Utilisation of tomato pomace as a substrate for the production of vitamin B12--a preliminary appraisal

The cellulose fraction in tomato pomace was hydrolysed using Trichoderma reesei, and the resultant sugars were fermented with Propionibacterium shermanii to produce vitamin B12. A multifactorial experiment revealed that aeration of the culture of T. reesei gave substantial improvements in cellulase activity as did higher concentrations of available nitrogen, but a rapid drop in pH appeared to inhibit extensive hydrolysis; after 14 days, the maximum level of cellulose degradation was only 34.4% of the total available, and the highest level of reducing sugars achieved was 15 g l(-1). When flasks with the latter concentration of reducing sugars were inoculated with P. shermanii, 11.1 mg l(-1) of B12 were produced under optimum conditions. If the degree of hydrolysis of the cellulose could be increased, then sufficient vitamin B12 might be generated to justify extraction but, even if purification does not prove to be economically feasible, a fermented tomato pomace (dried) with 50-55 mg kg(-1) or more of B12 could prove a useful feedstuff for animals.