PENGARUH REKAYASA SPEKTRUM PENCAHAYAAN LED TERHADAP PERTUMBUHAN CHLORELLA VULGARIS PADA PLANT FACTORY

Abstract

Mikroalga merupakan biomassa fotosintetik yang memiliki potensi besar untuk produksi pangan, bioenergi, farmasi, dan oleokimia. Budidaya mikroalga secara konvensional umumnya dilakukan dalam sistem terbuka seperti open raceway ponds, memiliki keterbatasan termasuk fluktuasi suhu musiman, kualitas udara, dan kontaminasi oleh spesies yang tidak diinginkan. Penelitian ini mengusulkan model budidaya terkontrol untuk mikroalga menggunakan sistem plant factory yang dilengkapi dengan pencahayaan LED buatan. C. vulgaris dipilih dalam penelitian ini karena memiliki kandungan lipid dan protein yang tinggi serta laju pertumbuhan yang cepat, sehingga berpotensi menjadi sumber bioenergi yang menjanjikan. Tahapan penelitian meliputi budidaya mikroalga, pengukuran berat sel kering, dan evaluasi pertumbuhan mikroalga. Eksperimen dilakukan menggunakan dua perlakuan pencahayaan yaitu LED grow light merah-biru (daya lampu 20 W, PPFD 51 µmol m?² s?¹, dan intensitas cahaya 2.897 lux) serta LED putih (daya lampu 24 W, PPFD 96 µmol m?² s?¹, dan intensitas cahaya 4.845 lux) dengan fotoperiode 12:12 jam (terang:gelap) dan jarak pencahayaan ± 30 cm. Hasil penelitian menunjukkan bahwa pertumbuhan mikroalga tertinggi dicapai di bawah pencahayaan LED kombinasi merah-biru dibandingkan putih. Kultur yang diberi pencahayaan LED merah-biru mengalami perubahan warna menjadi kuning lebih cepat dibandingkan dengan kultur yang diberi pencahayaan LED putih, yang disebabkan oleh penurunan laju fotosintesis. Kurva pertumbuhan menunjukkan tiga fase yang berbeda: fase lag, eksponensial, dan stasioner, dengan koefisien determinasi (R²) sebesar 0,96, menunjukkan kecocokan model yang kuat. Suhu di dalam plant factory diatur pada 24°C dan dikendalikan secara otomatis, menghasilkan rata rata suhu harian ± 19°C, sementara pH kultur berkisar antara 7,7 hingga 8,6. Kepadatan sel dan berat sel kering meningkat seiring waktu selama fase pertumbuhan, tetapi menurun selama fase stasioner, menyebabkan penurunan biomassa total. Selain itu, konsentrasi nitrat dalam medium kultur menurun sepanjang periode budidaya, mencerminkan penyerapan nutrisi oleh mikroalga. Temuan ini menunjukkan bahwa pencahayaan dan kondisi lingkungan yang terkontrol secara signifikan mempengaruhi akumulasi biomassa dan status fisiologis C. vulgaris.

Microalgae are photosynthetic biomass with significant potential for food, bioenergy, pharmaceutical, and oleochemical production. Conventional microalgae cultivation is commonly conducted in open systems such as open raceway ponds, which face limitations including seasonal temperature fluctuations, air quality, and contamination by undesirable species. This study proposed a controlled cultivation model for microalgae using a plant factory system equipped with artificial LED lighting. C. vulgaris was selected for this study because it has a high lipid and protein content and a rapid growth rate, making it a promising source of bioenergy. The research consisted of microalgae cultivation, dry cell weight measurement, and evaluation of microalgal growth. The experiment was conducted using two lighting treatments: red-blue LED grow lights (20 W lamp power, PPFD of 51 µmol m?² s?¹, and a light intensity of 2,897 lux) and white LED lights (24 W lamp power, PPFD of 96 µmol m?² s?¹, and a light intensity of 4,845 lux). The experiment was performed under a 12:12 h light-dark photoperiod with a lighting distance of approximately 30 cm. The results showed that the highest microalgal growth was achieved under red-blue LED lighting compared with white LED lighting. The cultures exposed to red-blue LED lighting turned yellow more rapidly than those exposed to white LED lighting, which was caused by a reduction in the photosynthetic rate. The growth curve exhibited three distinct phases: lag, exponential, and stationary, with a coefficient of determination (R2) of 0.96, indicating a strong model fit. The temperature inside the plant factory was set at 24°C and automatically controlled, resulting in an average daily temperature of approximately 19°C, while culture pH ranges from 7.7 to 8.6. Cell density and dry cell weight increased over time during the growth phase but decreased during the stationary phase, resulting in a reduction in total biomass. Additionally, nitrate concentrations in the culture medium decreased throughout the cultivation period, reflecting nutrient uptake by the microalgae. These findings indicated that controlled lighting and environmental conditions significantly influenced biomass accumulation and the physiological status of C. vulgaris.