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Biosurfactants (BS) are microbial-derived molecules showing surface activity and emulsification properties. These compounds are good candidates to replace synthetic surfactants for industrial applications however, commercial and industrial use of BS is limited due to low yields and the high cost associated to their production. This work reports the production of a new BS synthesized by a marine Brevibacterium luteolum, in order to perform its purification and structural characterization. Significant medium components for BS production were studied using a 2 3 factorial design in shake flask cultures. Production medium using 4% of carbon source, 2% of nitrogen source and 20% of artificial sea water generated a BS with a surface tension of 27 mN m −1 . The BS was characterized as a mixture of lipopeptides containing fatty acid chains varying from 10 to 18 carbon units and 5% of total protein. Two proline-lipids with the fatty acid C 16:0 and C 18:0 respectively, and a lipopeptide with a fatty acid C 16:0 linked to a peptide sequence Phe-Ala-X-X-Pro-Pro-Thr (X = Leu/Ile) were identified as the surface-active compounds produced by B. luteolum . Mineral oil was utilized as main carbon source for the lipopeptide production suggesting that the marine bacterium and its BS product can be useful in bioremediation or enhance oil recovery (EOR). [ABSTRACT FROM AUTHOR]

Biosurfactants are surface active materials that are produced by some microorganisms. These molecules increase biodegradation of insoluble pollutants. In this study sediments and seawater samples were collected from the coastline of Bushehr provenance in the Persian Gulf and their biosurfactant producing bacteria were isolated. Biosurfactant producing bacteria were isolated by using an enrichment method in Bushnell-Hass medium with diesel oil as the sole carbon source. Five screening tests were used for selection of Biosurfactant producing bacteria: hemolysis in blood agar, oil spreading, drop collapse, emulsification activity and Bacterial Adhesion to Hydrocarbon test (BATH). These bacteria were identified using biochemical and molecular methods. Eighty different colonies were isolated from the collected samples. The most biosurfactant producing isolates related to petrochemical plants of Khark Island. Fourteen biosurfactant producing bacteria were selected between these isolates and 7 isolates were screened as these were predominant producers that belong to Shewanella alga , Shewanella upenei , Vibrio furnissii , Gallaecimonas pentaromativorans , Brevibacterium epidermidis , Psychrobacter namhaensis and Pseudomonas fluorescens . The largest clear zone diameters in oil spreading were observed for G. pentaromativorans strain O15. Also, this strain has the best emulsification activity and reduction of surface tension, suggesting it is the best of thee isolated strains. The results of this study confirmed that there is high diversity of biosurfactant producing bacteria in marine ecosystem of Iran and by application of these bacteria in petrochemical waste water environmental problems can be assisted. [ABSTRACT FROM AUTHOR]

The article focuses on a study regarding the purification and gene cloning of α-methyl carboxylic acid deracemizing enzyme 1 (MCAD1) from Brevibacterium ketoglutamicum KU1073. It states that (R)- and (S)-2-(4-chlorophenoxy) propanoic acid (CPPA) prepared through a racemic mixture was used in the study while microorganisms that deracemize CPPA were screened. Results show that MCAD1 should be classified into a medium chain acyl-coenzyme A (CoA) synthetases.

Abstract: Amplified ribosomal DNA restriction enzyme analysis (ARDRA), pulsed field gel electrophoresis (PFGE) and ribotyping were used to differentiate among 24 strains of Brevibacterium linens, Brevibacterium casei and Brevibacterium epidermidis obtained from type culture collections or isolated from various smear ripened cheeses. ARDRA was applied to the 16S rDNA. B. linens was shown to be a quite heterogenic group with 2 to at least 4 copies of rrn operons per strain with aberrant nucleotide sequences. AccI gave genus specific restriction patterns and was used to separate Brevibacterium from Corynebacterium species. The expected species specificity of TaqI applied to B. linens type culture strains, but not to all strains isolated from cheese. By AvaI restriction, B. casei and B. linens were differentiated from B. epidermidis and the orange pigmented Arthrobacter casei, a new species of coryneform bacteria; by XmnI restriction, B. linens and B. epidermidis were differentiated from B. casei. One of 4 B. linens genotypes could not be distinguished from B. casei by this method. Here, the typical orange B. linens pigments were used for classification, which was confirmed by partial sequencing of the 16S rDNA. [Copyright &y& Elsevier]

