Carotenoids are natural potent antioxidants and free radical scavengers which are able to modulate the pathogenesis of some cancers and heart diseases in human, indicating their importance in being provided through the diet. Mucor circinelloides accumulates β-carotene as the main carotenoid compound and has been used as a model organism in carotenogenic studies. In the present study, the potential of two M. circinelloides strains to accumulate β-carotene was investigated under light and dark conditions. The results, which were quantitated by HPLC, showed that CBS 277.49 accumulated higher pigment in comparison to WJ11 under both conditions. Continuous illumination triggered the pigment accumulation up to 2.7-fold in strain CBS 277.49 and 2.2-fold in strain WJ11 in comparison to dark. The mRNA analysis of the four key genes involved in isoprenoid pathway by RT-qPCR showed higher transcriptional levels in CBS 277.49 as compared to WJ11, indicating that the pigment production metabolic machinery is more active in CBS 277.49 strain. A new scope for further research was established by this work for improved β-carotene production in the high producing strain CBS 277.49.

In the present study, the impact of eight phytohormones from six different classes on the growth, lipid and docosahexaenoic acid (DHA) biosynthetic capacity of Aurantiochytrium sp. SW1 (SW1) was evaluated. Kinetin (KIN), jasmonic acid (JA) and gibberellic acid (GA) significantly enhanced the growth and DHA production of SW1 by 16%–28% and 66%–84% in comparison to the control, respectively. The synergistic effect of these three phytohormones, evaluated by the response surface methodology (RSM), showed that a combination of 3.6 mg/L GA, 2.0 mg/L KIN and 20.0 mg/L JA further increased the growth and DHA production of SW1 by 16% to 28% and 22% to 36%, respectively, in comparison to the individual supplementation. The synergistic effect of these phytohormones was also shown to be time-dependent, where feeding at 24 h of cultivation led to 15%, 26% and 35% further increments in the biomass, lipid and DHA production in comparison to that of 0 h, respectively. The determination of stress markers, antioxidant enzymes and key enzymes involved in fatty acid biosynthesis aided to elucidate the potential mechanism underlying the improvement of growth and DHA production by SW1 at various times of feeding. Supplementation with the phytohormones at 24 h exhibited the maximum impact on reducing the level of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as augmented the antioxidants (superoxide dismutase and catalase) and key metabolic enzymes involved in lipogenesis (malic, glucose-6-phosphate dehydrogenase and ATP-citrate lyase) in comparison to the control and other time points. This study signifies the potential application of phytohormones for improving the growth, lipid and DHA production in Aurantiochytrium spp.

The effects of various carbon sources and cultivation conditions on the growth kinetics, lipid accumulation, and medium-chain fatty acid (MCFA) production of Mucor circinelloides (MC) was investigated for 72 h in shake flask cultivation. Our previous investigation reported increments of 28 to 46% MCFAs among total cell lipids when the MC genome was genetically modified, in comparison to the wild-type. However, the growth of the engineered strain M65-TE-04 was adversely affected. Therefore, the current study was designed to enhance the growth, lipid production, and MCFA productivity of engineered M. circinelloides by optimizing the pH, agitation speed, temperature, and carbon sources. The findings for individual variables disclosed that the highest biomass (17.0 g/L) was obtained when coconut oil mixed with glucose was used as a carbon source under normal culture conditions. Additionally, the maximum lipid contents (67.5% cell dry weight (CDW)), MCFA contents (53% total fatty acid (TFA)), and overall lipid productivity (3.53 g/L·d) were attained at 26 °C, pH 6.0, and 150 rpm, respectively. The maximum biomass (19.4 g/L), TFA (14.3g/L), and MCFA (4.71 g/L) contents were achieved with integration of a temperature of 26 °C, pH 6.0, agitation speed 300 rpm, and coconut oil mixed medium as the carbon source. This work illustrates that biomass, TFA, and MCFA contents were increased 1.70–2.0-fold by optimizing the initial pH, agitation speed, temperature, and carbon sources in the M. circinelloides engineered strain (M65-TE-04) in comparison to initial cultivation conditions.

Diethylamine nitrosamine (DEN), as an initiator of liver tumor, and carbon tetrachloride (CCl4), as a tumor promoter, have been used to study the molecular events of liver cancer in animal models. Recently, our in vitro study reported BLE (Berberis lycium Royle ethanol extract) as the most effective agent against liver cancer, thus we continued our study in vivo to assess the hepatoprotective effect of BLE and its most active alkaloid, berberine, in albino mice (70 male). Moreover, we investigated the biochemical/immunohistochemical effects of a single alkaloid versus the effect of Berberis extract in mice liver. Hepatic cancer was induced in mice by a single intraperitoneal injection with DEN (100 mg/kg b.wt), followed by biweekly injections of CCl₄ (0.5 mL/kg) for 30 days. The development of liver cancer was assessed after 60 days of DEN injection by measuring the elevated level of the serum tumor marker alpha-fetoprotein (AFP) and liver function test (ALT, AST, ALP, and BUN) markers. After the confirmation of liver cancer development, the BLE extract and berberine were fed to mice for 90 days and the serum biomarkers for liver injury (LFTs and AFP) were measured again. Overall, berberine (120 mg/kg b.wt) proved to be a stronger agent in reducing the symptoms of HCC in mice, as compared with BLE. Histopathological analysis agreed well with the biochemical observations. Immunohistochemistry analysis suggested significant suppression of the quantitative expression of the key oncogene cyclin D1 at low (60 mg/kg) and high (120 mg/kg) doses of berberine. These findings implicate the amelioration of hepatocarcinoma by berberine more prominently in mice, by suppression of cyclin-dependent kinase activator (CD1) expression, reducing LFTs, as well as AFP, in the serum. Thus, our findings are novel, as berberine may help in controlling the perturbation in CD1 associated with aggressive forms of HCC. However, future studies should be directed at finding out whether berberine has any effect on inhibitors (p27 and CDKI) of cyclin-dependent kinase too.