Selection of Bacillus subtilis US191 as a mannanase-producing probiotic candidate.

ß-Mannanases are crucial enzymes for the breakdown of mannans. As Mannans are being considered as antinutritional factors in poultry production, the search for mannanase-producing probiotic bacteria is now attracting considerable attention as a strategy to enhance nutrients bioavailability. Five soil born Bacilli (US134, US150, US176, US180, and US191) were selected for their ability to produce extracellular ß-mannanases that were biochemically characterized. The probiotic properties of these strains were determined to assess their potential as animal feed supplements. Bacillus subtilis US191 was shown to be sensitive to all antibiotics tested, to inhibit growth of the bacterial pathogens tested, and to produce a thermostable ß-mannanase. It exhibited a notable acid and bovine bile tolerance and high ability to form biofilm. These features may favor its adherence to the intestinal epithelial cells allowing its survival and persistence in the digestive tract. Furthermore, our study revealed that US191 was among the strains showing the highest ability to digest wheat dry matter in vitro when compared to the commercial feed additive Rovabio® Max. Altogether, our findings suggest that the ß-mannanase producer B.subtilis US191 is a promising probiotic candidate for the feed industry.

Assessment of the potential of the multi-enzyme producer Bacillus amyloliquefaciens US573 as alternative feed additive.

BACKGROUND: Recently, probiotics have increasingly been used as feed additives in poultry diets as an alternative to antibiotic growth promoters fostering resistance development. RESULTS: This study was aimed at assessing the potential of Bacillus amyloliquefaciens US573 as a direct-fed microbial. The US573 strain was found to be free of harmful enzymatic activities and sensitive to antibiotics. In addition, it showed a good acid and bovine bile tolerance, high adhesion efficacy to chicken enterocytes, and an ability to form biofilms, which may favor its survival and persistence in the animal gastrointestinal tract. Moreover, besides the previously described extremely salt-tolerant and highly thermostable phytase, the US573 strain secretes xylanase, ß-glucanase and amylase activities useful in neutralizing antinutritional factors and maximizing the absorption of nutrients. The secretion of such enzymes may be responsible for the good performance of the US573 isolate in the digestibility of wheat in vitro. Indeed, using the vegetative cells, a yield of wheat dry matter digestibility of approximately 48% was achieved, which is slightly lower than the commercial feed additive Rovabio used as a reference (56.73% digestibility). CONCLUSION: The obtained results illustrate the potential of US573 strain as a promising direct-fed microbial candidate for application in the poultry industry. © 2017 Society of Chemical Industry.

Evidence for the negative regulation of phytase gene expression in Streptomyces lividans and Streptomyces coelicolor.

Sco7697, a gene encoding a phytase, enzyme able to degrade phytate (myo-inositol 1,2,3,4,5,6-hexakis phosphate), the most abundant phosphorus storing compound in plants is present in the genome of S. coelicolor, a soil born bacteria with a saprophytic lifestyle. The expression of this gene was previously shown to be induced in conditions of Pi limitation by the response regulator PhoP binding to an operator sequence, the PHO box, located upstream of the -35 promoter sequence. A close examination of the promoter region of sco7697 revealed the presence of another putative operator site, a Direct Repeat (DR), located downstream of the -10 promoter sequence. In order to determine whether this DR played a role in regulation of sco7697 expression, different variants of the phytase gene promoter region were transcriptionally fused to the ß-glucuronidase reporter gene (GUS). As expected, deletion of the PHO box led to abolition of sco7697 induction in conditions of Pi limitation. Interestingly, alteration of the DR correlated with a dramatic increase of GUS expression but only when PhoP was present. These results demonstrated that this DR is the site of strong negative regulation by an unknown repressor. The latter would impede the necessary activation of phytase expression by PhoP.

Cloning and characterization of the first actinomycete ß-propeller phytase from Streptomyces sp. US42.

A gene encoding an extracellular phytase was cloned for the first time from an Actinomycete, Streptomyces sp. US42 and sequenced. The sequence of this gene revealed an encoded polypeptide (PHY US42) exhibiting one and six residues difference with the putative phytases of Streptomyces lividans TK24 and Streptomyces coelicolor A3(2), respectively. The molecular modeling of PHY US42 indicated that this phytase belongs to the group of ß-propeller phytases that are usually calcium-dependent. PHY US42 was purified and characterized. Its activity was calcium-dependent and maximal at pH 7 and 65 °C. The enzyme was perfectly stable at pH ranging from 5 to 10 and its thermostability was greatly enhanced in the presence of calcium. Indeed, PHY US42 maintained 80% of activity after 10 min of incubation at 75 °C in the presence of 5 mM CaCl2 . PHY US42 was also found to exhibit high stability after incubation at 37 °C for 1 h in the presence of bovine bile and digestive proteases like of pepsin, trypsin, and chymotrypsin. Considering its biochemical properties, PHY US42 could be used as feed additive in combination with an acid phytase for monogastric animals.

