Aims:  To compare effective cell disruption methods for lipid extraction from fresh water microalgae. Methods and Results:  Chlorella sp., Nostoc sp. and Tolypothrix sp. were isolated from fresh water ponds in and around Gandhigram, Dindigul District, Tamilnadu, India, and used for lipid extraction. Different methods, including autoclaving, bead beating, microwave, sonication and a 10% NaCl solution treatments, were tested to identify the most effective cell disruption method. The total lipids from three microalgal species were extracted using a mixture of chloroform and methanol. Fatty acid composition was detected by gas chromatography (GC). Nostoc sp. and Tolypothrix sp. showed higher oleic acid content of 13·27 mg g−1 dw and 17·75 mg g−1 dw, respectively, whereas Chlorella sp. had high linoleic acid content of 17·61 mg g−1 dw when the cells were disrupted using the sonication method. Conclusions:  Finally, the sonication method was found to be the most applicable and efficient method of lipid extraction from microalgae. The highest lipid content was extracted from Chlorella sp. Significance and Impact of the Study:  In biodiesel production from microalgae, lipid extraction is a crucial step and important as cell disruption comes in this step. Therefore, the appropriate cell disruption method and device is a key to increase the lipid extraction efficiency.

Probiotic bacteria are beneficial to the health of poultry animals, thus are used as alternative candidates for antibiotics used as growth promoters (AGPs). However, they also reduce the body weight gain due to innate bile salt hydrolase (BSH) activity. Hence, the addition of a suitable BSH inhibitor along with the probiotic feed can decrease the BSH activity. In this study, a BSH gene (981 bp) encoding 326-amino acids was identified from the genome of Lactobacillus gasseri FR4 (LgBSH). The LgBSH-encoding gene was cloned and purified using an Escherichia coli BL21 (DE3) expression system, and its molecular weight (37 kDa) was confirmed by SDS–PAGE and a Western blot analysis. LgBSH exhibited greater hydrolysis toward glyco-conjugated bile salts compared to tauro-conjugated bile salts. LgBSH displayed optimal activity at 52°C at a pH of 5.5, and activity was further increased by several reducing agents (DTT), surfactants (Triton X-100 and Tween 80), and organic solvents (isopropanol, butanol, and acetone). Riboflavin and penicillin V, respectively, inhibited LgBSH activity by 98.31 and 97.84%. A homology model of LgBSH was predicted using EfBSH (4WL3) as a template. Molecular docking analysis revealed that the glycocholic acid had lowest binding energy of -8.46 kcal/mol; on the other hand, inhibitors, i.e., riboflavin and penicillin V, had relatively higher binding energies of -6.25 and -7.38 kcal/mol, respectively. Our results suggest that L. gasseri FR4 along with riboflavin might be a potential alternative to AGPs for poultry animals.

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