Effects of Phage Cocktail, Probiotics, and Their Combination on Growth Performance and Gut Microbiota of Broiler Chickens.

Phages, which are often used therapeutically, have begun to receive interest as alternatives to antibiotic growth promoters (AGPs) for enhancing chicken growth. Another option that has been extensively studied as a growth promoter in chickens is probiotics. To the best of our knowledge, there is currently no study available on the use of phages and probiotics in combination as potential feed additives for broiler chickens. Therefore, this study demonstrated the effects of a phage cocktail, probiotics, and their combination on the growth performance and gut microbiota of broiler chickens. A total of 288 one-day-old male Cobb 500 broilers were randomly allotted to one of six treatments in a completely randomised design. The treatments were (i) C (basal diet (BD) only), (ii) 1ϕ (BD + 0.1% phage cocktail), (iii) 2ϕ (BD + 0.2% phage cocktail), (iv) P (BD + 0.1% probiotic), (v) 1ϕP (BD + 0.1% phage cocktail + 0.1% probiotic), and (vi) 2ϕP (BD + 0.2% phage cocktail + 0.1% probiotic). The 1ϕP treatment had significantly (p < 0.05) better BW (35 days), BWG (22-35 days, 1-35 days), and FCR (1-21 days, 22-35 days, 1-35 days) compared to C. Unique gut microbiota diversity was also found between the ϕP (1ϕP and 2ϕP) and non-ϕP groups (C, 1ϕ, 2ϕ, and P) in ilea, particularly in the 35-day-old chickens. Microorganisms associated with short-chain fatty acid (SCFA) producers were significantly (p < 0.05) more present in the ϕP group than in the non-ϕP group. The predicted genes related to carbohydrate and amino acid metabolism were significantly upregulated in ϕP groups compared to non-ϕP groups. These genes were involved in the digestion and absorption of nutrients, as well as the production of energy. Our findings showed that the 1ϕP treatment could be a potential alternative to AGPs for poultry, as growth performance was enhanced, and gut microbiota was positively modulated.

Screening and formulation of novel carriers for Xanthomonas bacteriophage to control bacterial leaf blight disease

Aims@#This study was aimed to evaluate the potential of several carriers to formulate the phages and retain their activity under various pH and temperature conditions.@*Methodology and results@#The skim milk, rice flour, corn flour and CalnuXan (calcium and magnesium) as carriers to formulate the isolated phage to maintain its activity under extreme pH and temperature conditions. Two phages formulated with carriers retained their viability at pH 5, pH 7 and pH 9 compared to that of the unformulated phages. Besides, the formulated phages also retained a high titre compared to the unformulated phages when they were exposed to 37 °C and 45 °C. Based on the in vitro study of the formulation, it was applied in the glass house. The plant height, leaf chlorophyll and disease scoring were recorded and analyzed. In the glass house, the rice plant treated with formulated phages showed higher plant height and chlorophyll content than those treated with unformulated or untreated phages. Nonetheless, both formulated and unformulated protected the rice plant, which showed lower disease severity than the untreated group.@*Conclusion, significance and impact of study@#Phage therapy has been used for treating plant diseases caused by pathogenic bacteria. Despite their effectiveness in killing the pathogen in vitro, the results were not reproducible in the field. Bacteriophages (phages) are sensitive to environmental factors and infection efficiency was dropped when exposed to harmful environments. However, this study successfully formulated two novels Xanthomonas phages, as biocontrol agents against bacterial leaf blight (BLB) disease in rice.

Antibacterial activity of Sireh (Piper betle L.) leaf extracts for controlling bacterial leaf blight diseases in rice plant

Aims@#This study aimed to determine the antibacterial activity of Piper betle L. leaf extract against Xanthomonas oryzae pv. oryzae that causes bacterial leaf blight in rice plant.@*Methodology and results@#The antibacterial activity of the P. betle leaf extract (100, 50, 25 and 12.25 mg/mL) with four different solvents (methanol, ethyl acetate, hexane and acetone) was evaluated using a disc diffusion assay, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. The inhibition zone of methanolic extract appeared to have the maximum diameter compared to those of other extracts, which is 32.67 mm at a concentration of 100 mg/mL, followed by 30.33 mm, 22.00 mm and 20.30 mm for the concentrations of 50 mg/mL, 25 mg/mL and 12.5 mg/mL, respectively. The MIC and MBC values of the methanolic extract were 0.625 mg/mL suggesting that the extract has a bactericidal effect on X. oryzae pv. oryzae (Xoo). The time-kill curve studies revealed that the 1× MIC (0.625 mg/mL) concentration of methanolic extract had a time and concentration-dependent killing effect on Xoo. Gas chromatography-mass spectrometry (GC-MS) analysis of methanol extract revealed the presence of eugenol acetate (29.53%), 4-allyl-1,2-diacetoxybenzene (29.51%) and 2,3-dimethyl benzoic acid (22.82%) as major compounds.@*Conclusion, significance and impact of study@#The methanolic leaf extract of P. betle was proven to have an effective inhibitory effect on Xoo and may have the potential to be used as an alternative management strategy for controlling rice diseases. In the future study, the methanolic leaf extract of P. betle is one of the recommendations to be applied in glasshouse and field trials.

Isolation, screening and characterization of bacteria associated with cocoa tree roots for different plant growth promotion (PGP) activities

Aims@#Plant growth promoting rhizobacteria (PGPR) is a group of bacteria that colonise plant roots and enhance plant growth by a diverse range of mechanisms. This study aims to determine the capabilities of PGPR isolated from cocoa tree roots and their efficiency in enhancing plant growth under greenhouse conditions.@*Methodology and results@#Eight samples of healthy cocoa tree roots were collected from different locations in Malaysia. Isolated bacteria were screened based on nitrogen fixation, phosphate and potassium solubilization, and catalase activity. The efficiency of purified PGPR was evaluated from pot experiments of cocoa seedlings under greenhouse conditions. Out of 122 isolates, 18 isolates showed several traits of nitrogen fixation, phosphorus and potassium solubilization and were further screened for other plant growth promoting (PGP) traits like catalase and production of indole acetic acid (IAA). Out of all the PGP trait tests, seven isolates showed the most prominent results for in vitro tests and were further tested in vivo for growth promotion of cocoa seedlings under greenhouse conditions. In the presence of bacterial isolates with 2.5 g of inorganic fertilizer, Leclercia adecarboxylata resulted in increases in plant height, leaf number, root length, stem fresh weight and total fresh and dry weight of cocoa seedlings by 15.68%, 17.14%, 9.48%, 5.67%, 11.84% and 25.12%, respectively.@*Conclusion, significance and impact of study@#Based on the result, L. adecarboxylata incorporated with selected carrier material improve cocoa seedling growth and biomass. This formulation also reduces the production cost of inorganic fertilizer and increase the application and development of biofertilizer.