Over-expression of the bacterial phytase US417 in Arabidopsis reduces the concentration of phytic acid and reveals its involvement in the regulation of sulfate and phosphate homeostasis and signaling.

Phytic acid (PA) is the main phosphorus storage form in plant seeds. It is recognized as an anti-nutrient for humans and non-ruminant animals, as well as one of the major sources of phosphorus that contributes to eutrophication. Therefore, engineering plants with low PA content without affecting plant growth capacity has become a major focus in plant breeding. Nevertheless, lack of knowledge on the role of PA seed reserves in regulating plant growth and in maintaining ion homeostasis hinders such an agronomical application. In this context, we report here that the over-expression of the bacterial phytase PHY-US417 in Arabidopsis leads to a significant decrease in seed PA, without any effect on the seed germination potential. Interestingly, this over-expression also induced a higher remobilization of free iron during germination. Moreover, the PHY-over-expressor lines show an increase in inorganic phosphate and sulfate contents, and a higher biomass production after phosphate starvation. Finally, phosphate sensing was altered because of the changes in the expression of genes induced by phosphate starvation or involved in phosphate or sulfate transport. Together, these results show that the over-expression of PHY-US417 reduces PA concentration, and provide the first evidence for the involvement of PA in the regulation of sulfate and phosphate homeostasis and signaling.

Lactobacillus plantarum TN627 significantly reduces complications of alloxan-induced diabetes in rats.

This study aimed to assess the potential of the probiotic strain Lactobacillus plantarum TN627 for preventing alloxan-induced diabetes in rats. The oral administration of this probiotic was noted to significantly improve the immunological parameters, protect the pancreatic tissues, and reduce the pancreatic and plasmatic α-amylase activities and level of plasma glucose in the treated as compared to the control group of rats. Furthermore, this probiotic treatment was observed to markedly reduce pancreatic and plasmatic lipase activities and serum triglyceride and LDL-cholesterol rates and to increase the level of HDL-Cholesterol. It also exerted efficient protective effects on the liver and kidney functions evidenced by significant decreases in serum aspartate transaminase, alanine transaminase, lactate dehydrogenase, and gamma-glutamyl transpeptidase activities, as well as creatinine and urea contents. Taken together, the findings indicate that L. plantarum TN627 exhibits attractive in vivo antidiabetic effects that may be helpful in preventing diabetic complications in adult rats.

Lactobacillus plantarum TN8 exhibits protective effects on lipid, hepatic and renal profiles in obese rat.

This study aimed to first investigate the immuno-modulatory effects of six newly isolated lactic acid bacteria (LAB) on the peripheral blood mononuclear cells (PBMC) of Wistar rats. Except for Lactobacillus plantarum TN8, all the other strains were noted to induce high levels of pro-inflammatory cytokine IL-12 and low levels of anti-inflammatory cytokine IL-10. The strains also generated low ratios of IL-10/IL-12 cytokine. Strain TN8 was, on the other hand, noted to induce an increase in anti-inflammatory IL-10 cytokine secretion rates and a decrease in pro-inflammatory IL-12, IFN-γ and TNF-α cytokine production. The oral administration of TN8 improved the hepatic and urinary functions of obese rats by inducing decreases (P < 0.05) in alanine amino transferase (ALAT), gamma glutamyl transferase (GGT), plasmatic triglycerides, total cholesterol concentrations, creatinine, urea, and body weight when compared to the control group of animals that underwent an increase in aspartate amino transferase (ASAT) and high density lipoprotein (HDL). Overall, the findings indicate that strain TN8 exhibited a number of attractive properties that might open new promising opportunities for the improvement of various parameters related to animal health performance and the avoidance of antibiotics and drugs as promoting factors.

Bacillus Species as Direct-Fed Microbial Antibiotic Alternatives for Monogastric Production.

