The lipopeptide biosurfactants' chemical characteristics from the lactic acid bacteria isolated from milk and milk products were studied and their effect on maize plant growth. The oil displacement test was performed as a primary screening method to select the BS producing bacteria. Enterococcus faecium LM5.2 had the maximum emulsi cation index of 45.1±3 and reduced the surface tension to 32.98 ± 0.23% among all the isolates. E. faecium LM5.2 e ciently produced 945.26 ± 4.62 mg/l biosurfactants within 48 hours in MRS broth under the optimum conditions. The con rmation of the identity of the isolate LM5.2 was done with physiochemical tests and 16S rRNA gene sequencing. The molecular phylogenetic relationship was evaluated by the Neighbour-Joining phylogenetic method. The biosurfactant was puri ed by TLC and identi ed as lipopeptide-like iturines and surfactins based on R f values. Mass spectroscopy, NMR, and FTIR analysis also con rmed the biosurfactant's identity as the derivatives of iturin and surfactin. Both the biosurfactant and its producer bacterium were evaluated for their plant growth-promoting activity, and it was found that the biosurfactant and the bacterium could enhance plant growth. To the best of our knowledge, this is the rst report of lipopeptide biosurfactant production from Enterococcus faecium. Moreover, the study also showed that the biosurfactant and biosurfactant producing E. faecium LM5.2 could be an eco-friendly plant growth-promoting agent.
Postprandial hyperglycemia (PPG) is among the earliest signs related to type 2 diabetes. Targeting the α-amylase enzyme responsible for the initial stage of carbohydrate digestion can be an effective strategy to control the PPG. With this objective, about 300 Lactic acid bacteria were obtained from different ethnic fermented foods of Sikkim and screened for α-amylase inhibitor (AAI) activity. Five isolates of Lactobacillus (Lb.) plantarum were found to inhibit α-amylase whose inhibitory potential was similar to that of copper sulfate and acarbose. Maximum AAI activity was observed within 24 hours of incubation. All the isolates were also assessed for other probiotic properties including bacterial adherence to hydrocarbons, utilization of prebiotic components, etc. Among the safety features of the isolates tested, none of the isolates was hemolytic and neither could hydrolyze gelatin. Most of the isolates were sensitive to ampicillin, chloramphenicol, and erythromycin out of twelve antibiotics tested. These isolates also showed good response to in vitro simulation of oro-gastric-intestinal transit which confirms its ability to survive in the gastrointestinal tract. Therefore, these Lb. plantarum isolates can be potential probiotic candidates with aamylase inhibitory activity which can be further exploited for the management of postprandial hyperglycemia.
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