BACTERIAL FERMENTATION PROCESS FOR EXTRACTION OF PROTEIN HYDROLYSATE FROM YEAST BIOMASS

摘要

Agro-industries generate a large variety of wastes and protein rich substances as by-products. Protein wastes when recycled and reprocessesed yields higher value products that can be utilized as feed supplements in birds, animals, fish and also for plants to enhance the growth and development. Distillery yeast biomass is one such by-product having high protein content of upto 40-60% which remains unused and unexplored. Microbial deproteinization was done using distillery yeast biomass as substrate for the extraction of protein in the form of amino acids by inoculating proteolytic bacterial culture, Bacillus tnegaterium PB4. The isolate PB4 produced maximum protease of 420.5 U ml-1. The deproteinization efficiency was 83.50% with optimum glucose concentration (1.0%), substrate concentration (5.0%), pH (7.0) and fermentation time (96 hours). At the end of fermentation, the fermented liquid was filtered which resulted in the protein hydrolysates with a pH of 4.72. Amino acid analysis revealed that protein hydrolysate was rich in 7 essential amino acids and 4 non-essential amino acids. The effect of protein hydrolysates on the growth and development of bhendi crop plant, broilers, piglets and fishlings were studied. It was found that the foliar application of protein hydrolysates performed well over the soil application in bhendi by enhancing the growth viz., plant height (92.54 cm), root length (72.56 cm) leaf area (704.55 cm2 plant-1) and chlorophyll content (3.12 mg g-1). Yield parameters like fruit length, fruit weight, number of fruits and yield recording 12.25 cm, 9.84 g, 8.20 plant-1 and 76.03 g plant-1, respectively over control. Protein hydrolysates when supplemented with feed to broilers at 25% level, recorded highest body weight (2696.7 g) which was 574.6 g increase over control at the end of 6 weeks (complete broiler cycle). The organoleptic studies of the broiler meat fed with protein hydrolysates had better quality. The effect of protein hydrolysates as feed supplement in piglets also performed well over control. Over a period of ten weeks, animals that received 50% as feed supplement recorded the maximum weight gain of 5.17 kg over control. In fishlings, the effect of protein hydrolysates on body weight was upto 43.37% increase over control. The microbially obtained protein hydrolysates from distillery yeast biomass is an economically viable product which could be used as feed additive for broilers, pigs ,fish and as an effective growth booster for bhendi crop systems.