Antibiotic growth promoters have been utilized for long time at subtherapeutic levels as feed supplements in monogastric animal rations. Because of their side-effects such as antibiotic resistance, reduction of beneficial bacteria in the gut, and dysbiosis, it is necessary to look for non-therapeutic alternatives. Probiotics play an important role as the key substitutes to antibacterial agents due to their many beneficial effects on the monogastric animal host. For instance, enhancement of the gut microbiota balance can contribute to improvement of feed utilization efficiency, nutrients absorption, growth rate, and economic profitability of livestock. Probiotics are defined as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host." They are available in diverse forms for use as feed supplements. Their utilization as feed additives assists in good digestion of feed ingredients and hence, making the nutrients available for promoting growth. Immunity can also be enhanced by supplementing probiotics to monogastrics diets. Moreover, probiotics can help in improving major meat quality traits and countering a variety of monogastric animals infectious diseases. A proper selection of the probiotic strains is required in order to confer optimal beneficial effects. The present review focuses on the general functional, safety, and technological screening criteria for selection of ideal Bacillus probiotics as feed supplements as well as their mechanism of action and beneficial effects on monogastric animals for improving production performance and health status.

Effects of Dietary Supplementation with Bacillus amyloliquefaciens US573 on Intestinal Morphology and Gut Microbiota of European Sea Bass.

Probiotics or direct-fed microbials (DFM) have proven strong potential for improving aquaculture sustainability. This study aims to evaluate the effects of dietary supplementation with the DFM Bacillus amyloliquefaciens US573 on growth performance, intestinal morphology, and gut microbiota (GM) of European sea bass. For this purpose, healthy fish were divided into two feeding trials in triplicate of 25 fish in each tank. The fish were fed with a control basal diet or a DFM-supplemented diet for 42 days. Results showed that, while no significant effects on growth performance were observed, the length and abundance of villi were higher in the DFM-fed group. The benefic effects of DFM supplementation included also the absence of cysts formation and the increase in number of goblet cells playing essential role in immune response. Through DNA metabarcoding analysis of GM, 5 phyla and 14 major genera were identified. At day 42, the main microbiome changes in response to B. amyloliquefaciens US573 addition included the significant decrease in abundance of Actinobacteria phylum that perfectly correlates with a decrease in Nocardia genus representatives which represent serious threat in marine and freshwater fish. On the contrary, an obvious dominance of Betaproteobacteria associated with the abundance in Variovorax genus members, known for their ability to metabolize numerous substrates, was recorded. Interestingly, Firmicutes, particularly species affiliated to the genus Sporosarcina with recent promising probiotic potential, were identified as the most abundant. These results suggest that B. amyloliquefaciens US573 can be effectively recommended as health-promoting DFM in European sea bass farming.

A new Lactobacillus plantarum strain, TN8, from the gastro intestinal tract of poultry induces high cytokine production.

This study aimed to determine the probiotic potential of 100 strains of Lactic Acid Bacteria (LAB) isolated from different intestinal segments of indigenous poultry in Tunisia. The strains were submitted to a battery of standard tests and criteria commonly used for determining their probiotic properties and attributes. The findings revealed that 19 of the isolates exhibited antimicrobial activity against 4 pathogenic bacteria, and that 4 (TN1, TN8, TN7, and TN13) showed good resistance to pH 3 and 5% bovine bile. Three isolates, namely TN1, TN8, and TN13, showed sensitivity to several antibiotics and were, therefore, selected for further enzymatic activity assays. Two isolates, namely TN1 and TN8, showed high efficacy of adhesion to chicken enterocytes. The cytokines released after stimulation by the two isolates showed high anti-inflammatory profiles, with an increased rate of Interleukin-10 (IL-10) production for the TN8 strain. Showing the highest performance, TN8 was submitted to 16S rRNA gene sequencing, which revealed that the strain was of the species Lactobacillus plantarum. Overall, the findings indicate that the Lactobacilli from poultry intestine has a number of promising properties that make it candidate for application as a probiotic additive in poultry industry.

Secretion of cyclodextrin glucanotransferase in E. coli using Bacillus subtilis lipase signal peptide and optimization of culture medium.

