Use of some of tannin-producing bacteria to reduce tannins and improve the nutritional value of Eucalyptus (Eucalyptus camaldulensis) leaves

Introduction: Eucalyptus leaves contain tannins and flavonoids (Asghari and Mazaheriani 2010). Tannins have beneficial and harmful effects depending on their concentration, animal physiological condition and diet composition (Dubai et al. 2011). By increasing the amount of tannins, the digestibility of proteins decreases and prevents the digestion of lignocellulosic materials that are dependent on extracellular enzymes (Babadi et al. 2018). In addition to the anti-nutritional effects of tannins at high concentrations, the positive effects of dense tannins at optimal concentrations include improved live weight gain, increased milk production, reduced NH3 and methane production in the rumen (Lim and Mortijaya 2007). Using methods that can reduce the amount of tannins, make tannins plants used more and more effectively in animal nutrition (Huang et al. 2018). In addition to chemical methods and other methods for de-tannins, there are also biological methods (Chaji et al. 2020; Mohammadabadi et al. 2020). The enzyme tanase, which leads to the breakdown of tannins, has wide applications in the food and chemical industries. In addition, tanase is used in the production of animal feed (Chavez-Gonzalez et al. 2012). Bacterial tanase can effectively break down and hydrolyze natural tannins and tannic acid (Kumar et al. 2015). Bacterial tanase can effectively break down and hydrolyze natural tannins and tannic acid (Kumar et al. 2015). Klebsiella pneumoniae and Acinetobacter, as tannin degraders isolated from deer rumen, improved the fermentation parameters of eucalyptus leaves, so the use of these isolates will be useful to improve the nutritional value of tannin-containing plants (Mohammadabadi et al. 2021). Japanese rats with the bacterium Lactobacillus, which produces tannins; Was able to adapt to tannin-rich foods (Sasaki et al. 2005). Therefore, in tropical and subtropical regions, the processing of tannin-rich trees with tanase is very important in animal nutrition systems (Mohammadabadi et al. 2020).
materials and methods: The tannin-degrading bacteria used in the present experiment were isolated from the rumen of deer and goat Najdi, and their ability to produce tanase and de-tannins them has already been investigated in experiments (Chaji et al. 2020; Mohammadabadi et al. 2020; Mohammadabadi et al. 2021). The tannin degrading bacteria used in the present experiment included Klebsiella pneumoniae and Acinetobacter isolated from deer rumen, Lactobacillus fermentum isolated from Najdi goat rumen and commercial Lactobacillus fermentum. For processing, eucalyptus leaves, after turning them into 3-4 cm pieces, were tested in 10 liters of distilled water containing 1 liter of Nutrient Broth solution containing bacteria (107 cfu / ml) and to anaerobize the environment, immediately were transferred in10 kg plastic bags, and were closed and kept at 37 ° C for 10 days. After leaving the bags, they were dried, ground and mixed with rations, were given to lambs (Mohammadabadi et al. 2021). Experimental treatments include 1- Eucalyptus leaves or diets containing it without processing (control), treatment 2-5- Eucalyptus leaves or diets containing it that were treated with any of the four tannin-degrading bacteria. Then, the nutritional value of eucalyptus leaves alone or in combination with diet of fattening lamb, was studied by two-step digestion and gas production experiments.
Results and discussion: The effect of experimental treatments on gas production potential, gas production rate, truly degraded organic matter, and production of microbial biomass of eucalyptus leaves and diets containing it was significant (P <0.05). The gas production potential of all experimental treatments was higher than the control (P <0.05). The digestibility of DM, NDF and ADF of eucalyptus leaves, and diets containing it in all treatments was significantly higher than the control treatment (P <0.05). The effect of experimental treatments on NH3 concentration, pH, and protozoan population of ruminal fluid of eucalyptus leaves and diets containing leaves was significant (P <0.05). Increased gas production in the treated treatments and the reason for significant improvement or numerical of gas production parameters can be attributed to the role of tanase-producing bacteria used in the decomposition of eucalyptus leaf tannin (Yarahmadi et al. 2017). In fact, tannins reduce ruminal fermentation by inhibiting the activity of microorganisms or microbial enzymes (Goel and McCarthy 2012). Increase though numerically of actually decomposed or digested material, microbial efficiency and PF in some treatments indicate the effect of tanase-producing bacteria in the present experiment (Gatacho et al. 2008). Tannins inhibit the digestion of fibers and proteins, so reducing the level of tannins by isolates, increases the activity of proteolytic enzymes and improves the digestibility of feed by releasing nutrients from the tannin binding (Goel et al. 2005). Tannins also reduce the concentration of NH3 by binding to proteins and reducing the rate of protein degradability (Ben Salem et al. 2005). The decrease in protozoan population in the control treatment and its increase during treatment with tanase-causing bacteria is probably due to the polyphenolic structure of these foods (Goel et al. 2005).
Conclusion: The results of this experiment showed that the use of tanase-producing bacteria degraded leaf tannins and improved its quality, so their use can be a good way to reduce tannins and improve the nutritional value of eucalyptus leaves for livestock.

ntroduction: Eucalyptus leaves contain tannins and flavonoids (Asghari and Mazaheriani 2010). Tannins have beneficial and harmful effects depending on their concentration, animal physiological condition and diet composition (Dubai et al. 2011). By increasing the amount of tannins, the digestibility of proteins decreases and prevents the digestion of lignocellulosic materials that are dependent on extracellular enzymes (Babadi et al. 2018). In addition to the anti-nutritional effects of tannins at high concentrations, the positive effects of dense tannins at optimal concentrations include improved live weight gain, increased milk production,