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Basic Facts  - **Scientific name**: Tremella aurantialba   - **Other names**: Brain Fungus, Brain-shaped Tremella, Orange Tremella, Yellow Fungus   - **Classification**: Tremellales, Otodendraceae, Genus Tremella   - **Ecological distribution**: Primarily Southwest and East China   - **Morphological characteristics**:    - Brain-shaped or irregularly lobed fruiting body (8–15 cm diameter), single or clustered.    - Surface: Smooth initially, developing brain-like lobes with maturity; firm, fleshy, turning golden/orange-yellow under good ventilation and moderate light.    - Late maturity: Soft internal tissue; white powdery basidiospores in lobed grooves (pale yellow when aggregated).    - Cross-section: Golden edges (golden fungus mycelium); white center (hairs of golden fungus and tough leathery fungus *Stereum hirsutum*).    - Variations: Color and size depend on cultivation methods.  

1. Cultivation History   - 1815–1822: Mycologist Eles Fries first studied golden fungus, establishing the genus *Naematelia*.   - 1983: Huang Nianlai et al. isolated parent species and domesticated cultivation, but fruiting body yield was unstable.   - 1982–1996: Liu Zhengnan, Zheng Shufang, etc., achieved breakthroughs in log and substitute cultivation (proven suitable for wide application).   - Recent years: Yunnan Junshijie Biotechnology developed factory-scale cultivation, expanding cultivation north of the Yangtze River.   - Current challenges: Short cultivation history, low public awareness, limited cooking methods, ordinary taste → low market acceptance.   - Market status: Fresh golden ear has higher ex-factory price than white ear, but few pre-processed products and inferior taste hinder promotion.  

2. Biological Characteristics  

- **Nutrition**:    - Pure golden fungus mycelium weakly decomposes lignocellulose; relies on companion fungus *Stereum hirsutum* (tough leathery fungus) to break down macromolecules into absorbable nutrients.    - *Stereum hirsutum* can complete its life cycle independently; golden fungus cannot (mixed mycelium type).    - Similar to white ear (*Tremella fuciformis*), which also needs a companion fungus (ascomycete); both have nearly identical nutritional profiles.    - Reproduction: Budding produces yeast-like conidia; germinate into hyphae in slag extract medium (white ear’s germination is hindered by colloids).  - **Temperature**:    - Mesophilic; optimal for *Stereum hirsutum* hyphae: 22–25°C.    - Basidiospore budding phase: 18–22°C.    - Low temperatures control *Stereum hirsutum* growth and stimulate golden fungus fruiting body development.    - (Note: Golden ear, white ear, and black fungus share the same optimal fruiting body temperature: 18–22°C.)

 - **Light**:    - Avoid light during cultivation (mimics natural ecology); e.g., log-inoculated mycelium grows under bark, substitute sticks incubate in darkness until mature.    - Strong diffuse light (300–500 lux) stimulates formation of pale yellow/orange fruiting bodies.

 - **Water**:    - Substitute medium moisture: 60%–62%.    - Fruiting body growth humidity: 90%–92% (low humidity slows growth; high humidity risks rot).    - Humidity differences promote growth; ground irrigation + internal circulation fans increase humidity.  

- **Air**:    - Oxygen-intensive; requires constant fresh filtered air.    - Poor ventilation at high temperatures impairs ear bud development.

 - **pH**:    - Thrives in neutral to slightly acidic environments (optimal substrate pH: 6.0–6.5).    - Spores and *Stereum hirsutum* tolerate a wide pH range; adjust to 6.5–7 with gypsum or potassium dihydrogen phosphate in production.  

3. Production Model  - **Cultivation method**: Dominated by substitute materials (log cultivation is obsolete due to long cycles and low conversion rates).   - **Regional timing**: Spring cultivation in northern China; spring and autumn in southern China.

 - **Key note on strains**:    - Golden fungus hyphae and *Stereum hirsutum* hyphae have a symbiotic (one-sided) nutrient transfer relationship (similar to white ear and its companion fungus *Xylaria*).    - Pure golden fungus hyphae grow slowly and cannot form fruiting bodies alone; depend on *Stereum hirsutum* for nutrients.    - Unlike wood ear (single hyphae type), golden ear and white ear have mixed hyphae types.