Nickel bioaccumulation capacity of a marine Brevibacterium sp., designated as X6, was evaluated to explore its potential application in the bioremediation of Ni2+ pollutants in marine environments. The minimum Ni2+ inhibitory concentration and maximum Ni2+ bioaccumulation of X6 were 1000 mg/L and 100.95 mg/g, respectively, higher than most reported strains. Among the co-existing metal ions in seawater, K+ caused a slight adverse impact on Ni2+ uptake, followed by Na+ and Ca2+, whereas Mg2+ drastically inhibited Ni2+ bioaccumulation. Other heavy metals such as Co2+, Zn2+ and Cd2+ moderately affected Ni2+ binding, but the adverse effect of Cu2+ was severe. The investigation of the mechanism of Ni2+ bioaccumulation revealed that 66.34% of the accumulated Ni2+ was bound to the cell surface. Carboxylic, hydroxyl, amino and thiol groups participated in Ni2+ binding, while carboxylic group contributed the most, while thiol group may be more involved in Ni2+ binding at low Ni2+ concentrations. [Display omitted] • A marine bacterium X6 can tolerate 800 mg/L Ni2+ and bind maximum 100.95 mg/g Ni2+. • K+, Na+ and Ca2+ slightly affect Ni2+ uptake, while the effect of Mg2+ is serious. • Cu2+, Zn2+ and Cd2+ are competitive to Ni2+ uptake, but Cu2+ is the strongest. • Most Ni2+ is bound on the cell surface, while the other is transported into the cell. • Functional groups contribute to Ni uptake and carboxyl group is the most important. [ABSTRACT FROM AUTHOR]

The Tea rhizosphere microbial community harbor diverse plant growth promoting (PGP) rhizobacteria and are relatively less explored. In our study, we isolated 23 distinct bacterial morphotypes from the tea garden of Assam, India. The isolates were screened for their plant growth promotion (PGP) and antifungal traits against three pathogenic fungi, namely Rhizoctonia solani , Corticium rolfsii , and Fomes lamaensis. Out of 23 isolates, 7 isolates showed potential in antifungal activities, amongst which, isolate A6 was found to have promising PGP and antifungal traits. Isolate A6 also exhibited biosurfactant production abilities in the presence of 2% dextrose as a carbon source. Biochemical and molecular characterization revealed its identity as Brevibacterium sediminis. Further quantification assay showed the amount of indole acetic acid (IAA) production (72.51 ± 2.18 μg/mL) and phosphate solubilization (60.644 ± 3.098 μg/mL) by the isolate A6. The PGP activity of the isolate was validated by in vitro trials on rice seedlings. A6 treated seedlings showed a significantly higher root length (p = 0.0350), shoot length (p < 0.0001), and fresh weight (p = 0.0001), however, no significant difference was observed in dry weight. Our findings also demonstrated its ability for biofilm formation. Collectively, this study suggests that the isolate A6 could be a potential PGPR candidate and demands further investigation for developing a consortium with other PGPR for future on-site (in field) applications. • Rhizobacteria Brevibacterium sediminis A6 isolated from Tea rhizosphere of Assam has potential of plant growth promotion. • Along with PGPR and antifungal traits, it also produces biosurfactant by utilizing dextrose as carbon source. • B. sediminis A6 positively influenced growth parameters of rice seedlings tested in vitro however dry weight showed no significant difference. [ABSTRACT FROM AUTHOR]