Identification and characterization of lactic acid bacteria associated with tropical grass silage produced in Okinawa

In Okinawa, rate of increase in gross agricultural production during 2011‒2016 was the highest in Japan and sales of calves ranked fourth throughout Japan. Raising cattle by feeding high quality silage is beneficial both nutritionally and economically. However, little is known about lactic acid bacteria (LAB) present in silages made from tropical grass in Okinawa. To improve understanding of fermentation processes in silages, the LAB present in a range of silages (Digitaria eriantha, Megathyrsus maximus, Chloris gayana, Urochloa mutica, Sorghum sp. and Zea mays) were identified. All isolates were Gram-positive and mainly catalase-negative bacteria. According to morphological and biochemical characters, 37 isolates were divided into 16 groups and on the basis of 16S rDNA sequence analysis, 7 were identified as Lactobacillus plantarum, 3 as L. paraplantarum, 1 as L. brevis, 1 as L. acidipiscis, 3 as L. casei, 1 as L. fermentum, 9 as Weissella paramesenteroides, 1 as W. kimchii, 5 as Lactococcus lactis subsp. lactis, 2 as Lactococcus garvieae and 4 as Pediococcus pentosaceus. Some of this wide variety of LAB in Okinawan silage could be beneficial for improving quality of silages and further studies are planned to determine benefits of inoculating forage with particular strains at ensiling.