The cyclodextrin glycosyltransferase (CGTase) of Paenibacillus pabuli US132 was fused to the secretive lipase signal peptide of B. subtilis. This leads to an efficient secretion of the recombinant enzyme into the culture medium of E. coli as an active and soluble form contrasting with the native construction leading to a periplasmic production. In order to enhance the yield of CGTase production, an experimental design methodology was applied for the optimization of the culture composition. Hence, the media components were submitted to preliminary screening using a Plakett-Burman design. The concentrations of the major operating ones were then optimized to enhance the secretion of CGTase using response surface methodology. The findings revealed that concentrations of 0.5% potato starch, 3% yeast extract, 3% tryptone, 1.5% casein hydrolysate, 0.5% NaCl, 0.2% KH2PO4, and 0.02% MgSO4 were the optimal conditions for CGTase production. The experimental value (9.43 U/mL) obtained for CGTase activity was very close to the predicted value (9.27 U/mL).

Towards understanding the antagonistic activity of phytic acid against common foodborne bacterial pathogens using a general linear model.

The increasing challenge of antibiotic resistance requires not only the discovery of new antibiotics, but also the development of new alternative approaches. Therefore, in the present study, we investigated for the first time the antibacterial potential of phytic acid (myo-inositol hexakisphosphate, IP6), a natural molecule that is 'generally recognized as safe' (FDA classification), against the proliferation of common foodborne bacterial pathogens such as Listeria monocytogenes, Staphylococcus aureus and Salmonella Typhimurium. Interestingly, compared to citric acid, IP6 was found to exhibit significantly greater inhibitory activity (P<0.05) against these pathogenic bacteria. The minimum inhibitory concentration of IP6 varied from 0.488 to 0.97 mg/ml for the Gram-positive bacteria that were tested, and was 0.244 mg/ml for the Gram-negative bacteria. Linear and general models were used to further explore the antibacterial effects of IP6. The developed models were validated using experimental growth data for L. monocytogenes, S. aureus and S. Typhimurium. Overall, the models were able to accurately predict the growth of L. monocytogenes, S. aureus, and S. Typhimuriumin Polymyxin acriflavine lithium chloride ceftazidime aesculin mannitol (PALCAM), Chapman broth, and xylose lysine xeoxycholate (XLD) broth, respectively. Remarkably, the early logarithmic growth phase of S. Typhimurium showed a rapid and severe decrease in a period of less than one hour, illustrating the bactericidal effect of IP6. These results suggest that IP6 is an efficient antibacterial agent and can be used to control the proliferation of foodborne pathogens. It has promising potential for environmentally friendly applications in the food industry, such as for food preservation, food safety, and for prolonging shelf life.

Optimization of ß-mannanase production by Bacillus subtilis US191 using economical agricultural substrates.

The Bacillus subtilis US191 strain producing highly thermostable ß-mannanase was previously selected as potential probiotic candidate for application as feed supplement in poultry industry. Initially, the level of extracellular ß-mannanase production by this strain was 1.48 U ml-1 . To improve this enzyme titer, the present study was undertaken to optimize the fermentation conditions through experimental designs and valorization of agro-industrial byproducts. Using the Plackett-Burman design, in submerged fermentation, a set of 14 culture variables was evaluated in terms of their effects on ß-mannanase production. Locust bean gum (LBG), soymeal, temperature, and inoculum size were subsequently optimized by response surface methodology using Box-Behnken design. Under optimized conditions (1 g L-1 LBG, 8 g L-1 soymeal, temperature of 30°C and inoculum size of 1010 CFU ml-1 ), a 2.59-fold enhancement in ß-mannanase titer was achieved. Next, to decrease the enzyme production cost, the effect of partial substitution of LBG (1 g L-1 ) by agro-industrial byproducts was investigated, and a Taguchi design was applied. This allowed the attaining of a ß-mannanase production level of 8.75 U ml-1 in presence of 0.25 g L-1 LBG, 5 g L-1 of coffee residue powder, 5 g L-1 of date seeds powder, and 5 g L-1 of prickly pear seeds powder as mannans sources. Overall, a 5.91-fold improvement in ß-mannanase production by B. subtilis US191 was achieved.

Characterization of the mineral phosphate solubilizing activity of Serratia marcescens CTM 50650 isolated from the phosphate mine of Gafsa.

