Differences in Yields of Microbial Crude Protein from In Vitro Fermentation of Carbohydrates,DOI: http://dx.doi.org/10.3168/jds.S0022-0302(01)74699-1

Abstract

The yield of microbial crude protein (CP) from carbohydrate fermentations was examined using trichloroacetic acid (TCA) precipitation of batch cultures. The medium contained ammonium bicarbonate, casein acid hydrolysate, and cysteine hydrochloride as nitrogen sources. Isolated bermudagrass neutral detergent fiber (iNDF) and 60:40 blends of iNDF and sucrose (Suc), citrus pectin (Pec), or corn starch (Sta) ∼375 mg of substrate organic matter/vial) were fermented in vitro in two separate fermentation runs with mixed ruminal microbes. Three fermentation tubes for each substrate were destructively sampled at 0, 4, 8, 12, 16, 20, and 24 h. Fermented samples were precipitated at a concentration of 19.4% TCA, and filtered to collect unfermented iNDF and precipitate. Collected residues were analyzed for CP as Kjeldahl N × 6.25. Microbial CP (TCACP) was estimated as TCA-precipitated CP corrected for the TCA-precipitated CP content of substrates at 0 h, and the mean of fermentation blanks from each hour. Medium pH did not decline below 6.49 in any fermentation tube. Comparisons of maximal yields based on the hour in which the measured mean yield was greatest for each substrate in each fermentation indicated that Sta > Suc = Pec > iNDF (P 

Yes, microbial intracellular protein can be precipitated by TCA. Please see the attached pdf.

Yes. Microbial protein is charaterized as TCA ppt protein

Microbial prtein is called as tca ppt protein in cncps system of classification