Encapsulating Viability of Multi-strain Lactobacilli as Potential Probiotic in Pigs.

Important aspects of the selection of probiotics to be used for mixing in animal feed include host species specificity and probiotic cell survival during production and storage of their products. The research was to screen and investigate some probiotic properties of lactic acid bacteria (LAB) isolated from pig fecal samples. One hundred and thirty-eight representative LAB isolates, which were isolated from 51 pig fecal samples, were tested for acid and bile tolerance, antimicrobial susceptibility, antibacterial activity, potential adhesion to the cell surface, and survival rates when stored in varied microencapsulation forms: freeze-dried, spray-dried, and micro-beads. The antibacterial activity results of the ten LAB isolates, which were acid- (pH 2, 3 h) and bile- (50% (v/v) fresh pig bile, 8 h) tolerant and suitable for resisting the five antibiotics commonly used for treating pig infections with pathogenic indicator strains, showed that three isolates (L21, L80, L103) had strong inhibition to Escherichia coli, Salmonella group B, and Salmonella group D using co-culturing and agar spot assays. The three isolates had high hydrophobicity (65-73%) and did not show antagonistic growth against each other. All three selected isolates had greater than 80% survival in freeze-dried and micro-bead forms at 25-30 °C after 2 days of storage (80.4-86.75%, 7.31-7.89 log CFU/ml). Sequence analysis of the 16S rRNA genes demonstrated that the three isolates belong to Lactobacillus plantarum (strain L21 and strain L80) and L. paraplantarum (strain L103). The single and multiple strains of these bacteria may have potential use as probiotics in pig diets.

In vitro and in vivo evaluation of protein quality of enzymatic treated feather meals.

Feeding trials were designed to evaluate the nutritive value of feather meal treated by K6 and K82 keratinase. There were five treatments in feather meal preparation: CFM (non-enzymatically treated feather meal), K6FM (K6 keratinase treated feather meal), K82FM (K82 keratinase treated feather meal), K6:K82FM [K6 and K82 keratinase (5:1) treated feather meal] and CMFM (commercial enzyme treated feather meal). The pepsin digestibility of CFM (70 %) and CMFM (68 %) was significantly higher than K6FM (60 %), K82FM (61 %) and K6:K82FM (63 %). Total amino acid content of K82FM (89.65/100 g) was the highest compared with the other treatments. The nutrient digestibility of the feather meals was determined for broiler chicks between 21 and 27 days old. The apparent nitrogen retention of K82FM (85.82 %) and K6FM (77.31 %) was significantly higher than K6:K82FM (55.42 %), CMFM (45.70 %) and CFM (48.16 %). The apparent metabolisable energy (AMEn) was not significantly different between the feather meal treatments, although K82FM, K6FM and K6:K82FM showed AMEn higher than CMFM and CFM. The results indicated that both K6 and K82 keratinase had a positive effect on the protein quality of the feather meal produced by the enzymatic-hydrothermal method.

Expression and characterization of Aspergillus thermostable phytases in Pichia pastoris.

Two thermostable phytases were identified from Thai isolates of Aspergillus japonicus BCC18313 (TR86) and Aspergillus niger BCC18081 (TR170). Both genes of 1404 bp length, coding for putative phytases of 468 amino acid residues, were cloned and transferred into Pichia pastoris. The recombinant phytases, r-PhyA86 and r-PhyA170, were expressed as active extracellular, glycosylated proteins with activities of 140 and 100 U mL(-1), respectively. Both recombinant phytases exhibited high affinity for phytate but not for p-nitrophenyl phosphate. Optimal phytase activity was observed at 50 degrees C and pH 5.5. High thermostability, which is partly dependent on glycosylation, was demonstrated for both enzymes, as >50% activity was retained after heating at 100 degrees C for 10 min. The recombinant phytases also exhibited broad pH stability from 2.0 to 8.0 and are resistant to pepsin. In vitro digestibility tests suggested that r-PhyA86 and r-PhyA170 are at least as efficient as commercial phytase for hydrolyzing phytate in corn-based animal feed and are therefore suitable sources of phytase supplement.