The mineral phosphate solubilizing (MPS) ability of a Serratia marcescens strain, namely CTM 50650, isolated from the phosphate mine of Gafsa, was characterized on a chemically defined medium (NBRIP broth). Various insoluble inorganic phosphates, including rock phosphate (RP), calcium phosphate (CaHPO(4)), tri-calcium phosphate (Ca(3)(PO(4))(2)) and hydroxyapatite were tested as sole sources of phosphate for bacterial growth. Solubilization of these phosphates by S. marcescens CTM 50650 was very efficient. Indeed, under optimal conditions, the soluble phosphorus (P) concentration it produced reached 967, 500, 595 and 326 mg/l from CaHPO(4), Ca(3)(PO(4))(2), hydroxyapatite and RP, respectively. Study of the mechanisms involved in the MPS activity of CTM 50650, showed that phosphate solubilization was concomitant with significant drop in pH. HPLC-analysis of culture supernatants revealed the secretion of gluconic acid (GA) resulting from direct oxidation pathway of glucose when the CTM 50650 cells were grown on NBRIP containing glucose as unique carbon source. This was correlated with the simultaneous detection by PCR for the first time in a S. marcescens strain producing GA, of a gene encoding glucose dehydrogenase responsible for GA production, as well as the genes pqqA, B, C and E involved in biosynthesis of its PQQ cofactor. This study is expected to lead to the development of an environmental-friendly process for fertilizer production considering the capacity of S. marcescens CTM 50650 to achieve yields of P extraction up to 75% from the Gafsa RP.

Gene cloning and characterization of a thermostable phytase from Bacillus subtilis US417 and assessment of its potential as a feed additive in comparison with a commercial enzyme.

An extracellular phytase from Bacillus subtilis US417 (PHY US417) was purified and characterized. The purified enzyme of 41 kDa was calcium-dependent and optimally active at pH 7.5 and 55 degrees C. The thermal stability of PHY US417 was drastically improved by calcium. Indeed, it recovered 77% of its original activity after denaturation for 10 min at 75 degrees C in the presence of 5 mM CaCl2, while it retained only 22% of activity when incubated for 10 min at 60 degrees C without calcium. In addition, PHY US417 was found to be highly specific for phytate and exhibited pH stability similar to Phyzyme, a commercial phytase with optimal activity at pH 5.5 and 60 degrees C. The phytase gene was cloned by PCR from Bacillus subtilis US417. Sequence analysis of the encoded polypeptide revealed one residue difference from PhyC of Bacillus subtilis VTTE-68013 (substitution of arginine in position 257 by proline in PHY US417) which was reported to exhibit lower thermostability especially in the absence of calcium. With its neutral pH optimum as well as its great pH and thermal stability, the PHY US417 enzyme presumed to be predominantly active in the intestine has a high potential for use as feed additive.

Fate of the sblA transcript in Streptomyces lividans and Escherichia coli.

In Streptomyces lividans, the tight temporal regulation of the transient expression of the sblA gene was shown to involve an operator-like sequence located on the sblA transcript. This operator-like structure constitutes a stem-loop structure containing a Shine/Dalgarno-like sequence. Its destruction, by site directed mutagenesis, led to an enhancement of sblA expression. This structure thus plays a negative role in the regulation of sblA expression and might be involved in the regulation of the specific degradation of the sblA transcript. In this issue, the fates of the sblA transcript, in S. lividans and in Escherichia coli, were compared. Analysis of the decay of the sblA transcript revealed that, in both species, the sblA transcript was cleaved just behind the stem-loop structure by an RNAse E-like activity. In E. coli, three discrete products resulting from the cleavage of the full-length transcript by the RNAase E at another site, located 282 nucleotides downstream of the stem-loop structure, were detected whereas only one processed product, corresponding to the 5' end of the gene, was detected in S. lividans. These differences in the mode of degradation of the sblA transcript in S. lividans and E. coli are discussed.

Characterization of an l-arabinose isomerase from the Lactobacillus plantarum NC8 strain showing pronounced stability at acidic pH.

Gene araA encoding the l-arabinose isomerase (l-AI) from Lactobacillus plantarum NC8 was cloned and expressed in Escherichia coli. It encodes a polypeptide of 474 residues having 55% identities with l-AIs from Bacillus stearothermophilus US100 and Thermus sp. IM6501. The active form of the purified recombinant l-AI NC8 enzyme is a hexamer composed of six identical 55-kDa subunits. The purified enzyme was optimally active at 60 degrees C and pH 7.5. It required divalent cations such as Co(2+) and Mn(2+) for maximal activity and thermostability. The l-AI NC8 was exceptionally active and stable at acidic pH. Indeed, it exhibited 68% of its maximal activity at pH 5.5 and retained 89% of activity after a 24-h incubation at pH 5. The apparent K(m) values of the enzyme for l-arabinose and d-galactose were 43.4 and 69.7 mM, respectively, and its catalytic efficiency was c. 10-fold higher for the physiological substrate l-arabinose (15.5 mM(-1) min(-1)) than d-galactose (1.6 mM(-1) min(-1)). The bioconversion yield of d-galactose to d-tagatose by the purified l-AI NC8 after 6 h at 60 degrees C was 30%.

