Inefficient dietary nitrogen (N) conversion to microbial proteins, and the subsequent use by ruminants, is a major research focus across different fields. Excess bacterial ammonia (NH₃) produced due to degradation or hydrolyses of N containing compounds, such as urea, leads to an inefficiency in a host's ability to utilize nitrogen. Urea is a non-protein N containing compound used by ruminants as an ammonia source, obtained from feed and endogenous sources. It is hydrolyzed by ureases from rumen bacteria to produce NH₃ which is used for microbial protein synthesis. However, lack of information exists regarding urea hydrolysis in ruminal bacteria, and how urea gets to hydrolysis sites. Therefore, this review describes research on sites of urea hydrolysis, urea transport routes towards these sites, the role and structure of urea transporters in rumen epithelium and bacteria, the composition of ruminal ureolytic bacteria, mechanisms behind urea hydrolysis by bacterial ureases, and factors influencing urea hydrolysis. This review explores the current knowledge on the structure and physiological role of urea transport and ureolytic bacteria, for the regulation of urea hydrolysis and recycling in ruminants. Lastly, underlying mechanisms of urea transportation in rumen bacteria and their physiological importance are currently unknown, and therefore future research should be directed to this subject.

膳食氮 (N) 转化为微生物蛋白质的效率低下，以及反刍动物随后的利用，是不同领域的主要研究热点。由于含氮化合物（例如尿素）的降解或水解而产生过量的细菌氨（NH ₃），导致宿主利用氮的能力低下。尿素是一种不含蛋白氮的化合物，被反刍动物用作氨源，从饲料和内源中获得。它被来自瘤胃细菌的脲酶水解产生用于微生物蛋白质合成的NH _{3 。}然而，缺乏关于瘤胃细菌中尿素水解以及尿素如何到达水解位点的信息。因此，本文综述了尿素水解位点、尿素向这些位点的转运途径、尿素转运蛋白在瘤胃上皮和细菌中的作用和结构、瘤胃尿素分解细菌的组成、细菌脲酶水解尿素的机制以及影响因素的研究。尿素水解。本综述探讨了目前关于尿素运输和尿素分解细菌的结构和生理作用的知识，以调节反刍动物尿素水解和再循环。最后，瘤胃细菌中尿素运输的潜在机制及其生理重要性目前尚不清楚，因此未来的研究应针对这一主题。