Biological Effects of Feeding Single Cell Protein Produced byPseudomonas methylotrophafrom Methanol to Chickens

Nutritional and functional values of lysed Corynebacterium glutamicum cell mass for intestinal health and growth of nursery pigs

The objective was to determine the nutritional and functional values of lysed Corynebacterium glutamicum cell mass (CGCM) as a protein supplement and a source of cell wall fragments supporting the growth and intestinal health of nursery pigs. Thirty-two pigs (21 d of age) were allotted to four treatments (n = 8) based on the randomized block design with sex and initial body weight (BW) as blocks. The main effect was the dietary supplementation of lysed CGCM (0, 0.7, 1.4, and 2.1%) replacing blood plasma and fed in two phases (10 and 11 d, respectively). Feed intake and BW were measured at the end of each phase. Pigs were euthanized on day 21 to collect jejunal tissue and mucosa to evaluate intestinal health. Ileal digesta were collected to measure the apparent ileal digestibility of nutrients in diets. Data were analyzed using Proc Mixed and Reg of SAS. Increasing daily intake of CGCM increased (linear; P < 0.05) ADG of pigs. Increasing CGCM supplementation affected (quadratic; P < 0.05) the relative abundance of Lactobacillaceae (minimum: 26.4% at 1.2% CGCM), Helicobacteraceae (maximum: 29.3% at 1.2% CGCM), and Campylobacteraceae (maximum: 9.0% at 1.0% CGCM). Increasing CGCM supplementation affected (quadratic; P < 0.05) the concentrations of immunoglobulin G (maximum: 4.94 µg/mg of protein at 1.0% CGCM) and protein carbonyl (PC; maximum: 6.12 nmol/mg of protein at 1.1% CGCM), whereas linearly decreased (P < 0.05) malondialdehyde (MDA) in the proximal jejunal mucosa. Increasing CGCM supplemention affected (quadratic; P < 0.05) intestinal enterocyte proliferation rate (maximum: 13.3% at 1.0% CGCM), whereas it did not affect intestinal morphology and the nutrient digestibility. In conclusion, supplementing 1.0% to 1.2%, reducing blood plasma supplementation by 0.7% to 0.9%, respectively, increased potential pathogenic microbiota associated in the jejunal mucosa resulting in increased immune response, enterocyte proliferation, and PC concentration. However, supplementing diets with 2.1% CGCM, replacing 1.5% blood plasma, improved growth performance, and reduced MDA without affecting nutrient digestibility, intestinal morphology, and microbiota in the jejunal mucosa. In this study, based on the polynomial contrast, supplementing 1.0% to 1.2% CGCM suppressed the benefits from blood plasma, whereas supplementing 2.1% CGCM showed functional benefits of CGCM with similar effects from blood plasma supplementation.

Immunotoxicity of nucleic acid reduced BioProtein--a bacterial derived single cell protein--in Wistar rats

BioProtein is a single cell protein produced by a mixed methanotrophic and heterotrophic bacteria culture using natural gas as energy source, which has been approved for animal feed. BioProtein contains a large amount of nucleic acids making the product less suitable for human consumption, therefore, a nucleic acid reduced variant (NABP) has been developed by the manufacturer. The purpose of the present study was to establish the safety of NABP in a subchronic toxicity rat study. Groups of 10 male and 10 female Wistar rats were fed diets containing 0, 6, 12 or 24% NABP for 13 weeks. Feeding NABP induced a humoral immune response and proliferation of phagocytic cell lines, mainly macrophages. The humoral response involved induction of NABP specific IgM and IgG. The proliferation of phagocytic cells involved increase of the white blood cell count of all dosed female groups. Males showed the same tendency, although, not statistically significant (P=0.09). The subsets of cells identified as neutrophils and eosinophils were increased and lymphocytes decreased. The histopathological examination revealed histiocytosis and accumulation of foamy macrophages in the mesenteric lymph nodes, hyperplasia of Kupffer cells in the liver, increased granulopoiesis in spleen and bone marrow, and infiltration of lamina propria of the large intestine with eosinophilic granulocytes. The most consistent and pronounced changes were observed in the highest dose group, but even at the lowest dose level some of the changes were present. Accordingly, a no-observed-effect level could not be established based on this study.

Single-cell protein: current status and future prospects

The consumption of microorganisms by man and animals is not a revolutionary new idea. For thousands of years man has consumed, either intentionally or unintentionally, such products as alcoholic beverages, cheeses, yogurt, and soya sauce and, along with these products, the microbial biomass responsible for their production. The rapid growth rate and high protein content of microbes and their ability to utilize inexpensive feedstocks as sources of carbon and energy for growth have made microorganisms prime candidates for use as human food and animal feed protein supplements. Yet, in spite of their promise, only a limited number of commercial-scale, single-cell protein (SCP) processes have been seen. Recently, with the advent of recombinant DNA technology a rebirth of interest in SCP has resulted. This review analyzes the answers to two questions: (1) how far have we come?; and (2) what impact, if any, will the new biotechnologies have in this field?