Biofilm inhibition has been identified as a novel drug target for the development of broad-spectrum antibiotics to combat infections caused by drug-resistant bacteria. Although several plant-based compounds have been reported to have anti-biofilm properties, research on the anti-biofilm properties of bacterial bioactive compounds has been sparse. In this study, the efficacy of compounds from a cell-free supernatant of Bacillus subtilis against a biofilm formation of Pseudomonas sp. was studied through in vitro, in vivo and in silico studies. Here, in well diffusion method, Bacillus subtilis demonstrated antibacterial activity, and more than 50% biofilm inhibition activity against Pseudomonas sp. was exhibited through in vitro studies. Moreover, molecular docking and molecular dynamics (MD) simulation gave insights into the possible mode of action of the bacterial volatile compounds identified through GC-MS to inhibit the biofilm-formation protein (PDB ID: 7M1M) of Pseudomonas sp. The binding energy revealed from docking studies ranged from −2.3 to −7.0 kcal mol−1. Moreover, 1-(9H-Fluoren-2-yl)-2-(1-phenyl-1H-ttetrazole5-ylsulfanyl)-ethanone was found to be the best-docked compound through ADMET and pharmacokinetic properties. Furthermore, MD simulations further supported the in vitro studies and formed a stable complex with the tested protein. Thus, this study gives an insight into the development of new antibiotics to combat multi-drug-resistant bacteria.

Antibiotic resistance is an alarming threat all over the world, and the biofilm formation efficacy of bacteria is making the situation worse. The antagonistic efficacy of Klebsiella pneumoniae against one of the known fish pathogens, Aeromonas sp., is examined in this study. Moreover, Aeromonas sp.’s biofilm formation ability and in vivo pathogenicity on Artemia salina are also justified here. Firstly, six selected bacterial strains were used to obtain antimicrobial compounds against this pathogenic strain. Among those, Klebsiella pneumoniae, another pathogenic bacterium, surprisingly demonstrated remarkable antagonistic activity against Aeromonas sp. in both in vitro and in vivo assays. The biofilm distrusting potentiality of Klebsiella pneumoniae’s cell-free supernatants (CFSs) was likewise found to be around 56%. Furthermore, the volatile compounds of Klebsiella pneumoniae were identified by GC-MS in order to explore compounds with antibacterial efficacy against Aeromonas sp. through an in silico study, where 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) (PDB: 5B7P) was chosen as a target protein for its unique characteristics and pathogenicity. Several volatile compounds, such as oxime- methoxy-phenyl-, fluoren-9-ol, 3,6-dimethoxy-9-(2-phenylethynyl)-, and 2H-indol-2-one, 1,3-dihydro- showed a strong binding affinity, with free energy of −6.7, −7.1, and −6.4 Kcal/mol, respectively, in complexes with the protein MTAN. Moreover, the root-mean-square deviation, solvent-accessible surface area, radius of gyration, root-mean-square fluctuations, and hydrogen bonds were used to ensure the binding stability of the docked complexes in the atomistic simulation. Thus, Klebsiella pneumoniae and its potential compounds can be employed as an alternative to antibiotics for aquaculture, demonstrating their effectiveness in suppressing Aeromonas sp.

In this study, Pithraj (Aphanamixis polystachya) seed (PS) oil was used to produce biodiesel via trans-esterification process. The PS oil was extracted from seed using a soxhlet solvent extraction technique and the effect of temperature and heating rate on product distribution was investigated. The PS oil was pretreated (esterified) to combat the saponification reaction and other associated problems e.g., phase separation. The transesterification reactions were carried out and the optimum biodiesel yield was found 93.87%, when the reaction condition was as follows: addition of 50 wt.% methanol, 0.8 wt.% NaOH (both are on the basis of wt.% of PS oil addition), 60 °C reaction temperature and 90 min reaction time. Biodiesel produced from PS oil was characterized by various physico-chemical means and compared with international standards. The use of the produced biodiesel in blend with commercial diesel will bring a remarkable change in fuel economy of the country, will ensure a clean and safe environment and will demonstrate a way for ‘Waste to Energy’. Chemical Engineering Research Bulletin 21(2020) 43-48

Kalimatar seeds were evaluated for their physical characteristics and cooking qualities. Physical characteristics of Kalimatar seeds measured in millimeters per seed were as follows: length 6.65 +/- 0.11; breadth 4.76 +/- 0.09; and thickness 4.49 +/- 0.07. Cooking qualities of the seeds were evaluated as follows: 1,000-seed weight 199.95 +/- 0.34 g; 1,000-seed volume 152.0 +/- 0.58 mL; seed density 1.27 +/- 0.02 g/mL; hydration capacity 1386.1 +/- 2.63 g/kg; and swelling capacity 1493.4 +/- 3.82 mL/L. The cooking time of untreated Kalimatar seed was 187 +/- 3.15 min; soaking the seeds in different media for 12 h reduced the cooking time considerably. Sodium carbonate solution (2%) was found as the most suitable soaking medium, particularly followed by roasting the seeds. Soaking and/or roasting did not cause pronounced reduction in nutrient content of the sample. PRACTICAL APPLICATIONS Long cooking time severely restricts the utilization of Kalimatar, a protein-rich source. This study aims to evaluate the effect of soaking and/or roasting on the cooking time of Kalimatar seed to find out a feasible way out of the problem. We found that soaking and quick cooking system considerably reduces the cooking time of Kalimatar without pronounced nutrient loss. Both methods can be adopted very successfully on a household scale as well as at industrial level. However, quick cooking method is much better than soaking system. Again, quick cooking seeds are suitable for preservation. Moreover, this method improves the nutritional quality and palatability of the seeds