However, microaerophiles metabolise energy aerobically, and obligate anaerobes metabolise energy anaerobically. Anaerobic gram-positive cocci are frequently isolated from anaerobically infected bones and joints. The HomeBiogas system generates biogas by anaerobically fermenting organic matter. Unlike bacteria, no known yeast species grow only anaerobically (obligate anaerobes). In addition to aerobic methylotrophy, methane can also be oxidized anaerobically. Fructose may be anaerobically fermented by yeast or bacteria. The settled solids are anaerobically digested, reducing the volume of solids. During brumation, "T. s. elegans" can survive anaerobically for weeks, producing ATP from glycolysis. "F. hepatica" has no respiratory organs&colon; the adult flukes respire anaerobically (without oxygen). Some strains cannot grow anaerobically on sucrose and trehalose. The water is treated anaerobically and the biogas is used for energy production. Corn, alfalfa, wheat, oats, and sorghum crops are often anaerobically fermented to create silage. The muscle cells, lacking in oxygen, begin to function anaerobically to produce the needed ATP. In the third stage, sulfophilic bacteria anaerobically break down the lipids embedded in the bones. Thread-locking fluid is a thixotropic adhesive that cures anaerobically.