Growth Of Lactobacillus Strains Research Articles

Effect of Acid and Oxidation Degradation of Gum Arabic on the Growth of Lactobacillus Strains

Gum arabic consisted of polysaccharides that has the potential to be converted into oligosaccharides through degradation. Thus, this study aimed to determine the effect of gum arabic degradation on the growth of two Lactobacillus probiotic strains. Two types of gum arabic (Acacia senegaland Acacia seyal) were subjected to trifluoroacetic acid (TFA) and oxidation degradation. TFA degradation produced a significantly higher (p<0.05) degree of degradation for A. senegal (67.6%) and A. seyal (62.87%) compared to oxidation method for A. senegal (36.49%) and A. seyal (39.37%). Thus, TFA degradation was selected as the degradation method. The TFA treated gum arabic was used as growth medium for two types of probiotic strains namely, Lactobacillus plantarum and Lactobacillus reuteri. Results showed that OD of TFA treated gums from A. senegal(1.390) and A. seyal (1.330) was significantly higher (p<0.05) compared to untreated samples innoculated with Lactobacillus plantarum. Similarly, CDM of TFA treated gums innoculated with Lactobacillus plantarum for A. senegal(1.150 g/L) and A. seyal(1.050 g/L) was also significantly higher (p<0.05) compared to untreated samples. Using treated gum, the growth (OD and CDM) of Lactobacillus reuteri was significantly higher (p<0.05) compared to untreated gum. Prebiotic Index (Ipreb) of both types of treated gum arabic was significantly improved (p<0.05) compared to untreated samples. In conclusion, treating gum arabic from both Acacia senegaland Acacia seyal with TFA produced samples which were more favourable for the growth of Lactobacillus plantarum and Lactobacillus reuteri strains with significantly increased (p<0.05) Ipreb.

A kinetic analysis of the aflatoxin detoxification potential of lactic acid bacteria in Terxine (a cereal-based food)

Aflatoxin B1 (AFB1) is a hazardous component that can seriously threaten the public health. Terxine is a component used in traditional soup and found in the western mountainous regions of Iran. Several microorganisms have been reported to bind or degrade aflatoxins (AFs) in foods and feeds. This research aimed to investigate the effect of Terxine fermentation byLactobacillus plantarumstrains AF1 and LU5 on AFB1. Fermentation was carried out, and pH, lactic acid and AFB1 amount and microbial count were further determined. In addition, the kinetic experimental data of AFB1 by L. plantarumAF1 and LU5 (obtained at 37°C) were fitted to the zero-order, first-order and parabolic diffusion models. According to the coefficient of determination (R2) and root mean square of errors (RMSE), the zero-order model best described AF degradation. The growth of Lactobacillus strains was increased by the rise in the fermentation time; in this regard, the number of L. plantarum AF1 increased from 4.2 to 5.1 log cfu/g and that of L. plantarum LU5 increased from 4.1 to 5.2 log cfu/g in the first 8h, reaching 7.2 and 7.4 log cfu/g in the next 8h, respectively. The results also showed that the amount of lactic acid increased whereas the pH value decreased during the 24h fermentation. Both microorganisms reduced the amount of AFB1 while L. plantarum AF1 was more effective. Therefore, L. plantarumstrains AF1 and LU5 can be effectively used to reduce AFB1 in fermented foods.

Effect of prebiotic oligosaccharides on growth of Lactobacillus strains used as a probiotic for chickens

In the present study, the effect of 10 commercially available oligosaccharides on the growth of 11 Lactobacillus strains, which were isolated from the gastrointestinal tract of chickens and have been used as a multistrain probiotic for chickens, was evaluated in vitro. The utilization of oligosaccharides was highly variable among the 11 Lactobacillus strains and considerable strains differences (P < 0.05) were observed. Isomaltooligosaccharides (IMO) supported good growth for all the 11 Lactobacillus strains, followed by galactooligosaccharides (GOS), gentiooligosaccharides (GTO) and fructooligosaccharides (FOS). Oligosaccharides such as Raftilose L60, Raftilose P95, Raftiline LS, and mannanoligosaccharides (MOS) were poorly utilized by all the Lactobacillus strains. Growth kinetics study also showed variations in the specific growth rates and growth patterns of four representative Lactobacillus species on four selected oligosaccharides. The highest specific growth rate was demonstrated by Lactobacillus salivarius I 24 on FOS. The results showed that the ability of the 11 probiotic Lactobacillus strains to utilize oligosaccharides could be both strain and substrate specific, which demonstrates the importance of selecting suitable prebiotic oligosaccharides for the preparation of synbiotics.

A strategy to prevent the occurrence of Lactobacillus strains using lactate-tolerant yeast Candida glabrata in bioethanol production

Contamination of Lactobacillus sp. in the fermentation broth of bioethanol production decreases ethanol production efficiency. Although the addition of lactate to the broth can effectively inhibit the growth of Lactobacillus sp., it also greatly reduces the fermentation ability of Saccharomyces cerevisiae. To overcome this conflict, lactate-tolerant yeast strains were screened. Candida glabrata strain NFRI 3164 was found to exhibit both higher levels of lactate tolerance and fermentation ability. Co-cultivation of C. glabrata was performed with Lactobacillus brevis and Lb. fermentum, which were reported as major contaminating bacteria during bioethanol production, in culture medium containing 2% lactate. Under these culture conditions, the growth of Lactobacillus strains was greatly inhibited, but the ethanol production of C. glabrata was not significantly affected. Our data show the possibility of designing an effective fuel ethanol production process that eliminates contamination by Lactobacillus strains through the combined use of lactate addition and C. glabrata.