To increase industrial applicability of Astragalus membranaceus (AM) as immunostimulating materials, hot-water extract (AME) was prepared from AM and fermented with Kimchi-lactic acid bacteria (Lactobacillus sakei & Leuconostoc mesenteroides) to prepare fermented AM-postbiotics (FAME). Although FAME prepared from AM-postbiotics did not show a significant enhancement in macrophage stimulating activity compared to non-fermented AME, crude polysaccharide (FAME-CP) fractionated by EtOH precipitation from FAME showed significantly higher macrophage stimulating activity than AME-CP. Compared to AME-CP, FAME-CP showed dramatic changes in component sugar and molecular weight distribution. FAME-CP was a polysaccharide with a major molecular weight distribution of 113.4 kDa containing Man (44.2%), Glc (19.3%), Gal (10.2%), GalA (10.2%), and Ara (7.4%) as sugar components. FAME-CP with enhanced macrophage stimulatory activity not only increased expression levels of mRNA genes encoding macrophage-activated factors (iNOS, TNF-α, MCP-1, IL-6, and COX-2), but also led the nuclear translocation of activated p65 and c-Jun. In conclusion, crude polysaccharide from AM-postbiotics fermented with lactic acid bacteria could increase industrial applicability as a functional material with enhanced immunostimulating activity than AME-CP.

To investigate the anti-inflammatory activity of submerged culture using Cordyceps militaris mycelium, culture-including mycelia was extracted and lyophilized into postbiotics (hot-water extract; CM-HW). HW was fractionated into crude polysaccharide (CM-CP) by ethanol precipitation, and CM-CP was further dialyzed into CM-DCP by dialysis with running water using 12~14 kDa dialysis tube. When the cytotoxicity of subfractions against cells was assessed, no subfraction had a cytotoxic impact that was substantially different from the control groups. In an inflammatory model using LPS-stimulated RAW 264.7 cells, CM-DCP significantly decreased IL-6 and MCP-1 production levels compared to the LPS-control group. CM-DCP also inhibited IL-6 and IL-8 secretion in HaCaT keratinocytes stimulated with TNF-α and IFN-γ. In the meanwhile, the neutral sugar content and mannose ratio of anti-inflammatory CM-DCP were higher than the other fractions, and CM-DCP contained β-1,3/1,6-glucan of 216.1 mg/g. High pressure size exclusion chromatography revealed that CM-DCP contained molecules with a molecular weight range of 5.6 to 144.0 kDa. In conclusion, postbiotics of C. militaris mycelium significantly promoted anti-inflammatory activity, suggesting that neutral polysaccharides including Glc and Man contribute to the anti-inflammation in RAW 264.7 or HaCaT cells.

After liquid culture of Phellinus baumii (P. baumii) mycelium (LPBM) was prepared, LPBM was fractionated into A∼E fraction (A; hot-water extract of liquid culture including mycelia, B; crude polysaccharide of A, C; hot-water extract of mycelia, D; crude polysaccharide of C, and E; crude polysaccharide of culture broth) to evaluate for possibility as functional materials with immunostimulatory activity. In macrophage stimulatory activity, E fraction as postbiotics significantly increased secretion of NO and IL-12 from RAW 264.7 cells. Next, when the splenocytes of C3H/HeN mice were primary cultured, E fraction showed significantly mitogenic activity with enhancing mitogen-related cytokines (IFN-γ and TNF-α) production from splenocyte. E fraction also potently stimulated GM-CSF production from Peyer’s patch cells as well as Peyer’s patch-mediated bone marrow cell proliferation. In addition, the immunostimularoy E fraction contained neutral sugar (73.8%), uronic acid (10.6%), protein (7.8%), and polyphenol (7.5%), and mainly consisted of glucose (39.1%), galactose (21.7%), mannose (11.1%), galacturonic acid (9.9%), and arabinose (8.9%) as component sugars. In conclusion, it was demonstrated that postbiotics including exopolysaccharide fractionated from liquid culture of the P. baumii mycelium could enhanced immunostimulatory activity.

포스트바이오틱스(postbiotics)는 프로바이오틱스(probiotics)가 발효과정 중 생산하는 유용한 대사산물과 미생물의 구성성분을 포 함하는 개념이다. 포스트바이오틱스는 기존 프로바이오틱스 소재가 갖는 안전성(safety), 기능성(function), 안정성(stability)의 한계를 극복할 수 있는 새로운 대안 소재로 주목받고 있다. 사균화 처리과정으로, 특정 대사물질의 복합물 형태로 제조되고 있기에 기존 생균제보다 가공, 포장, 유통, 섭취가 용이하다. 면역력이 낮은 환자나 건강 취약 계층의 소비자들도 안전하게 섭취할 수 있는 것도 장점이다. 뿐만 아니라, 체내에서 면역 조절, 감염 방지, 지질 및 콜레스테롤 대사, 항산화 기능을 보이고 있어, 앞으로 건강기능 식품 우수 소재로 활용될 가능성은 더 커질 것이다. 다만, 대부분의 연구들이 아직은 세포실험과 동물시험인 단계이기에 실제 인체적용 시험을 마친 소재들은 적은 편이다. 향후 꾸준한 연구성과를 바탕으로 다양한 기능을 가진 포스트바이오틱스 소재와 제품들이 개발된다면 건강기능식품 산업에 새로운 성장동력이 될 것으로 예상 된다.