Mineral phosphate solubilization by Streptomyces sp. CTM396 involves the excretion of gluconic acid and is stimulated by humic acids.

The actinomycetes isolates (128) which were taken from agricultural soil samples and collected near a rock phosphate processing unit were screened for mineral phosphate-solubilizing (MPS) ability. A significant MPS activity was observed for 30 isolates on various phosphate sources when grown in the National Botanical Research Institute's phosphate broth. CTM396 and CTM397 strains which showed the highest MPS abilities were identified by 16S rDNA sequencing as members of the genus Streptomyces. Their MPS activity was proved to be concomitant with a drop in pH due to the secretion of gluconic acid (GA). This was correlated with the simultaneous detection by PCR of genes gdh [encoding the glucose dehydrogenase (GDH) responsible for GA production from glucose] and pqq (involved in biosynthesis of the pyrroloquinoline quinone cofactor of GDH), as well as the highlighting of GHD enzyme activity, for the first time in a Streptomyces sp. strain producing GA. Furthermore, the 0.05% of humic acids proved to have a stimulatory effect on the growth and the ability of CTM396 to solubilize Gafsa rock phosphate. According to this study, it is possible to use humic acids and Gafsa rock phosphate in association with spores of ad hoc Streptomyces strains as natural and efficient amendments to improve plant growth with no need of costly and pollutant transformation of Gafsa rock phosphate.

Characterization of an extremely salt-tolerant and thermostable phytase from Bacillus amyloliquefaciens US573.

The extracellular phytase produced by the Bacillus amyloliquefaciens US573 strain, isolated from geothermal soil located in Southern Tunisia was purified and characterized. This calcium-dependent and bile-stable enzyme (PHY US573) was optimally active at pH 7.5 and 70 °C. It showed a good stability at pH ranging from 4 to 10, and especially, an exceptional thermostability as it recovered 50 and 62% of activity after heating for 10 min at 100 and 90 °C, respectively. In addition, PHY US573 was found to be extremely salt-tolerant since it preserved 80 and 95% of activity in the presence of 20 g/l of NaCl and LiCl, respectively. The gene corresponding to PHY US573 was cloned. It encodes a 383 amino acids polypeptide exhibiting 99% identity with the highly thermostable phytases from Bacillus sp. MD2 and B. amyloliquefaciens DS11 (3 and 5 residues difference, respectively), suggesting the existence of common molecular determinants responsible for their remarkable heat stability. Overall, our findings illustrated that in addition to its high potential for application in feed industry, the salt tolerance of the PHY US573 phytase, may represent an exciting new avenue for improvement of phosphorus-use efficiency of salt-tolerant plants in soils with high salt and phytate content.

Effects of Lactobacillus plantarum immobilization in alginate coated with chitosan and gelatin on antibacterial activity.

The present study aimed to investigate and evaluate the efficiency of immobilizing the Lactobacillus plantarum TN9 strain in alginate using chitosan and gelatin as coating materials, in terms of viability and antibacterial activity. The results indicate that maximum concentrations of L. plantarum TN9 strain were produced with 2% sodium alginate, 10(8)UFC/ml, and 1M calcium chloride. The viability and antibacterial activity of the L. plantarum TN9 cultures before and after immobilization in alginate, chitosan-coated alginate, and gelatin-coated alginate, were studied. The findings revealed that the viability of encapsulated L. plantarum could be preserved more than 5.8 log CFU/ml after 35 day of incubation at 4 °C, and no effects were observed when gelatin was used. The antibacterial activity of encapsulated L. plantarum TN9 against Gram-positive and Gram-negative pathogenic bacteria was enhanced in the presence of chitosan coating materials, and no activity was observed in the presence of gelatin. The effects of catalase and proteolytic enzymes on the culture supernatant of L. plantarum TN9 were also investigated, and the results suggested that the antibacterial activity observed was due to the production of organic acids. Taken together, the findings indicated that immobilization in chitosan enhanced the antibacterial activity of L. plantarum TN9 against several pathogenic bacteria. This encapsulated strain could be considered as a potential strong candidate for future application as an additive in the food and animal feed industries.