticus A19. It has a very broad spectrum of antimicrobial activity against plant and human pathogenic bacteria and fungi. The antibiotic was extracted with ethyl acetate and purified by column chromatography with further purification by preparative thin-layer chromatography. Yield of the antibiotic was 15 mg/l. The antibiotic was active at very low concentrations, for example 50 μg/ml, and was water-soluble. It was stable at room temperature for up to 7 days. (1)H NMR analysis revealed the antibiotic was a pyrrolnitrin. It was found that pyrrolnitrin production by A. haemolyticus A19 was encoded by plasmid pUPI126 of molecular weight 25.7 kb. Plasmid pUPI126 was transferred to E. coli HB101 at a frequency of 5 × 10(-5) per μg DNA. It was also conjugally transformed to E. coli HB101 rif (r) mutants at a frequency of 5.9 × 10(-8) per recipient cell. Plasmid pUPI126 was 100% stable in Acinetobacter and 95% stable in E. coli HB101. Transconjugants and transformants both produced the antibiotic. This is the first report of plasmid-mediated pyrrolnitrin production by A. haemolyticus A19 isolated from wheat rhizosphere.

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