| The Broussonetia papyrifera is a valuable source of woody fodder with high nutritional value.However,the utilization efficiency is low due to the high fiber content when the whole-plant is used.This study aimed to promote the use of Broussonetia papyrifera by screening lactic acid bacteria with ferulic acid esterase-producing function from various bacterial sources.These bacteria were then used as silage additives either alone or in combination with different enzymes(cellulase and xylanase)to improve the quality of Broussonetia papyrifera silage.The effects of the screened lactic acid bacteria and enzyme additives on the fermentation and fiber components of tree silage were evaluated by measuring and analyzing dynamic indicators such as fermentation characteristics,fiber components and microbial community structure of tree silage,so as to screen the additives that can improve the fiber degradation rate and silage quality of tree silage.The main results were as follows:(1)In this experiment,six strains of lactic acid bacteria with ferulic acid esterase-producing function were screened from hundreds of strains of lactic acid bacteria.16 Sr DNA sequence homology comparison showed that all six strains were Lactobacillus plantarum.The physiological and biochemical results showed that the optimum growth temperature of all bacteria was between 30-37°C.The acid production rate,growth rate and temperature tolerance of Lactobacillus plantarum L1(L.plantarum RO395),which was screened from rumen fluid,were stronger than those of L2(L.plantarum RO392),L3(L.plantarum LY310),L4(L.plantarum MX211),L5(L.plantarum HX211)and L6(L.plantarum LX261).Secondly,it was observed from the Oxford cup medium that L1 produced the largest clear circle,L5 the smaller,L2 the smallest and the rest the medium.Considering all,L1 was selected as the additive for the subsequent silage trials.(2)In this experiment,lactic acid bacteria L1,xylanase and cellulase were selected as silage additives for Broussonetia papyrifera silage fermentation.The results showed that the use of L1 and enzyme additives had a good effect on the silage fermentation of Broussonetia papyrifera.First,the addition of L1 effectively increased lactic acid(LA)content(P<0.05)and reduced p H in silage(LA content was 73.44 g/kg DM and p H decreased to 4.42 at 60 days of silage in the LP+CE+XY treatment group),and also inhibited butyric acid(BA)production(P<0.05).In particular,the combination of L1 and two enzyme preparations(cellulase and xylanase)was more effective in improving silage fermentation characteristics and quality,not only by reducing p H(P<0.05)and dry matter loss(P<0.05),but also by greatly improving the degradation of lignocellulose,with lower neutral detergent fiber content(427.00 g/kg DM)and acid detergent fiber content(216.77 g/kg DM)detected in the LP+CE+XY treatment at 30 days of silage,it was a decrease of 44.61 and 24.93 g/kg DM(P<0.05)compared to the neutral detergent fiber(471.61 g/kg DM)and acidic detergent fiber content(241.70 g/kg DM)of the CK treatment,respectivel.In addition,both enzyme preparation and LP significantly improved the bacterial diversity and community structure of the silage process,and the combination of L1 with enzyme preparation resulted in a more effective increase in the relative abundance of beneficial bacteria(e.g.Firmicutes,Lactiplantibacillus)compared to the use of enzyme preparation alone.Overall,the combined use of L1 bacteria with two enzyme preparations achieved better improvement in the silage fermentation of the Broussonetia papyrifera.In summary,in the present study,erulic acid esterase-producing lactic acid bacteria with excellent physiological properties were screened from the perspective of fiber degradation.It was also found that this bacterium had a significant synergistic effect with cellulase and xylanase combination during silage fermentation,which could effectively degrade the fiber components of silage and improve the fermentation,providing a new solution for the efficient fodder utilization of Broussonetia papyrifera. |
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