Valorisation of prawn carapace waste by Exiguobacterium sp GM010 for pilot scale pigment production and its safety efficacy in Wistar rats

Abstract

Purpose Utilisation of prawn carapace hydrolysate by Exiguobacterium sp GM010 for the growth and bioactive pigment production as fermentative substrate. To produce the pigment in pilot scale, the culture conditions were optimized and safety efficacy studies of the pigment were evaluated for commercial application in food and nutraceutical industries. Methods Exiguobacterium sp GM010 was grown in prawn carapace (biowaste) hydrolysate as fermentative substrate in a 10L medium using a 15L capacity fermentor. Based on our previous studies, fermentation parameters were set (pH 8.0, 30˚C, five days) by varying the aeration (0.5 to 3.0L min− 1). The pigment produced was quantitatively and qualitatively analysed in comparison with pigment produced in lab scale fermentation. Both acute (OECD 423) and sub-acute (OECD 427) toxicity studies were performed to determine its safety efficacy. Results The biomass and pigment extract yield were 28.76 ± 1.78 and 0.82 ± 0.04 g/L, respectively, at 1.5 L of aeration and higher than other aeration concentrations. The UV-visible spectrum of pigment extract revealed the absorption peak at 357, 466, and 491nm. The colour distribution of pigment was in the yellowish-orange region of the CIE Lab spectrum. Similar qualitative and quantitative pigment characteristics were observed in the fermentor and flask. The acute and sub-acute toxicity of the pigment extract confirmed no significant changes in feed intake, body weight (bw) gain and relative vital organ weight in Wistar rats. Similarly, no significant changes in biochemical and haematological parameters at 250, 500 and 1000 mg kg− 1 bw confirmed no sign of toxicity. Histopathological examination of all the vital organs was regular. Serum biochemistry results of the treated and control groups have shown insignificant changes. Conclusion Prawn carapace hydrolysate can be valorised on a pilot scale to produce Exiguobacterium sp GM010 pigment. Further, the pigments so produced were found to be non-toxic to Wistar rats, indicating its potential use as food additives and nutraceuticals.