This is the first report of an isolate of V. harveyi which utilizes glycerol as the sole carbon source for PHB production with high biomass yield. This isolate could be of use as candidate species for commercial PHB production using glycerol as the feed stock or as source of genes for recombinant PHB production or for synthetic biology.

Cholera, caused by the Gram-negative bacterium Vibrio cholerae, has ravaged humanity from time immemorial. Although the disease can be treated using antibiotics along with administration of oral rehydration salts and controlled by good sanitation, cholera is known to have produced mayhems in ancient times when little was known about the pathogen. By the 21st century, ample information about the pathogen, its epidemiology, genetics, treatment and control strategies was revealed. However, there is still fear of cholera outbreaks in developing countries, especially in the wake of natural calamities. Studies have proved that the bacterium is mutating and evolving, out-competing all our efforts to treat the disease with previously used antibiotics and control with existing vaccines. In this review, the major scientific insights of cholera research are discussed. Considering the important role of biofilm formation in the V. cholerae life cycle, the vast availability of next-generation sequencing data of the pathogen and multi-omic approach, the review thrusts on the identification of suitable biofilm-inhibiting targets and the discovery of anti-biofilm drugs from nature to control the disease.

Vibrio cholerae, a causative agent of the waterborne disease cholera, still threatens a large proportion of world's population. The role of biofilm formation in V. cholerae pathogenesis is well established, as it provides the bacterium enhanced tolerance to antimicrobial agents and increased transmission. In the present study, four medicinal plants used in traditional medicines with antidiarrheal properties were evaluated for its antibiofilm activity. Methanol extracts of these plants (Centella asiatica, Elephantopus scaber, Camellia sinensis, and Holarrhena antidysenterica) showed promising antibiofilm activity against V. cholerae with crystal violet and air-liquid interface coverslip assays. Results revealed that C. asiatica, E. scaber, C. sinensis, and H. antidysenterica extracts significantly inhibited biofilm formation by approximately 75, 76, 78, and 55% at concentrations of 3, 2, 1, and 0.6 mg/mL, respectively. A promising antibiofilm activity of ∼89% inhibition at 1.5 mg/mL concentration was observed when a combination of E. scaber and C. sinensis was used. The herbal extracts were thermostable at a temperature range of 40 to 100°C. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that the viability of bacteria was not affected by treatment with these plant extracts. Gene expression studies revealed that extracts of H. antidysenterica leaf, H. antidysenterica bark, and the whole plant of E. scaber and C. asiatica down-regulate aphA or aphB, the major regulator genes modulating both virulence and biofilm formation. Hence, we propose that these herbal combinations could serve as a multifaceted approach to combat the pathogen and also, in turn, reduce antimicrobial resistance development.

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